APPENDIX: THE WORLD OF WEATHER

<12.1 Initial Weather Conditions>

ADQ: Why isn't there any weather in
the AD&D game system? My Druid
never uses the powerful Call Lightning
unless the DM feels like having a
storm!
ADA: My old friend (and RPGA
Member) Dave Axler asked the same
question, and did something something about it.
Look in Dragon #68.
(Polyhedron #12)


Introduction
Basic Assumptions
Climatic Regions
Rain, Sleet, or Snow
Collecting Precipitation
Extraordinary Precipitation
Special Weather Definitions
Optional Rules
-
WSG
-
-
-
-
-
Heng (god of weather)
Hotoru (god of weather)
Marduk (god of weather)
Lei Kung (god of foul weather)
Raiden (god of weather)
Frigga (goddess of weather)
Aerdrie Faenya
(goddess of weather)
-
Sheela Peryroyl
(goddess of weather)
Velnius (god of weather)

Intro
A system for determining the weather at any time && place in
the campaign world is a necessary part of a set of rules that defines
and describes that world. Yet weather, by it's very nature, is
anything but systematic. Modern-day meteorologists, armed with
all the equipment && knowledge that man has devised && accumulated,
still can't always predict with certainty what the
weather will be from one day to the next -- so how can a game designer
hope to accomplish what they cannot?

The resolution of this paradox lies in the judicious USE of one of
the designer's most valuable tactics: simplicity. The tables &&
text on these pages may not look simple at first glance, but they
are simple indeed compared to what would have been needed to
account for all the combinations of terrain, climate, elevation, and
location that exist on Earth. The system given here will enable a
DM to predetermine the important weather conditions
that will prevail on any day (and for days || weeks in advance,
if desired) at any loc. in the world.

The system has been constructed so that parts of it, such as
the sections on wind chill && humidity, can be disregarded if the
DM prefers even more simplicity than the designer built
in. The basic structure requires the DM to consult only two
tables, and make a single dice roll, to determine the temperature,
wind speed and direction, and precipitation (if any) for any day
exc. one on which a special weather phenomenon takes place.

Note that this system describes how to determine weather conditions,
but does not explicitly describe the effects, in game terms,
that the weather will have upon characters, creatures, or
other elements present in the environment. Information on the effects
of weather is presented in the first section of this book, for
both players and DMs. The difference, of course, is that the
DM will know exactly what the weather conditions
are or will be, while PCs (and their players) in most
cases only will be able to make general inferences and observations
based on the info the DM imparts to them -- and
they, unlike the DM, usu. will not know what the weather has in
store for them during the hours and days to come.

Basic Assumptions
A day is about 24 hours in duration;
a year is 365 days in length, or thereabouts.
(Many <DMs> prefer to develop their own calendars,
and a good number of those conveniently divide the year into twelve identical months of 30 days each,
making each year 360 days long.)
Each year is divided into four seasons, and each <4>
of the seasons is further divided into three months. <3>
The planet rotates in a counterclockwise direction, as viewed
from a point above the north pole.
Temperatures are expressed in degrees
Farenheit, elevation in feet above sea level, and
wind velocity in mph. Wind direction is given as the
direction the wind is
coming from; a north wind blows from N to S, not the
other way around.

The planet contains five climatic regions, each described <5>
in detail below. The system considers seven basic types of terrain, <7>
which are defined in the first part of this book. Although these
terrain/climate designations do not directly correspond with the
terrain && climate categories given in the encounter tables in the
DMG and MM2, translation is not
difficult.

If you use the DMG terrain categories, consider scrub
and rough areas to be id. (for weather determination) as
plain || forest, depending on which of those latter areas the
terrain most closely resembles. Swamp areas, whenever this
category is not specifically mentioned (such as on the Temperature
Variation table), are considered as either plain, forest, or seacoast,
depending on which of those three latter types most obviously <3>
applies. A swamp devoid of vegetation is a plain; a
swamp containing trees or other large vegetation is a forest; and
a swamp adjacent to the ocean is seacoast.)

MM2
considers only three climatic categories: cold, temperate, and <3>
tropical. To mesh that system with this one, simply divide the sub-arctic
&& sub-tropical areas in half, so that monsters encountered
in a cold climate will be found in the arctic and in part of
the subarctic adjacent thereto. Those encountered in a tropical
climate are found in the tropics and in the adjacent half of the
subtropical AREA. And, monsters that occur in a temperate climate
will be found in any AREA between the two extremes, encompassing <2>
the temperate AREA (as described herein) + the adjacent
half of the sub-arctic and the adjacent half of the sub-tropical AREA.

Climatic Regions

Arctic climate prevails in latitudes from 90º (the north || south pole) to 66º (the approximate location of the Arctic Circle).

In this text, "arctic" refers to the polar region in both the
northern && southern hemispheres (and id. gen. rule
applies to sub-arctic, temperate, and sub-tropical regions, described
below). The arctic is, in a word, c-c-cold. The temperature
sometimes rises to tolerable levels in the height of summer, but
for most of the year the arctic region is so frigid that it is essentially
uninhabitable, exc. by characters who are outfitted for
survival in the deep freese (and, of course, by creatures && monsters
that are adapted to -- and might even thrive in -- this kind of
climate).

The winds in this AREA gen. blow from east to west and seldom reach greater than moderate velocity (15-20 mph) exc. during storms.
However, even a light breeze can make a
drastic difference in effective temperature when it is bitterly cold
to begin with; see the section below on wind chill and its effects.

In every other climatic AREA, the amount of precipitation a certain
locale receives depends on the time of year, the type of terrain
in the locale, or both. But in the arctic, time of year makes no
appreciable difference and terrain distinctions are for the most
part irrelevant since everything is covered with ice. (On the Temperature Variation table
below, the entries are identical for arctic
hills && arctic mountains, and also for arctic desert && arctic
plains; temperatures for an arctic forest AREA are not given, since
vegetation of the normal sort cannot survive in this climate.) Precipitation in
the arctic is usu. very light if it exists at all.

A phenomenon unqiue to the arctic is the "midnight sun,"
which occurs during spring && summer. Because the Earth rotates
around an axis that is tilted with respect to The Sun, there is a
period of time each year when the arctic region is in continual
daylight; at any time during the planet's rotation, the arctic is
tilted toward The Sun. The converse of this is the long arctic winter
night (the "noon moon"?), when for an =equal= length of time in autumn &&
winter the region is tilted away from The Sun and is in
constant twilight. This difference in the amount of daylight each
day occurs at all latitudes, of course (exc. right at the equator,
where day && night are of virtually identical length), but only in
the arctic are the extremes of all-night days and all-day nights realized.
(See the Hours of Daylight Table in the Optional Rules
section for more info.)

Subarctic climate is typical of areas from 65° latitude to 51°.

(In the northern hemisphere, the southern boundary
of this AREA roughly describes the border between the US
&& Canada.)
Winters are long and cold,
but there is also a season that can be legitimately called summer;
daytime temperatures during the warm part of the year may reach or exceed 80°.
Winds are somewhat more active here than in
the arctic. In the winter, winds usu. blow from the arctic or on a
westerly angle from the arctic (NW in the northern hemisphere,
SW in the southern hemisphere), which in the summer
a prevailing westerly or tropical W wind (SW in the
northern hemisphere, NW in the southern hemisphere) is
more often the case.

Temperate climate extends from 50° latitude to 31° (in the northern hemisphere, the l. that roughly describes the border between the United States and Mexico).
It is the Earth's AREA of climatic compromise, and paradoxically also
the AREA where the greatest xtremes of temperature are recorded.
As anyone who lives in the the American Midwest can attest
to, a temperate winter can be a real bone-chiller -- and on the
hottest days of a temperate summer, going into a steam bath to
cool off can seem like a good . WInds can blow from the
N, S, or W, but almost never from the E (exc.
along eastern seacoasts and in localized areas, such as the
breeze that sometimes blows from Lake Michigan across the
Wisconsin && Illinois shoreline; see the discussion of Local Winds in
the Optional Rules section). Wind velocity in the temperate
zone is as variable as the temperature.

Subtropical climate predominates from 30 degrees latitude to 16 degrees (a l. running along the southern edge of Mexico).
This AREA, like the temperate zone, is one of climatic extremes,
but here they are more closely related to terrain. The sub-tropical
AREA of Earth's northern hemisphere includes the vast deserts of
Africa and Arabia, where rain hardly ever falls, and also the forests &&
jungles of India and SE Asia, where during the
summer it rains almost constantly. The warm months can be very
warm -- as hot as the tropics -- and in tthe cooler months, night-time
low temperatures can actually be rather brisk. Winds in the
AREA are highly variable in velocity, and they gen. blow from
the E or from the E and toward the equator -- the "trade
winds" that explorers from Europe took advantage of on their
journeys to the New World.

