Dynamic Weather Mod

0.11.3

TWO EUROPEAN CLIMATES

The climate table has two climates of the European continent. A world picks one
up on its own, with no key set and no change to this mod, when it publishes a
latitude and a longitude inside the box.


THE TWO CLIMATES

  western-europe    47.5 to 53.5 N, 0.5 to 8.5 E
      The West European plain from the Paris basin to the Rhine. Maritime: a
      January day mean of 3.0 C and a July day mean of 18.6 C, rain in each
      season, a light wind, and a narrow winter dew point spread that makes fog.

  eastern-europe    50 to 57.5 N, 21 to 36 E
      The East European plain from eastern Poland to western Russia.
      Continental: a January day mean of -5.5 C and a July day mean of 19.5 C,
      the widest day-to-night swing of the table, a dry cold winter, a summer of
      heat cells, and few frontal storms.

WHAT A WORLD NEEDS TO PICK ONE UP

  1. It publishes coordinates. The climate is keyed on the latitude and the
     longitude of the weather manager of the world. A world that publishes
     nothing answers 0.0 and 0.0, which is the Gulf of Guinea and is in no box.

  2. The point is inside the box above.

  3. The climate key is "auto", which is the default. A climate id in the
     configuration overrules the coordinates.

The mod reads the pair one time, about three seconds after the world is up, and
never again in the session. The CLIMATE boot line states what it read and what
that selected:

  CLIMATE boot | world 'Livonia' lat 52.100 lon 21.000 | resolved
  'eastern-europe' (Dfb, Temperate continental / hemiboreal, Eastern Europe) |
  source: coordinate box

"source: coordinate box" is the line that says a box selected the climate. A
server that wants one of the two on a world outside the box sets climate to
"western-europe" or "eastern-europe", and the same line then says
"source: config key 'climate'".

Enjoy the european weather :-)

0.11.2

Bugfix-Release: We measure the difference between our own clock and the world's, age everything it counts in game hours by that difference.

Rain under a blue sky should no longer happen.

0.11.1

0.11.0

KOLGUJEV GETS ITS OWN CLIMATE ZONE

Kolgujev ran the climate of a place 520 km to the south. It has a climate of
its own now: cold, wet, near-permanently windy, and the first vanilla world of
this mod on which it snows.

A climate can also name skies of its own, so the island looks like the island
and not like Everon.


THE GAP

Kolgujev is at 52.372 N, 24.024 W. The north-atlantic box starts at 40 N, thus
the island sat inside it and ran the weather of the open ocean at 47 N.

                    It gave        Kolgujev asks for
  Winter day        10.0 C         2 to 5 C
  Winter night       6.6 C         -2 to 2 C
  Summer day        17.6 C         11 to 14 C
  Sea in winter     11.6 C         6 C


THE THIRD CLIMATE

subpolar-oceanic, 51 to 54 N and -26 to -22. The box contains Kolgujev and no
other world. Everon and Arland were both measured in the game and both are more
than 3.3 degrees south of it.

On the midpoints of the seasons, under a light cloud cover:

  Winter    day  2.9 C    night -0.1 C    sea  5.9 C
  Spring    day  7.7 C    night  3.9 C    sea  9.0 C
  Summer    day 12.4 C    night  8.0 C    sea 12.1 C
  Autumn    day  7.7 C    night  3.9 C    sea  9.0 C

The wind does not stop here. The whole ladder is raised by 1.45 and the winter
by a further 1.35, so a winter rain slot reaches Beaufort 11 and a storm
reaches Beaufort 12 - with no lightning in either, for the reason v0.10.0
gives: a gale is not a thunderstorm.


FOR SERVER ADMINS

No new key. climate accepts a third id, "subpolar-oceanic", and it forces that
climate on any world.

0.10.0

EVERY WEATHER IS BASED ON REALITY

The mod had one climate and it was a Central European one. It has two now, and
it selects between them with the latitude and the longitude that the world
itself publishes.

The vanilla worlds sit in the middle of the North Atlantic. They now get the
weather of that place.

WHAT THE NORTH ATLANTIC GIVES

On the four midpoints of the seasons, under a light cloud cover:

  Winter    day 10.0 C    night  6.6 C    sea 11.7 C
  Spring    day 13.4 C    night  9.7 C    sea 12.4 C
  Summer    day 17.6 C    night 13.4 C    sea 16.2 C
  Autumn    day 14.1 C    night 10.2 C    sea 15.5 C

The daily swing is 3.4 K, against the 6 to 11 K of a continent. A sea does not
let the air move far in one day.