Tropical climate, in the area from 15 degrees latitude to 0 degrees (the equator) is as consistently hot as the arctic is consistently cold.
The temperature almost never drops below 70 degrees,
exc. during the winter months at high elevation when
a "cold snap" of 65 || 60 degrees might occur. The summer is
blisteringly hot, esp. in flat areas (desert && plains)at low
elevation, and even being along the seacoast offers little relief.
Winds are gen. docile (exc. during storms, of course), and
they most often blow in id. direction as the sub-tropical
trade winds.

Table A1: TEMPERATURE VARIATION
- - Winter 12 1 2 Spring 3 4 5 Summer 6 7 8 Autumn 9 10 11
Arctic D ABG ABH ACH AEH CGK FJL JKN JKM FHK DGJ ADH ABH
- F - - - - - - - - - - - -
- H ABE ABD ACF ADG BEI CFI DGL DGK CFJ CEH BEH ACE
- M ABE ABD ACF ADG BEI CFI DGL DGK CFJ CEH BEH ACE
- P ABG ABH ACH AEH CGK FJL JKN JKM FHK DGJ ADH ABH
- Se ACH ABH ACH AEJ CGK FJN JKP JKN EIL CGJ AEI ACI
- - Winter 12 1 2 Spring 3 4 5 Summer 6 7 8 Autumn 9 10 11
Subarctic D ADI ADJ BEJ CGJ FKM JLN KMQ JMQ GKQ FHM CEL ACI
- F AEJ AEI BGK DJL HKN JLP KMR JMR IKP EJL BHK AFJ
- H ADI ADI BFJ CGJ FKN JLN JMP IMP GKM DJL BGK ADJ
- M ACI ADI AFJ BHL EJM IKM JLN IMO GKM DJL BFK ADJ
- P ADI ADJ BEJ CGJ FKM JLN KMQ JMQ GKQ FHM CEL ACI
- Se BFK BGK CHK DJM HKN JLR KMR KMR JLP EKM CHL AFK
- Sw
- - Winter 12 1 2 Spring 3 4 5 Summer 6 7 8 Autumn 9 10 11
Temperate D KMS KMT LMT MNW MPX PPZ UYZ UYZ QWY NSX LRX KMR
- F CFL BFK EKP HLP KNU MPV MSX MSX LPV JNR FJL DJL
- H BIL CJM EKP ILR JOT JQX LTY LTY KQW JNT FKP CJM
- M AIL BIM CJN EKQ FLS KOV LQX KQW INU ELS CKR BJL
- P BHM CHN DKQ GLS KNU LPX MSY MSY KPW GLS EKQ CJM
- Se EJM FKN IKQ KLS KMT LOW MPX MPW LOW KLT GKP EKM
- Sw
- - Winter 12 1 2 Spring 3 4 5 Summer 6 7 8 Autumn 9 10 11
Subtropical D LPT LPU MSW NTX OTX RVY TXZ TXZ RUY PUY NSX MPW
- F LTU LTV MTV NTW NTX PUX PUX PUX OUW NUW MSV LSV
- H KNQ KOR LQU MSV NTW OUX PUX PUY NSX MQV LPS KNR
- M KMP KMQ LPS LPT MQU NQU NPT NOR LOR LNQ LNQ KMP
- P LNR KOS MRU NSX RVX SWY TWZ TWZ SVY QVY MRU LPS
- Se LMU KMV KOW LPX MQX MSY NSY NSY MRX LQW KOU KMU
- Sw
- - Winter 12 1 2 Spring 3 4 5 Summer 6 7 8 Autumn 9 10 11
Tropical D PRU PST PTW PUX QVY TWZ VYZ VYZ UXY UVX RUW QSV
- F MUW LUW MUW OUX OUX QUX QUX QUX QUX PUX OUW MUW
- H MPR NPT NRT PRU PTX QUY SWZ SWZ SVY QTW ORU NQT
- M MPR NPS NQT OQT OQU OQU NPT NPT NPT NPS MPS MPS
- P MPR NQT NRU PRU RWY TWY TWZ TWZ TWY RVY PSW NRU
- Se PSU PSV OTW QTX QTX RTY RTX RTX RTW QSV QSV PRV
- Sw

The temperature figures for desert assume an elevation of sea level; for plains && forest, 500 feet; for hills, 2000 feet; and for mountains, 4000 feet.

If these terrain types exist at different elevations than the ones given, subtract 3 degrees from the temperature
figures for every increase of 1000' (or +add+ 3 degrees for
every decrease of 1000') if a more accurate temperature
determination is desired.

Temperature Letter Codes
Letter High Low Letter High Low Letter High Low Letter High Low
A -20 -40 H 30 15 O 70 55 U 90 70
B -15 -30 I 35 15 P 75 55 V 90 75
C -5 -20 J 40 20 Q 80 60 W 95 75
D 0 -10 K 50 30 R 80 65 X 100 80
E 10 0 L 60 40 S 85 65 Y 105 80
F 18 10 M 65 45 T 85 70 Z 115 85
G 25 10 N 70 50 - - - - - -

<finish colors?>

<note: from here on in, the alphanumerics have been added into the sections>

A1: How to Use the Temperature Variation Table

Each terrain/climate type is represented by a set of twelve <12>
three-letter codes that describe the general temperature conditions <3>
of that AREA during each month of the year. The first letter <1st>
identifies the lowest temperatures that will normally occur; the
third letter identifies the highest temperatures that will normally
occur, and the second letter represents the mean, or avg.,
high && low temperatures for that AREA.
    e.g., the code
    for a sub-tropical plains AREA in the seventh month of the year <7th>
    (early summer) is T W Z.
    The T indicates that the lowest temperature during that month will almost never be lower than 70;
    the Z indicates that the temperature can rise as high as 115 on the hottest days;
    and the W indicates that on most days,
    the high temperature will be 95 and the low temperature 75.

At the beginning of an adventure or an episode (such as when
PCs find themselves abruptly transported to a different
AREA), USE the second letter to ascertain the current temperature
conditions. From this starting point, the temperature will
MOVE up || down on a daily basis according to the results of the
Day-to-Day Change Table (below).

As a general rule, the lowest temperature of the day will occur
just bef. sunrise, and the  will gradually rise until the
high temperature for the day is reached in early afternoon. After
possibly remaining at the high point for a few hours (DM's discretion),
the  will decrease gradually through the evening
&& night until the next low point is reached just bef. sunrise
on the following day. Of course, this general rule should be modified
or disregarded in special weather conditions or when the
DM judges that different times for high && low temperatures should prevail.

Table A2: DAY-TO-DAY CHANGE
Dice Roll Temp. Change Chance of 
Precipitation		 Wind Conditions
2 -3 steps yes Very strong **
3 -2 steps no From arctic, + 15 mph *
4 -2 steps yes From arctic, + 10 mph *
5 -1 step no Prevailing direction, + 15 mph *
6 -1 step yes Prevailing direction, + 10 mph *
7 no change same Same as previous day
8 +1 step yes Prevailing direction, -10 mph
9 +1 step no Prevailing direction, -15 mph
10 +2 steps yes From tropics, -10 mph
11 +2 steps no From tropics, -15 mph
12 +3 steps yes Very slight **

* -- Wind velocity in arctic and tropical climatic regions does not exceed 20 mph exc. in special conditions;
in subarctic climate,
25-30 mph is the normal maximum.

** -- Consult Table A4: Special Weather <slight variance in transcription: this format is continued throughout>

A2: How to Use the Day-to-Day Change Table
    Roll 2d6 for each day beyond the present one,
either by day as needed or for a number of days in succession as desired.
Use two dice that are different in color or size,
so that they can be designated as "die 1" and "die 2."
This distinction is important
whenever there is a chance of precipitation, as explained below.

    Follow the instructions below for how to interpret each category
on the Day-to-Day Change Table.

Temperature Change: MOVE up or down the letter scale as required
to ascertain what the next day's high && low temperatures
will be be. If the present temperature is within the allowable
range (as indicated by the first && third letters of the Temperature Code) <1st && 3rd>
but a MOVE dictated by this table would take the result
beyond that range, then stop whent he extreme result is reached.

Example: The current temperature in a subarctic forest in the first month of winter is H, and the 2d6 roll yields a 12.
Instead of going up three steps (to K, which is beyond the upper limit), increase <3>
the temperature to J for the following day.

    If the current temperature is already at the upper limit,
treat any "plus" result as "no change" and treat a roll of 7 id. as a roll of 6 --
that is,
the temperature drops by 1 step and precipitation is possible.
If the temperature remains at the upper limit for two consecutive days,
treat a roll of 7 or 8 as a roll of 6,
and continue this pattern until the streak of hot weather ends.
(For a streak of cold weather, perform id. process with the other
end of the table.)

Chance of Precipitation:
If the dice roll indicates a "yes" result in this column,
note the numbers that came up on die 1 and die 2 and consult Table A3: Precipitation Variation.

Wind Conditions:
  -   -   -

Atroa (goddess of the east wind)
Sotillon (goddess of the south wind)
Telchur (god of the north wind)
Wenta (goddess of the west wind)

On a dice roll of 3 through 11,
this column is used to determine the direction and velocity of the wind.
Note that a wind from the arctic will be a N wind in the northern hemisphere
and a S wind in the southern hemisphere; the esrever
is true for a wind from the tropics. The "prevailing direction" is as
described above in the .txt for the various climatic regions.
The velocity increment (+ 15 mph, + 10 mph, etc.) is added to the wind velocity for the previous day.
Obviously,
wind velocity cannot fall below zero,
and exc. in special circumstances it will not increase beyond 45 mph.
Exceptions to this rule for arctic, sub-tropical, and sub-arctic
climates are noted beside the Day-to-Day Change Table.

Wind velocity represents the highest SPEED the wind will reach
on the day in , during gusts that can last anywhere from
a few seconds to a few minutes. For the REST of the day, the wind
SPEED will be no more than half of the indicated max. velocity. <1/2>
For example,
the maximum wind velocity for the present day has been determined as 15 mph.
A roll of 3 on Table A2: Day-to-Day Change indicates that the maximum velocity for the following day will be 30 mph.
This means that gusts up to 30 mph will occur (at times determined by the DM),
but in general the wind speed on the following day will average about 15 mph.

If precipitation occurs on a given day, the max. wind
SPEED for that day will usu. occur immed. bef. && during
the precipitation. The current wind SPEED can serve as
an indicator of how long the precipitation lasts: On a very windy day,
the precipitation will usu. occur over a short duration; the
clouds containing the rain || snow will be moving rapidly through
the upper atmosphere. On a relatively calm day, the rain clouds
MOVE more slowly, and precipitation that occurs in a certain loc.
will usu. be less intense and more prolonged.

If the dice roll on Table A2: Day-to-Day Change is 2 or 12,
follow the normal procedure for determining temperature change,
chance of precipitation,
and wind conditions,
and then refer to Table A4: Special Weather <(page 112)> to see if some extraordinary weather occurs on the day in question.

Table A3: PRECIPITATION VARIATION
- - Winter A B C Spring A B C Summer A B C Autumn A B C
Arctic D - T - - T - - T - - T -
- H - - T - - T - - T - - T
- M - - T - - T - - T - - T
- P - T T - L T - M L - T T
- Se - T - - L T - L T - L T
- - Winter A B C Spring A B C Summer A B C Autumn A B C
Subarctic D - T - - - T - - T - T -
- F - L T T M L T M L T L T
- H - T T - L T T L L - L T
- M - T T T M L T L T - L T
- P - L T T M L T M L T L T
- Se - T T - L T T M L - L T
- Sw - L T T M L T L L T L L
- - Winter A B C Spring A B C Summer A B C Autumn A B C
Temperate D - T - - T - - T - - - -
- F T M L L H M L M M L M M
- H T M L L H M L H M T M L
- M - M L - M L - L T - M L
- P - L T L H M L H M T M L
- Se L H M T M L - L T L H M
- Sw T M L L H L L H M - M L
- - Winter A B C Spring A B C Summer A B C Autumn A B C
Subtropical D - T - - T - - - - - T -
- F M H H M D H M D H M H H
- H T L L L H M L H M T M L
- M T M L L H M L M M T M L
- P - L T T H L T M L - L T
- Se T M L L H M L D M - L T
- Sw T L L T M L T H L T L L
- - Winter A B C Spring A B C Summer A B C Autumn A B C
Tropical D - T - - L T - T - - T -
- F M D H M D H M D H M D H
- H - T - - L T T M L - T -
- M T M L M H H T M L M H H
- P - T - L H M M H M L H M
- Se - T - L D M H D D - L T
- Sw - L T M H H M H M L M M

Precipitation Letter Codes
- = No precipitation
T = Trace (less than 1/8" rain or 1/2" snow)
L = Light (up to 1/2" rain or 1" snow)
M = Moderate (up to 3/4" rain or 2" snow)
H = Heavy (up to 1 1/2" rain or 4" snow)
D = Downpour (more than 1 1/2" rain)

A3: How to Use the Precipitation Variation Table
    If the roll of 2d6 on Table A2: Day-to-Day Change is an even number,
you must refer to Table A3: Precipitation Variation to determine whether precipitation occurs and,
if so,
how much rain or snow will fall during the next 24 hours.

    Cross-index the appro. climate/terrain combo w/
the current season.
Take the result for column A under the season if die 1 is greater than die 2;
use the result under column B if the dice are equal;
and use the result under column C if die 2 is greater than die 1.

    A result from this table indicates the amount of precipitation
that will fall during the entire day to come. Exactly when the precipitation
occurs and how long it lasts are matters ultimately left
to the judgement of the DM. For instance, a heavy accumulation
of rain could be the result of a day-long sprinkle or it
could all fall in less than half an hour during a storm. (For some <1/2>
guidelines on the duration && intensity of precipitation related to
wind velocity, see the .txt above on Wind Conditions.)
 

Rain, Sleet, or Snow
To determine in what form precipitation falls,
use this general guideline:
If the current temperature is 36 degrees or higher,
rain will fall.
If the temperature is between 30 and 35 degrees inclusive,
sleet will result half of the time (1-3 on d6, or DM's discretion) and snow the other half.
At a temperature lower than 30 degrees,
the precipitation will be a snowfall.
 
 
Tlaloc (god of rain) Chih Sung-Tzu (god of rain) Indra (god of rain) Beory (goddess of rain) -

 

Collecting Precipitation
Of course, it is psb. for characters to attempt to collect precipitation
in containers and USE it for drinking water. When this
occurs, it is fairly simple for the DM to calculate how
much water can be obtained as long as the dimensions of the
container are known.
For liquid collected in a circular container,
the volume of the cylinder of water so obtained is pi x r2 x h,
where pi is a constant (roughly equal to 3.14),
r is the radius of the container and
h is the depth of the water collected.
Thus,
one inch of rain collected in a 6-inch-radius container yields about 113 cubic inches of water.
Since an ounce of water occupies about 1.8 cubic inches in volume,
the container holds about 63 ounces of water,
or roughly one-half gallon.

If water is collected in a square || rectangular container, the
volume of the liquid is simply the product of the measurements of
all three dimensions. <3>
If a metal box measuring 6 inches long by 4 inches wide by at least 1 inch deep is left open during a 1-inch rainfall,
the box will contain 6 x 4 x 1,
or 24,
cubic inches of water.
This amounts to roughly 13 fluid ounces,
which is somewhat less than a pint.

Melted snow converts to water at a rate of 10 to 1 ;
that is,
1 inch of fresh snow,
if it is collected and melted,
will yield id. amount of liquid as a rainfall of 1/10 inch.
However, this fact is not
esp. relevant to the subject of collecting liquid for drinking.
In most cases when a snowfall occurs, the precipitation will stay
on the ground, from where it can be easily gathered and put into a
container. And more often than not, there will already be snow
cover on the ground that can be scavenged whenever drinking
water is needed. For obvious reaosns, it is not difficult for characters
to obtain needed drinking water during the snowy season in
any climate that has one.

Following are some general descriptions of the intensities of
precipitation to USE as guidelines for certain seasons and terrain/climate
types. In this section of .txt, "rain" refers to precipitation
in general, not just the liquid form, unless otherwise specified.

Trace precipitation accumulates to a measureable amount only
if the rain falls continuously for at least half an hour. In a desert, <1/2>
only one out of every ten trace rainfalls will last more than a few <1 out of every 10>
minutes, and any liquid precipitation that does fall will quickly
soak through the sandy || rocky soil -- or evaporate (in hot temperature)
almost as quickly.
Collecting the water from a trace rainfall is fruitless exc. in cases of dire need:
the heaviest possible trace accumulation,
just short of 1/8 inch of rain,
even if collected in something as large as a cooking pan 1 foot in diameter,
will yield less than 8 fluid ounces of liquid.

Light precipitation should be interpreted very conservatively in
terrain/climate areas where it reprezents the greatest amount of
rain || snow that normally falls in a day. Most of the light rainfalls
or snowfalls in such an AREA will be scarcely greater than trace precipitation.
The converse does not apply in an AREA where light
reprezents the least precipitation psb; in such a case, the accumulation
can range through the entire span of possibilities.

Moderate precipitation does not always fall under moderate
conditions. The amount may be the result of continuous drizzle
for most or all of a day, or it may all come down in a storm of only a
few minutes' duration. In a climate/terrain AREA where moderate
reprezents the greatest amount of precipitation that can normally
fall, the accumulation will usu. not be much greater than light,
and most of the time it wall fall as gentle, prolonged rain instead of
coming down quickly in a brief storm.