A GALE IS NOT A THUNDERSTORM

There is no land friction within 1,400 km, thus each wind above that ocean is
stronger than the same pattern above land. The whole ladder is raised, and a
winter rain slot reaches Beaufort 10 with no lightning in it.

The daily wind cycle goes the other way. It is a land effect, because the sun
mixes momentum down to the surface through the afternoon, and there is no such
cycle above an ocean.


SEA FOG

Radiation fog needs a clear and calm night. Steam fog needs water that is 8 K
warmer than the air. Neither of them is the fog of an ocean.

Advection fog is the third mechanism and it is the only one that forms in
daylight and in a wind. Warm wet air moves over colder water, and the water
cools the air to its dew point. The sun does not clear it: sea fog holds
through the middle of the day and it ends when the wind changes.

Only a climate that declares it can make advection fog. A continent has no sea
for the air to move over.


WHAT THIS CLIMATE CANNOT SHOW

It does not snow in the middle of the North Atlantic at 47 N. It does not
thunder above a 16 C sea. Sea smoke needs very cold continental air and there
is no continent near enough to make it.

To get the snow of v0.9.0 back, set climateMeanC to 4.0, or set climate to
"continental-temperate". Both are one line of the configuration file.


FOR SERVER ADMINS

One new key in config.json:
  climate - "auto" by default. It selects the climate from the coordinates of
  the world. A climate id forces that climate whatever the world reports. A
  name this build does not know gives one warning and runs on "auto".

0.9.1

fixing wrong cloud settings on the rainy state.

0.9.0

Below freezing, rain now falls as snow.

The mod always knew the temperature and the dew point. It drew the same rain
whatever the two of them said, so a January weather period at -6 C and a July one
at +19 C looked the same from the ground. The weather report already knew better:
it printed SN over that rain. The mod described snow and drew water.

A mood can now show a different SKY when the conditions ask for it. The mood
itself does not change - no weather is more or less likely than it was in v0.8.0,
and the walk from one sky to the next is the walk you already have.


THE SNOW IS RAIN THAT IS TUNED TO READ AS SNOW

Be clear about what this is. The engine has no snow. It has rain, fog and
lightning, and there is no fourth kind of weather to ask for. What the mod ships
is a snow STATE: a deck, a fall and a visibility that are tuned until they read
as snow at the distance you look.

That has limits and they are worth knowing:

- The ground does not turn white. There is no snow cover and no footprints. What
  the engine gives is water. The mod does stop filling the puddles and the cracks
  while snow falls, so the ground no longer looks rain-soaked under a snow sky.
- Walk up to a surface and you will see rain behave as rain.

0.8.0

THE RAIN THAT COOLS THE AIR

Rain that falls through dry air evaporates, and evaporation takes heat out of the air. It is the reason a wet finger held up in the wind feels colder than a dry one.

The air now goes down while rain falls through it, in every season. How far it
goes down is how far the air is from its dew point:

- Dry air cools much. A summer afternoon at 26 C with a dew point of 15 C goes
  down approximately 2 K.
- Moist air cools almost none. A summer night, where the air is already close to
  the dew point, goes down approximately 0.4 K.
- Saturated air cools nothing at all. Autumn and winter air after rain is already
  at its dew point, thus the term gives exactly zero. It stops itself, because
  saturated air stops evaporation.

Do not expect to feel a different sky. This is the temperature number becoming
right, and not the weather becoming dramatic. The place you will see it is a
summer afternoon that a rain band walks across.

0.7.3

Slower drying time after rainfall.

0.7.2

disabled ForceTemperatureTableRecompute()

0.7.1

Your feedback is highly appreciated. Leave a like if you think this mod enhances your games.

Lets discuss on discord about things you would love to see: https://discord.gg/Cn9hAy2xj

0.7.0

THE STORM OUT OF A CLEAR SKY

The five existing moods of the weather (clear, cloudy, overcast, rainy, stormy) 
were a line in the previous versions of this mod, and each change moved one 
step along it. They are a graph now.

The line meant that the sky had to climb through every mood between where it was
and where it went. A storm out of a clear sky was not rare, it was impossible.
Rain always came first. The way down was the mirror of the way up, thus rain
always had to pass through an overcast sky to reach a cloudy one.