Heavy precipitation almost always falls in a relatively short time
as the result of storm conditions, and in most cases those storm
conditions will occur at dawn || dusk -- within two hours either <2>
way of sunrise || sunset. This is in contrast with the lighter
amounts of accumulation, which can occur at any time of the day || night.

Downpour precipitation occurs in certain terrain in sub-tropical
&& tropical climates. Typically there is a period of intense rain,
during which as much as an inch of water may fall in a half-hour or <1", 1/2>
or less (at any time of the day || night), sandwiched between two <2>
periods of lighter, more prolonged precipitation.

Extraordinary Precipitation

Whenever two successive rolls on Table A2: Day-to-Day Change are doubles,
and no special weather occurs on either day,
then there is a 50% chance (1-3 on d6, or DM's discretion) that the precipitation for the second day will be one step greater than the result given on Table A3: Precipitation Variation for a roll of doubles.

e.g., it is summer in a forest AREA.
The roll for the day was double 4's,
indicating a day on which a moderate amount of rain falls.
The roll for the next day is double 3's,
and a subsequent roll of a six-sided die results in a 3,
indicating a day of heavy rainfall (one step greater than moderate).
If the d6 roll is 4 or higher,
the precipitation remains moderate for the coming day.

If doubles are rolled more than twice in succession, the precipitation
does not continue to increase, but remains at the
"one step greater" level; a downpour will never occur during
summer ina temperate forest, regardless of how many times in a
row the dice come up doubles.
Thus, the 1-in-3 chance <should be: 50% chance> does not have to be checked if doubles are rolled more than twice in a row.
In no case can xtraordinary precipitation xceed the level of a
downpour.

Table A4: SPECIAL WEATHER
- - Winter 1st 2nd 3rd 4th Spring 1st 2nd 3rd 4th Summer 1st 2nd 3rd 4th Autumn 1st 2nd 3rd 4th
Arctic D G A D D G A D D G A D D G A D D
- H G A D D G A D M G A D Z G A D D
- M G A D D G A D M G A M Z G A D M
- P G A D D A G D M X A D Z G A D Z
- Se G A D D A G M Z G A M Z G A M Z
- - Winter 1st 2nd 3rd 4th Spring 1st 2nd 3rd 4th Summer 1st 2nd 3rd 4th Autumn 1st 2nd 3rd 4th
Subarctic D G A D D G A D D A S D D G A D D
- F G A D Z A X D Z X A Z D A X M D
- H G A M D A G D Z A X Z D G A M D
- M G A D M A X M Z A X Z D G A M D
- P G A M D A X D Z Z A Z D G A D Z
- Se G A M Z G A M Z X A Z M A G M Z
- Sw A X M Z A X M Z X A Z M A X M Z
- - Winter 1st 2nd 3rd 4th Spring 1st 2nd 3rd 4th Summer 1st 2nd 3rd 4th Autumn 1st 2nd 3rd 4th
Temperate D A S D Z G S D Z G S D Z S G D Z
- F A X M Z G X M Z G X M Z A X M Z
- H A X M Z A X Z T A X D Z A X D Z
- M A X M D A X M Z A X D Z X A D Z
- P A G D Z A X T Z X G D Z X A D Z
- Se A X M Z C X M Z C X M Z A X M Z
- Sw A X M Z G X M Z G X M Z A X M Z
- - Winter 1st 2nd 3rd 4th Spring 1st 2nd 3rd 4th Summer 1st 2nd 3rd 4th Autumn 1st 2nd 3rd 4th
Subtropical D A S D Z G S D Z G S D Z G S D Z
- F X A M Z X G Z M X X Z M A X M Z
- H A X D Z A X D T X G D Z A X Z M
- M A X D Z A X Z M X G Z D X A Z M
- P A X D Z X G Z T X G D Z G A D Z
- Se A X D Z C X M Z C X M Z C X D Z
- Sw A X D Z C X M Z C X M Z C X D Z
- - Winter 1st 2nd 3rd 4th Spring 1st 2nd 3rd 4th Summer 1st 2nd 3rd 4th Autumn 1st 2nd 3rd 4th
Tropical D A S D Z G S D Z G S D Z G S D Z
- F X X M Z X X Z M X X Z M X X M Z
- H A G D Z G X D Z G X D Z G G Z D
- M A X M Z A X M Z X G Z M A G M Z
- P G X D Z G X D Z S X Z D G X Z D
- Se X A D Z A X M Z C X M Z X A Z M
- Sw A X Z D G X Z M X G M Z X A M Z

Special Weather Codes
A = Cold Wave
C = Cyclone/Hurricane/Typhoon
D = Drought
G = Gale
M = Mist or Fog
S = Sandstorm/Dust Storm/Blowing Snow
T = Tornado
X = Extreme Precipitation
Z = Heat Wave

A4: How to Use the Precipitation Variation Table
    Consider the earlier roll on Table 2: Day-to-Day Change (either a 2 or a 12) as Roll 1,
and then roll 2d6 again,
referring to the result as Roll 2.
Cross-index the appro. climate/terrain combo
w/ the current season of the ear on the Special Weather Table to
obtain the four-letter code that indicates what <4>
kinds of special weather are psb. Then check the table
below to determine what special weather (if any) occurs:

                    .........................................Roll 2 ..................................................
Roll 1 2-4 5-6 7 8-9 10-12
2 1st 2nd 2nd - -
12 - - 3rd 3rd 4th

The notations "1st, 2nd, 3rd, 4th" refer to a single letter of the four-letter code.
For example,
if Roll 1 was a 2 and Roll 2 is a 6,
the second letter of the four-letter code indicates what sort of special weather will occur.
A result of "--" on the above table indicates
that no special weather occurs. To determine what
conditions prevail on the day in , refer to the following
section of .txt.
Many episodes of special weather span more than a single day;
while such an episode is still running its course,
treat any roll of 2 or 12 on Table 2: Day-to-Day Change as No Special Weather.

Special Weather Definitions
 
No Special Weather (-) Cold Wave (A) Cyclone/Hurricane/Typhoon (C) Drought (D) Gale (G)
Mist or Fog (M) - Sandstorm/Dust Storm/Blowing Snow (S) - Tornado (T)
EXTREME PRECIPITATION (X) Hailstorm (H) Ice/Sleet Storm (I) Lightning Storm (L) Severe Snowstorm (S)
Heat Wave (Z) - - - THE WORLD OF WEATHER

No Special Weather (--):
If the roll on Table 2: Day-to-Day Change was a 2 but no special weather occurs,
then the prevailing condition for the day in question is very strong wind (as given on Table 2: Day-to-Day Change).
This is a wind that gusts up to 45 mph,
accompanied by a sharp decrease in temperature and a chance of precipitation
(check the "B" column for the appropriate season on Table 3: Precipitation Variation).
The wind will come either from the arctic or from the prevailing direction (50% chance of each, or DM's choice).

If the roll on Table 2: Day-to-Day Change was a 12 but no special weather occurs,
then the day's weather is marked by a very slight wind plus a sharp increase in temperature and a chance of precipitation
(check the "B" column on Table 3: Precipitation Variation).
A very slight wind is one that occas. gusts up to
5 mph, but for virtually all of the day in  the wind is calm,
or so slight that it has no effect on the surroundings.

Cold Wave (A):
For the next 3-8 days (1d6 + 2),
starting with the day in question,
the temperature will drop at the rate of 4 steps per day until it reaches a low point one step below the minimum temperature.
Roll on the Day-to-Day Change Table as
usu. each day, but disregard the Temperature Change column
for the duration of the cold wave. When the temperature drops to
one step below the normal min., it will remain at taht level for
the duration of the cold wave.
If the normal minimum temperature level is "A" (high of -20, low of -40),
the lowest possible temperatures during the cold wave will be 10 degrees colder (high of -30, low of -50),
and the cold wave will only last for at most three days after the temperature falls to this level
(counting the day on which the extra-low temperatures first occur),
regardless of the result of the roll for duration.
When the cold wave ends,
the temperature will automatically rise to the normal minimum on the first day thereafter,
and will rise even higher if the roll on Table 2: Day-to-Day Change is 7 or greater.

For example: It is the first month of spring in a temperate mountain region,
and the temperature for the current day is K (high of 50, low of 30).
The tables indicate that a cold wave will begin on the following day,
and a roll of 3 on 1d6 determines that the cold wave will last for 5 days.
On the following day the temperature will drop by 4 steps,
to G (high of 25, low of 10).
On the second day of the cold wave,
the temperature will fall only 3 more steps,
to D (high of 0, low of -10) because this is one step lower than the normal minimum temperature at this time of year for this terrain/climate combination.
The temperature will remain at level D for two more days thereafter until the cold wave breaks. <2>
If a 7 or higher is rolled on Table 2: Day-to-Day Change for that day,
the temperature will go up an additional 1, 2, or 3 steps.
If a 6 or lower is rolled,
the temperature remains at level E,
since this is the lowest the temperature can be under normal circumstances.

Cyclone/Hurricane/Typhoon (C):

This ferocious storm is known by
different names in different areas of our world -- but no matter
what it is called, it is one of the most fearsome and potentially
lethal fo all weather phenomena.
The wind velocity in a hurricane can be from 80 to 180 mph (1d6 x 20 + 60),
strong enough to damage even stone structures.
Any characters or creatures not in places
of secure shelter when the storm hits are in danger of literally
being blown away.

One day before a hurricane actually reaches land in a seacoast AREA,
the AREA will be drenched by a lightning storm (se the secion
below on Extreme Precipitation for the description fo this
storm). If characters sense that things are going to get worse bef.
they get better, and if they are able to MOVE far enough inland
during the first day, they may be able to avoid the full fury of <1st>
the hurricane but they probably won't be able to MOVE out of the
path of the storm altogether.
A hurricane will not move farther than 10 miles inland,
but the storm around its perimeter will extend at least another 50 miles inland.

A hurricane moves in a general direction away from the equator.
After it hits land,
it will follow the coastline for 1 or 2 days bef. veering back out to sea.
The storm is accompanied by
torrential rain, up to twice as heavy as downpour precipitation.
In +addition+, the wind of the hurricane drives sea water ahead of it,
forming a tidal wave that can flood low-lying areas as far as 3 miles
inland.

Hurricane winds revolve around a central calm AREA, known as
the "eye". After spewing forth winds && rain in a certain AREA for
six hours, the storm will abruptly subside as the eye passes over <6>
the loc. that only minutes earlier was being ravaged &&
drenched. The sky will clear partially || entirely and wind velocity
will DROP to practically zero. <0>
Then,
after 30 or 60 minutes,
the storm will mount to its full fury again as the second half of the disturbance passes over the AREA.
Six hours later, the hurricane will
have passed, and "only" a vigorous rainstorm will remain for the
next few hours until the storm center moves entirely out of the
AREA.

For three days in a row beginning with the day the hurricane <3>
hits, the Day-to-Day Change Table is not used. On the day of the
hurricane, the temperature will remain constant, and precipitation &&
wind SPEED will be as described above. For two days after <2>
the hurricane, the temperature will not vary by more than one <1>
step either way from the temperature on the day of the storm.
(Roll 2d6: 6 or less = 1 step down; 7 = no change; 8 or more = 1 step up.)
During those two days there will be no precipitation,
and wind velocity will not be greater than 10 mph (from the prevailing direction).

A hurricane will not occur in id. general AREA (within a 200-mile radius) more often than once a month.
If the tables indicate
the occurrence of a second hurricane in id. AREA bef. <2nd>
one month has elapsed, treat it instead as an occurrence of
extreme precipitation (see below).
Also,
a hurricane will not occur in the tropics within 5 degrees of latitude north || south of the equator;
disregard any "C" result obtained on Table 4: Special Weather if it pertains to a location in this AREA.

Drought (D):
For a period of 4-14 days (2d6 + 2),
the usual principles governing frequency and amount of precipitation do not apply.
On the first day of a drought no precipitation will fall, regardless <1st>
of what the Day-to-Day Change Table has indicated. At
any time when trace precipitation is indicated, no rainfall || snowfall
will occur. In an AREA where light || moderate precipitation is
the normal max., no precipitation greater than a trace
amount will fall, and this will occur no more than once in every
span of five full days. In +addition+, any trace result is disregarded. <5>
In an AREA where heavy precipitation is the normal max.,
treat any precipitation result as two steps lower than actual, so <2>
that H becomes L, M becomes T, and L becomes no precipitation.
Use the Day-to-Day Change Table normally for temperature
&& wind, but amend any precipitation results as described here.

Example 1: It is winter in an area of subtropical hills,
and the tables indicate that a drought will occur beginning on the following day.
A roll of 2d6 yields a result of 9,
so the drought will persist for 11 days.
No rain will fall on the first day. <1>
When light precipitation
is indicated on the second day, a trace of rain falls instead. <2nd>
Since precipitation can only occur once in a five-day period,
it will not rain again until day 6 of the drought at the earliest.

Example 2: The season is spring instead of winter,
which means that the precipitation amount in sub-tropical hills normally ranges from light to heavy.
During a springtime drought, any
heavy precipitation result is treated as light rain, and in any other
instance only trace precipitation will occur if it rains at all.

Gale (G):
This is an extremely strong wind,
usually ranging from 45 to 75 mph (1d6 x 5 + 40),
which is almost always accompanied by precipitation.
When rain || snow does occur along w/
gale-force winds, the result can be almost as perilous as a hurricane.
For a period of 2-7 hours (1d6 + 1),
gale-force winds will never drop below 30 mph and will almost always be 50 mph or greater.
If the wind velocity was 20 mph or greater on the previous day,
then the gale-force winds on the current day will range from 50 to 70 mph.
If a gale occurs in a desert AREA, no precipitation
will fall on id. day; instead, the wind will bring about a
severe sandstorm. Also in an arctic || sub-arctic environment
when snow is on the ground, gale-force winds will whip the snow
up && around, causing conditions similar to those of a severe sandstorm.
See the description for Sandstorm/Dust Storm/Blowing Snow below
for more info on this phenomenon.

Mist or Fog (M):

The "calmest" form of special weather, mist || fog
is nevertheless not be be taken lightly.
It will occur beginning either at sunrise (1-4 on 1d6) || sunset (5-6 on 1d6) and will last for a # of hours equal to the result on this die roll.
Fog will be
heavy whenever it occurs in a seacoast AREA or in an inland loc.
adjacent to a body of water; in all other locations, it will be of
moderate intensity.

If precipitation occurs on id. day, the rain || snow will not fall while the fog condition persists,
but it is likely (50% chance, or DM's choice) that a period of precipitation will immediately follow or precede the fog
(the former case for a daytime fog, the latter for a nighttime fog).

The effects of fog on movement are covered in the section on
Encumbrance && Movement; the effects of fog on visibility are
covered in the section on Vision && Visibility.

Sandstorm/Dust Storm/Blowing Snow (S): This phenomenon
occurs in a desert environment where the top layer of soil is loose
|| sandy in consistency, or in a cold environment where the
ground is covered by a thick layer of loose snow.
Regardless of what the result on Table 3: Precipitation Variation indicates,
no precipitation will fall on the day that a sandstorm occurs;
instead,
the very strong winds will pick up the loose soil (or snow),
and for a period of 2-5 hours (1d4 + 1) the rapidly moving air will be filled with particles that inhibit movement and reduce visibility,
and may even cause damage to unprotected characters or creatures.
A severe sandstorm occurs whenever gale-force winds are indicated
for a desert environment, or an arctic || sub-arctic environment
where snow is on the ground.
This condition will last for 2-7 hours (1d6 + 1),
and only the very hardy or the very foolish will attempt to do anything other than seek shelter and wait out the storm.

Tornado (T):
In terms of the AREA it directly affects, a tornado is
the most dangerous && destructive of all natural weather phenomena.
When a "T" result is indicated on the Special Weather Table,
this means that conditions suitable for the development of
tornadoes will arise during the day in .
The temperature will rise to at least two steps above the normal temperature for the AREA in 
(if the roll of 12 on Table 2: Day-to-Day Change did not increase it to this level already),
and for 1d3 hours bef. tornadoes pass through the area the winds will be very strong and heavy precipitation will occur.
Then the rain will stop
abruptly, tapering to nothing or a traceamount within minutes,
and in the AREA immed. around a tornado's path (one-half <1/2>
mile on either side) the wind will DROP off to slight || very
slight velocity.
The tornado will come through the area 3d6 minutes after the start of the cessation of this activity.
During this time and for about 30 minutes after the tornado passes,
the temperature will drop abruptly by 15 degrees or three steps,
whichever is greater.
After this "cooling-off peroid," the temperature will begin
to rise again until it reaches an appro. level according to
what was pre-determined for the day. FOr the REST of the day after a
tornado comes through an AREA, the weather will be calm &&
non-threatening -- a strange (and usu. welcome) contrast to
what has just happened.

The path of a tornado when it touches the ground is typically one-quarter mile wide and about 15 miles long,
and most tornadoes travel along the ground at about 40 mph.
The whirling vortex of air is distinguishble from the surrounding sky, esp.
near the ground where the cloud contains dirt && debris that it
has picked up in its rampage across the countryside. Within and
around the whirlwind, the velocity of the spiralling air ranges from
200 to 300 mph. Because of the centrifugal force pushing the air
outward from the center, the air pressure in the center of the vortex is
considerably lower than in the surrounding vicinity. Structures
that are able to stand up to the high-velocity winds may still be destroyed --
virtually exploded -- when this AREA of extremely low
pressure passes over their loc..