Both of those are corrected, and a third fault with them: the mod carries a
"squall" arrival that is approximately twice as fast as an ordinary one, and its
test asked for more wind than a storm has produced for several versions. No storm
in the mod had a quick onset. They do now.


THE HEAT CELL

A short and violent thunderstorm that breaks out of a clear or a cloudy
afternoon, and leaves the air markedly colder behind it.

It is available between 13:00 and 20:00, in the months 4 to 8, and only when the
air is near the top of what the climate of your world delivers. It arrives in 2
to 5 minutes, it continues for approximately 20 minutes, and it always ends in a
cloudy sky. It comes to approximately one summer day in three.


THE FRONT PASSAGE

Rain goes directly to a cloudy sky. This is what a cold front does: the rain
stops, and the sky opens much more quickly than it closed.

0.6.3

THE GAME MASTER'S RE-ROLL

A game master who does not like the weather can now ask for another one.

Move the world date, or turn Automate off and then on. The mod draws a new
weather state and plans the queue again. The draw reads the whole ladder, thus
a re-roll can give any state and not only the neighbour of the state that runs.
A game master on Clear can get a Thunderstorm from one re-roll.

The sky travels to the new weather. It does not jump to it. The wind, the fog
and the rain all ramp, and the rain waits for the cloud deck as usual.

These do not draw new weather:

- The game midnight.
- A change of the time of day. A night operation at 22:00 keeps its sky.
- A repair. When the mod corrects its own queue, the weather stays.

A drag of the date slider across many days gives one re-roll, two seconds after
the slider stops.

New config key: rerollOnGameMasterInput, default true. Set it to false to stop
the draw. The temperature, the sun times and the fog continue to follow the date.

FOR SERVERS AT 1x

The engine cannot make a weather node shorter than 20 real minutes on a world
with a 24 hour day, and a re-roll holds the sky for 10 real minutes more before
it starts to move. Speed the Cycle Duration of the world up if you want the
weather to answer more quickly.

0.6.1

0.6.0 - The fog follows the game master
Steam fog was tested one time, at boot. A game master who moved the world
clock to a calm autumn morning got the morning and no fog.
- The mod asks the question again each time the date or the time of day
  moves, and each time the automation comes back on.
- The fog arrives at once. It does not build over the next forty minutes.
- One drag of the slider gives one decision. A game midnight is not a clock
  change, and neither is a change of the time acceleration.
- The air temperature and the spread are repaired before the mod asks. A
  bank that is on screen is aged through a forward jump.
- A resume drops the fog event, because the mod cannot say what occurred to
  the sky while it was off.
For admins
- bootSteamFogChance is now steamFogSeedChance. The old key still works.
- A refusal is an ordinary log line and no longer a debug line. It names all
  four tests and the value of each one, thus "I moved the clock to a dawn
  and got no fog" has an answer in the log.

Steam fog needs cold air over water that still holds the heat of the summer.
The season for it is the middle of October to November.

0.6.1 - A weather state of the mod's own for the rain
The Rainy rung, which the Thunderstorm rung also maps onto, used the state
of the game. It has a state in the mod's own state machine from this
version, beside the Clear state that v0.5.3 added.
A session still starts in Clear with the Cirrus variant. No script changes.

0.5.4

add missing WeatherState.conf overwrites for early morning steam fog (Autumn/Winter only)

0.5.3

The autumn morning starts in the fog

A session that starts on a calm autumn morning now starts IN steam fog. Before
this release the fog model looked for its events on a check cadence, so the first
fog came long after the first players joined, and a perfect fog morning showed no
fog at all.
- The mod tests the conditions one time at boot: the water more than 8 K above the
  air, the wind below 3.5 m/s, no rain, and the hour near sunrise.
- When they agree, the fog is on screen at the first frame, as a shallow ground
  layer under the sky the session chose.
- It is an ordinary fog event: the same density, and the sun burns it off in front
  of the players.
- It holds at least ten real minutes (depends on your set baseDuration!), so the players who join at the start see it.
- This occurs one time in a session. The fog model then continues as before.

For admins: one new key, bootSteamFogChance, default 1.00. Set it to 0.0 to turn
the seed off. The boot log states the key at every start, and gives one line when
the fog is seeded and a debug line that names all four tests when it is not.