Extreme Precipitation (X):
This category encompasses several phenomena.
The particular type of storm that occurs depends on
climatic region, temperature, and a die roll.
Cross index the appropriate conditions on the table below and roll d6 to determine what kind of extreme precipitation occurs:

                                                    .....................................................................Climatic Region...............................................................................................
Temperature Tropical/Subtropical Temperate/Subarctic/Arctic
-1 or lower - S (1-3) or none (4-6)
0 to 9 - S (1-5) or none (6)
10-29 - S (1-5) or I (6) *
30-35 H (1-6) S (1-4) or H (5) or I (6)
36-49 L (1-5) or H (6) L (1-4) or H (5-6)
50-74 L (1-6) L (1-5) or H (6)
75 or higher L (1-6) L (1-6)

Extreme Precipitation Letter Codes
H = Hailstorm
I = Ice/Sleet Storm
L = Lightning Storm
S = Severe Snowstorm

* -- An Ice/Sleet storm will only occur if the temperature is 25 degrees or higher;
otherwise, treat a roll of 6 as "none."

    Hailstorm (H):
    This kind of activity usually occurs during the first ten minutes of a lightning storm <(see below)>,
    but on rare occaisons (roll of 1 on 1d6) can be a storm in and of itself lasting from 5-10 (1d6 + 4) minutes.
    Hail consists of lumps of ice,
    typically no larger than 1/4 inch in diameter but possibly as large as 2 or 3 inches across.
    When a hailstorm occurs at a temperature of 40 degrees or higher,
    the hail will melt within minutes of hitting the ground. If the hail
    activity is followed by a lightning storm, the pellets will ahve
    melted by the time the lightning storm ends.

    Ice/Sleet Storm (I):
    Sleet is frozen or nearly frozen rain,
    formed when snow falls from a high altitude and passes
    through a layer of warmer air on its way to the ground. The
    warmer air melts the snow crystals back into droplets of water,
    and the water freezes during the remainder of its descent.
    When the sleet hits the ground,
    it will coat anything it touches;
    by the time the storm passes,
    stationary and inanimate objects may carry a coating of ice up to 1/2 or 3/4 inch thick.

    Depending on it's intensity,
    an ice storm will last from 20 minutes (if it occurs as heavy precipitation) up to two hours (if it occurs as trace precipitation).
    Of course, the longer the
    storm, the heavier the coating of ice that will result.

Lightning Storm (L):
    A lightning storm, or thunderstorm,
    can occur as a separate phenomenon in && of itself or as
    the beginning stage of a longer rainstorm.
    If a lightning
    storm is indicated for a day on which moderate || light precipitation
    is supposed to fall, the the storm will occur by itself
    (and the moderate || light result is disregarded. If a
   downpour precipitation is supposed to fall, then the storm
    will occur at the beginning of the period of precipitation.
    A typical lightning storm lasts for 25 minutes,
    during which 3/4 to 1 inch of rain is dropped and the sky is lit up at freq. intervals by bright flashes of lightning.
    Roughly half of all thunderstorms occur within two hours either way of sunrise <1/2, 2>
    or sunset.

   Wen Chung (god of thunderstorms)

Severe Snowstorm (S):
    If the normal maximum precipitation for the day is moderate,
    this storm will dump 5-10 inches (d6 + 4) of snow;
    if the normal maximum precipitation is heavy,
    a severe snowstorm will cause 7-12 inches (1d6 + 6) of accumulation.
    The snow will come down at the rate of 1 inch per hour until the indicated accumulation is reached.
    Wind velocity will be very strong at the start of the storm,
    but will taper off after 1 or 2 hours to a moderate breeze (15-20 mph)
    at best as the storm center becomes stalled over the area receiving the precipitation.

Heat Wave (Z):
For the next 3-8 days (1d6 + 2), starting with the day in question,
the temperature will rise at the rate of 4 steps per day until it reaches a high point one step above the normal maximum temperature.
Roll on the Day-to-Day Change Talbe as usu.
each day, but disregard the Temperature Change column for the
duration of the heat wave. When the temperature rises to one <1>
step above the normal max., it will remain at that level for
duration of the heat wave.
If the normal maximum temperature level is "Z" (high of 115, low of  85),
the highest possible temperature during the heat wave will be 10 degrees hotter (high of 125, low of 95),
and the heat wave will only last for at most 3 days after the temperature rises to this level
(counting the day on which the extra-high temperatures first occur).
When the heat wave ends,
the temperature will automatically fall to the normal maximum on the first day thereafter,
and will fall even lower if the roll on Table 2: Day-to-Day Change is 7 or less.

For example: It is the first month of spring in a temperate mountain region,
and the temperature for the current day is K (high of 50, low of 30).
The tables indicate that a heat wave will begin on the following day,
and a roll of 3 on d6 determines that the heat wave will last for 5 days.
On the following day the temperature will rise by 4 steps,
to O (high of 70, low of 55).
On the second day of the heat wave,
the temperature will rise only 3 more steps,
to R (high of 80, low of 65) because this is one step higher than the normal maximum temperature at this time of year for this terrain/climate combination.
The temperature will remain at level R for
two more days thereafter until the heat wave breaks. <2>
On the first <1st>
day after the heat wave, the temperature will automatically fall
one step, to Q. <1>
If a 7 or less is rolled on Table 2: Day-to-Day Change,
the temperature will fall an additional 1, 2, or 3 steps.
If an 8 or greater is rolled,
the temperature remains at level Q,
since this is the highest the temperature can be under normal circumstances.

OPTIONAL RULES
 

Relative Humidity

    This figure, expressed as a %percentage%, describes the amount
of water vapor in the air at a given temperature compared to the
max. amount of water vapor the air could hold at that temperature.
The warmer the temperature, the more water vapor the air can hold:
air with a relative humidity of 100 percent is considerably "wetter" at a temperature of 80 degrees than it is at a temperature of 50 degrees.

    Humidity can have a significant effect on the ability of characters
&& creatures to cope with the weather when temperature
&& humidity are both high, and particularly so when the wind is
slight || non-existent.

Table A5:  HUMIDITY VARIATION
- - Winter Spring Summer Autumn
Arctic (all terrain) L L L L
- - Winter Spring Summer Autumn
Subarctic D L L L L
- F L M M L
- H L L L L
- M L M L L
- P L M M L
- Se L M M L
- Sw L M M L
- - Winter Spring Summer Autumn
Temperate D L L L L
- F M H M M
- H M H H M
- M L M L M
- P M H H M
- Se H M M H
- Sw M H H M
- - Winter Spring Summer Autumn
Subtropical D L L L L
- F H H H H
- H M H H H
- M M H H H
- P M H M L
- Se M H H M
- Sw M H H M
- - Winter Spring Summer Autumn
Tropical D L L L L
- F H H H H
- H M M H M
- M M H H H
- P M H H H
- Se M H H M
- Sw M H H H

Humidity Letter Codes
    L = Low (21-40%)
    M = Medium (41-70%)
    H = High (71-90%)

A5: How to Use the Humidity Variation Table
The letter codes shew the prevalent levels of humidity for the
various terrain/climate combos during the different seasons
of the year. The humidity in a given AREA will fluctuate
through a range of three levels (one lower, the given level, and <3, 1>
one higher), depending upon the precipitation for the day in  (Day 1) <1>
and the precipitation for the following day (Day 2).
Thus, bef. the proper humidity for Day 1 can be known, the
general conditions for Day 2 must have been determined. Consult
the following table and assign the humidity for Day 1 according
to the conditions that apply.

                                ....................... Day 2 precipitation .................................
Day 1 precip: None L or T M or more
None -1 0 +1
L or T 0/-1 0 0/+1
M or more 0/-1 0/-1 +1/+2

    -1 = Humidity falls one level
    0 = Humidity level unchanged
    +1 = Humidity rises one level

Where two values are given,
the one bef. the slash indicates the humidity on Day 1 bef. that day's precipitation occurs,
and the one after the slash indicates the humidity after that day's precipitation --
in both cases using the humidity level at the end of the previous day as the base for this adjustment.

Note again that in no case can humidity rise || fall beyond the
three-level range for a given AREA. <3>
If low humidity falls one level,
the result is dry humidity (0-20%).
If high humidity rises one level,
the result is saturated humidity (91-100%).

Example 1:
The humidity at the end of the previous day was medium.
The weather for Day 1 includes an episode of moderate precipitation,
and a check for Day 2 indicates that heavy precipitation will fall on that day.
Thus,
the humidity on Day 1 is high bef. that day's precipitation falls,
and it rises to saturated after the precipitation has ended.

Example 2:
The humidity at the end of the previous day was saturated.
The weather for Day 1 includes an episode of light precipitation,
and a check for Day 2 indicates that no precipitation will fall on that day.
Thus, the humidity on Day 1 is saturated bef. that day's precipitation falls,
and it falls to high after the precipitation has ended.

The preceding xample points out a shortcoming of this system:
It does not accomodate the possibility that the humidity
will DROP off drastically after reaching the high || sturated level
on a day when significant precipitation (moderate || heavier) occurs.
When this possibility xists, common sense and the DM's
discretion must prevail. If a one-day DROP of two humidity levels <1>
(from saturated to medium, high to low, or medium to dry) seems
warranted, then the DM is fully entitled to make this ruling.

Humidity and Effective Temperature
At temperatures of 60 degrees and higher, humidity && wind SPEED can combine to alter the effective temperature.
In short,
the combo of relatively high humidity and relatively low
wind SPEED cna make it seem hotter than it actually is, and the effects
on characters && creatures operating in this effective temperature are
modified accordingly. If these rules for humidity are
used in the campaign, the DM should check the following table to
determine the effective temperature and USE this figure instead of
the actual temperature to ascertain the effects on characters &&
creatures (as outlined in the first section of this book). <1st>

Table A6: HUMIDITY AND EFFECTIVE TEMPERATURE

                                        ......................... Wind Velocity ..............................
Temp. & Hum. 0-10 11-20 21-30 31-45 45+
60-64 - - - - -
    Dry - - - - -
    Low - - - - -
    Med. +5 - - - -
    High +10 +5 - - -
    Sat. +10 +5 - - -
65-74 - - - - -
    Dry - - - - -
    Low - - - - -
    Med. +5 - - - -
    High +10 +5 - - -
    Sat. +10 +5 +5 - -
75-84 - - - - -
    Dry - - - - -
    Low +5 - - - -
    Med. +5 +5 - - -
    High +10 +5 +5 - -
    Sat. +15 +10 +5 - -
85-94 - - - - -
    Dry - - - - -
    Low +5 +5 - - -
    Med. +10 +5 +5 - -
    High +15 +10 +5 +5 -
    Sat. +20 +15 +10 +5 -
95+ - - - - -
    Dry - - - - -
    Low +10 +5 - - -
    Med. +15 +10 +5 +5 -
    High +20 +15 +10 +5 +5
    Sat. +25 +20 +15 +10 +5

A6: How to Use the Humidity and Effective Temperature Table
    Whenever the temperature is 60 degrees or highter,
find the entry in the left-hand column that corresponds to the current temperature and humidity.
Read across to the column corresponding
to the wind SPEED for the day in . If a # is given in
the place where the appro. row && column intersect, +add+
that # to the actual temperature to obtain the current effective temperature and
then determine the effects of temperature on
characters & creatures using this value instead of the actual
temperature.

Wind Chill

Anyone who has lived in an AREA where the temperature drops to 35° or lower has first-hand xperience with the phenomenon known as wind chill.
As the temperature falls and wind
SPEED increases, the effective temperature can DROP off drastically.
Certain temperatures that are tolerable or even enjoyable
in calm wind conditions can become dangerous or even potentially
F.A.T.A.L. when combined with a brisk || strong wind. It is wind
chill, more than temperature alone, that makes a cold clmate
dangerous to characters && creatures who find themselves exposed
to the elements. If only one set of optional weather rules is <1>
used in the campaign, it is strongly recommended that the Wind
Chill Table be the one. <1>

Table A7: WIND CHILL

                          .........................Wind Velocity................................................
Temp. 5 10 15 20 25 30 35 40
35 35 20 15 10 5 5 0 0
30 25 15 10 5 0 0 -5 -5
25 20 10 0 -5 -5 -10 -15 -15
20 15 0 -5 -10 -15 -20 -20 -25
15 10 -5 -10 -15 -20 -25 -30 -30
10 5 -10 -20 -25 -30 -35 -35 -40
5 0 -15 -25 -30 -35 -40 -45 -45
0 -5 -20 -35 -40 -45 -50 -50 -55
-5 -10 -25 -40 -45 -50 -55 -60 -65
-10 -15 -30 -45 -50 -60 -60 -65 -70
-15 -20 -40 -50 -60 -70 -75 -80 -80
-20 -25 -45 -60 -70 -75 -80 -85 -90
-25 -30 -50 -65 -75 -85 -90 -90 -95
-30 -35 -60 -70 -80 -90 -95 -100 -100
-35 -40 -65 -80 -90 -95 -100 -105 -110
-40 -45 -70 -85 -95 -105 -110 -115 -115
-45 -50 -75 -90 -100 -110 -115 -120 -120

A7: How to Use the Wind Chill Table
Simply cross-index the actual temperature with the max.
wind SPEED for the day in  to find the effective temperature
with wind chill taken into consideration. Then USE this effetive
temperature instead of the actual temperature to determine
effects on characters && creatures in the environment.
For temperatures lower than -45, extrapolate downward following the pattern given for the decrease in effective temperature from -40 to -45.
For wind speeds greater than 40 mph,
use the column for 40 mph;
greater wind speeds have little,
if any,
effect on chilling.

Hours of Daylight

http://www.antarctica.gov.au/science/cool-science/2009/mid-winter-light-show-in-antarctica

As noted at the start of these rules under the description of the
arctic climatic region, the # of hours of daylight && darkness
on a given day at a given loc. depend on the latitude of
the loc. and the time of year. USE the following table, or an
adapted version of it, to incorporate this phenomenon into the
campaign.

Table A8: HOURS OF DAYLIGHT
- Winter 1 2 3 Spring 4 5 6 Summer 7 8 9 Autumn 10 11 12
Arctic - - - - - - - - - - - -
90 0 0 0 24 24 24 24 24 24 0 0 0
80 0 0 11 24 24 24 24 24 15.5 5 0 0
70 0 7.5 11.5 16 22 24 24 18.5 13.5 9 3 0
- Winter 1 2 3 Spring 4 5 6 Summer 7 8 9 Autumn 10 11 12
Subarctic - - - - - - - - - - - -
65 3 8.5 11.5 15 19.5 21.5 20 17 13.5 9.5 5 3
60 6.5 9 11.5 14.5 17 19 17.5 16 13 10 7.5 6
55 7.5 9.5 11.5 14 16 17.5 16.5 15 13 10.5 8.5 7
- Winter 1 2 3 Spring 4 5 6 Summer 7 8 9 Autumn 10 11 12
Temperate - - - - - - - - - - - -
50 8.5 10 12 13.5 15.5 16.5 15.5 14.5 12.5 11 9 8
40 9.5 10.5 12 13 14.5 15 14.5 14 12.5 11 10 9.5
35 10 11 12 13 14 14.5 14 13.5 12.5 11.5 10 10
- Winter 1 2 3 Spring 4 5 6 Summer 7 8 9 Autumn 10 11 12
Subtropical - - - - - - - - - - - -
30 10.5 11 12 13 13.5 14 14 13 12.5 11.5 10.5 10
25 11 11.5 12 12.5 13 13.5 13.5 13 12 11.5 11 10.5
20 11 11.5 12 12.5 13 13.5 13 13 12 11.5 11 11
- Winter 1 2 3 Spring 4 5 6 Summer 7 8 9 Autumn 10 11 12
Tropical - - - - - - - - - - - -
15 11.5 12 12 12.5 12.5 13 13 12.5 12 12 11.5 11.5
10 11.5 12 12 12.5 12.5 13 13 12.5 12 12 11.5 11.5
0 12 12 12 12 12 12 12 12 12 12 12 12

A8: How to Use the Hours of Daylight Table


 

    Read down the left-hand column to the latitude designation
that most closely corresponds to the loc. in question, and
read across to the appropriate month of the year. The number
given at the intersection of the row and column represents the
number of hours of daylight on each day during the month in
question. For this purpose, "hours of daylight" is defined as the
length of time between sunrise && sunset on a given day.

A shorter,
simpler version of this table can be obtained by using only the middle row of figures for each climatic region
(the "80" l. for arctic, "60" for subarctic, "40" for temperate, "25" for subtropical, and "10" for tropical).
This avoids the need for the DM to keep track of latitude, instead being concerned
only with the climatic region for which the hours of daylight
are being determined.

Note that this table does not indicate the precise times of day at
which sunrise && sunset occur; if these determinations are important,
they can be arrived at logically (using midnight as the
midpoint of the nighttime period and noon as the midpoint of the
daytime period), or they can be stipulated by the DM based on either
real-world xperience or the particular characteristics of the
campaign world.
 

Lydia (goddess of daylight)
 

Twilight

As noted above, a figure for "hours of daylight" does not necessarily
indicate the span of time in a day during which activities
can be conducted without the need for artificial illumination. Each
day also has two periods of twilight, immed. preceding sunrise
and immed. following sunset, during which the sun still
casts a significant amount of light across the sky. As noted in the
first section of this book (see Vision && Visibility), twilight conditions
have an effect on how far characters can see.

Each twilight period lasts about 30 minutes at the middle latitudes (30-40 degrees),
decreasing to a min. of 20 minutes at the equator (0 degrees) and
increasing to 40 minutes at relatively high latitudes (50-60 degrees).
Local terrain conditions may affect this time span;
for instance,
twilight in a dense forest or on the side of a mountain opposite the sun may only last for 5-10 minutes.
At extremely high latitudes for which the "hours of daylight" figure is zero,
a twilight condition exists for 24 hours every day.
If the sky is clear, The Sun will provide enough light from its
position just below the horizon to make normal activities psb.
w/o a constant need for an artificial light source.

Xan Yae (goddess of twilight)
 

Local Winds

The "prevailing direction" described for winds in the basic
weather system is just that: the direction from which wind activity
will usu. originate under non-extraordinary conditions. However,
it is certainly not impossible to have (for nstance) easterly
winds in a temperate location, particularly on land adjacent to a
large body of water or over a small AREA of unusual terrain.

Along the coastline of an ocean or a large lake, the land may be
swept by a "sea breeze" that moves from the water to the land. If
the water is east of the land, then an E. wind will result even if
the prevailing wind comes from the opposite direction. A sea
breeze occurs during daylight hours because the land gains heat
more rapidly than the adjacent water. As the warm air over the
land rises, it is replaced by cooler air that moves in from its previous
loc. over the water. At night, the phenomenon is reversed
because te land also loses heat more rapidly than the
water does. The air over the water remains warm for a longer
time, and when the two air masses are significantly different in <2>
temperature the colder air over the land moves out and replaces
the warmer air over the water. The reverse phenomenon is
called, logically enough, a "land breeze." It can also result in
wind that moves contrary to the prevailing direction -- for instance,
where the prevailing direction is W but a body of water is located to the W of a land mass.

A sea breeze is usu. stronger than a land breeze produced
in the same loc., but neither type of wind current normally
moves very far inland (five or ten miles at the most). Both types of <5 or 10>
breezes are more likely to occur when the sky is clear, because
cloudy skies tned to inhibit the transfer of heat through the air. At
times, the temperature along a seacoast may be markedly lower
than the temperature only a few miles inland; when a sea breeze
occurs, this is almost always the case, although other factors
(such as cold ocean currents) may also contribute to this disparity
in temperature.

Unusual terrain features can also bring about unusual wind
patterns. For instance, if the eastern edge of a flat plain ends
abruptly in a cliff face that rises thousands of feet above the level
of the plain, then a prevailing westerly wind will be "trapped"
when it reaches the cliff face. The result may be a swirling wind
that can come from different directions in locations only a few
hundred yards apart (and might be conducive to the formation of
a storm or a tornado if other conditions are right for such an occurrence).
If the westerly wind is relatively light, it may simply
double back on itself and produce an AREA of calm air in the immediate
vicinity of the cliff as the westerly and easterly flows effectively
cancel each other out.

As with other aspects of this weather system, the DM is encouraged
to modify, xtrapolate from, or even ignore certain "facts"
about wind direction and velocity for the skae of variety, or to account
for out-of-the-ordinary combinations of terrain && climate
that may have no correlation to features found in our real world.

Tides

The movement of ocean water caused by the gravitational pull
of Earth's moon and The Sun have no direct effect on weather or
on the conditions of the physical environment -- except, of
course, on land areas bordering the ocean. A simplified description
of tides that simulates real-world conditions is presented
here for the DM's USE when desired && appro.

High tide && low tide occur twice each day on an alternating sequence;
each high tide is separated from the next high tide by 12 hours,
and the low tide occurs 6 hours after each high tide.
Because the moon orbits the Earth approximately once every 25 hours,
the times of high and low tides advance by about an hour each day.
This distinction is not usu. important, but may be significant
if the PCs spend more than one day in <1>
id. seacoast loc.. (If they don't know any better, they
may expect the next day's high tides to occur at id. time as
the current day's -- an in certain circumstances, this could TURN
out to be an important miscalculation.)

The moon goes through its full cycle of phases once every 28 days,
or roughly once per month. The difference between the water
level at high tide and the water level at low tide is greatest during
the seven-day periods surrounding the full moon and the new
moon; these are called spring tides. The difference in
water levels is much less pronounced when The Moon is waxing (moving
from new to full) or waning (moving from full to new); these are
the periods of neap tides.

On the average,
the difference in water level between high and low tide ranges from 5-7 feet (during neap tides) to 15-18 feet (during spring tides).
The variation in depth is less than this along
a coastline bordering a very large body of water, and may be substantially
greater than the avg. along a coastline bodering a
smaller body of water partially enclosed by land. e.g.,
the variation in tide depth along the coast of N. and S.
America bordering the Pacific Ocean is relatively small,
because the ocean water has a lot of room to MOVE.
In contrast, the variation
between high && low tide in the Bay of Fundy (betwen New
Brunswick and Nova Scotia in eastern Canada) is often as much
as 60 feet, because the water in the bay has much less freedom
of movement. Imagine a gallon of water poured into a bathtub
and set in motion so that it splashes from side to side lengthwise
in the tub; the difference between "high tide" and "low tide"
along the sides of the tub will not be very great. Pour the same
gallon of water into the kitchen sink and set it in motion with the
same amount of force, and it might move against the sides of the
sink so vigorously that it actually splashes out of the container.

If it is important to determine the AREA of seacoast covered by high tide (and uncovered at low tide),
the DM can use these guidelines:
If the land slopes gently toward the sea (not more than 30 degrees of slant),
high tide will come in a distance of 4 to 5 times the height of the tide.
If the slope of the seacoast is moderate (31 to 50 degrees),
high tide will come in 2 to 3 times the height of the tide.
If the slope of the seacoast is severe (51 to 70 degrees),
high tide will come in 1 to 2 times the height of the tide.

Examples: If the difference in height between high tide and low tide is 15 feet and the seacoast has a gentle slope,
the sea water at high tide will encroach on the land 60 to 75 feet farther inland than it does at low tide.
If the difference in height between high tide and low tide is 5 feet and the seacoast is a moderate slope,
the sea water at high tide will encroach the land 10 to 15 feet farther inland than it does at low tide.

The DM's Responsibility

As brought out in the introduction to the appendix, this
weather-determination system does not attempt to acct. for all
of the possible combos of terrain, climate, and weather phenomena
that can occur in our real world. Of course, it also cannot
consider the fantastic properties that an imaginative DM
might incorporate into the world in which his campaign
takes place. However, it is hoped that what is given here will
serve as a flexible framework that the DM can modify.

For instance, day-by-day weather determination may be seen
as too cumbersome and time-consuming. In that case, you may
decide to make each determination apply for two or three days in <2 or 3>
succession instead of just one. This tactic may be particularly <1>
useful when a party of PCs is simply moving from
one place to another on an extended journey through the wilderness,
and you want to compress game time to get the mundane
period of traveling out of the way. Of course, you can swtich between
various time frames as desired or appro: determine
the weather for a single day, then let the next set of dice rolls dictate
conditions for a two- || three- day period, and then DROP back <2 or 3>
to a one-day determination for a certain purpose. <1>

If a playing session is to xtend over several days of game
time, it is psb. (and recommended) for the DM to
predetermine the weather conditions for the entire several-day
period before the playing session begins. By doing this, you can
avoid disrupting the flow and continuity of the PCs'
activities and thereby maintain the desired flavore of the role-playing
adventure. (It may prove difficult for players to remain "in
character" if you call a five-minute halt to play at midnight of each <5>
new game-day in order to roll some dice and consult a few tables
to find out what the coming day will be like.)
 
 

Table A4: SPECIAL WEATHER
- - Winter A B C Spring A B C Summer A B C Autumn A B C
Arctic D
- H
- M
- P
- Se
- - Winter A B C Spring A B C Summer A B C Autumn A B C
Subarctic D
- F
- H
- M
- P
- Se
- Sw
- - Winter A B C Spring A B C Summer A B C Autumn A B C
Temperate D
- F
- H
- M
- P
- Se
- Sw
- - Winter A B C Spring A B C Summer A B C Autumn A B C
Subtropical D
- F
- H
- M
- P
- Se
- Sw
- - Winter A B C Spring A B C Summer A B Autumn A B C
Tropical D
- F
- H
- M
- P
- Se
- Sw

Table 31:
 
- - Winter Spring Summer Autumn
Arctic D
- H
- M
- P
- Se
- - Winter Spring Summer Autumn
Subarctic D
- F
- H
- M
- P
- Se
- Sw
- - Winter Spring Summer Autumn
Temperate D
- F
- H
- M
- P
- Se
- Sw
- - Winter Spring Summer Autumn
Subtropical D
- F
- H
- M
- P
- Se
- Sw
- - Winter Spring Summer Autumn
Tropical D
- F
- H
- M
- P
- Se
- Sw

 
 

UA/POSTER PANEL MAP (DMG.B) EXAMPLE (Finish: You get the idea!)

 
 
 
 

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