0.5.2

The session starts in real weather

The mod chooses the weather for each session at boot. This release makes that choice correct, and puts the sky in it immediately.

The season controls the choice. In autumn and winter, a storm at boot is now rare.
A session can start to get better. Before this release, the weather at boot always got worse.
The sky is in the chosen weather when the server opens. You do not wait for it.

For admins: do nothing. No configuration key changes, and there is no new key.

0.5.0

The mod now posts a weather report to chat each time it plans new weather — about every 40 minutes on the default settings.

"ARWS 091756Z 25015G22MPS 1600 +RA OVC008 05/01 BECMG 25007MPS 9999 NSW BKN012"

It's a METAR, the real format pilots read. Left to right: time, wind, how far you can see, what's falling, cloud, temperature — and then the forecast. The mod can forecast because it decides the next weather before the sky plays it.

You don't need to learn it. A + means heavy, a G means dangerous gusts, and NOSIG means nothing is coming. That's enough.

The rest, if you want it:
25015G22MPS — wind from 250°, 15 m/s, gusting 22
1600 — you can see 1600 m. 9999 is 10 km or more
+RA heavy rain · -RA light · TS thunderstorm · BR mist · FG fog
05/01 — 5 °C, dew point 1 °C. Close together means fog is likely
BECMG a lasting change · TEMPO a passing one · NSW the weather stops

So the example says: heavy rain, 1.6 km visibility, gusting 22 — and it's clearing to a 10 km view with the rain stopping.

Thunderstorms are less absurd. The report exposed storms hitting 31 m/s sustained with 49 m/s gusts — hurricane force. Now roughly 23 gusting to 36. Still a severe storm; no longer a natural disaster.

The distances are honest. Early builds reported 1900 m in a downpour where you could barely see 1000. The report now reads the same value the game uses to thicken the air, so what it says is what you get.

The report is grey, not the red the game uses for warnings. Server admins can turn it off with metarEnabled = false.

0.4.1

No more wet roads and puddles under a clear, dry sky.

The game draws falling rain only above a certain intensity, but it wets the
ground at any intensity above zero — and there is one value controlling both.
Light rain therefore soaked the world while the sky above stayed visibly dry.
An overcast drizzle would darken every road on the map without a drop falling.
The mod now simply does not ask for rain the game will not draw. Below the
threshold it sends none at all, so a light drizzle slot stays properly dry
instead of looking like the aftermath of a storm nobody saw.

What you will notice:
- Overcast slots no longer wet the ground. They stay grey and dry.
- Rain in a rainy slot starts a little later than before, and arrives as a
  visible shower rather than creeping in invisibly.
- Heavy rain and thunderstorms are unchanged.

For server admins: the threshold is a new config.json key, rainVisibleMin,
default 0.50. Set it to 0.0 to switch the whole thing off and get the old
behaviour back. The exact point where the game starts drawing rain is not
documented anywhere, so 0.50 is a careful estimate for now — if rain looks
like it starts too abruptly or too late on your server, this is the dial.
Nothing else in the weather model changed. Seasons, temperature, fog, wind
and the Game Master handover all behave exactly as they did in v0.4.0.

0.4.0

Game master handover

Game Master > Weather > Automate now switches the mod on and off.
Automate OFF - the mod releases the weather completely. Rain, fog and wind
return to the engine's values within half a second, lightning stops, and the
weather panel works normally: pick a state and it stays.

Automate ON - the mod picks up from the sky you leave it with and plans forward
from there. It re-reads the date, so a season change you made while in control
is carried over. It does not restore the weather from before.

Picking a weather state without touching Automate is now honoured too: the mod
continues from your choice instead of planning straight past it.

Fixes the reason this was needed. Setting the weather by hand used to change
only the sky, while the mod kept writing its own rain, fog and wind on top - a
cloudy sky with a thunderstorm's rain and lightning underneath it, for the rest of the session.

Server admins: no config changes. The routine per-tick log lines are off by default now.

0.2.5

The world's date now drives the weather. Set it in the Weather Editor or from the GM tools; everything below follows from it.

-- What you'll notice --
Seasons. Autumn and winter run grey, windy and foggy. Summer runs clearer, with heavier but shorter rain. Spring is showery, autumn is misty — the two behave differently even though the calendar sits between them.
Temperature is simulated and driven per day, from latitude and season. It's a real band, not a number: clear nights get properly cold, overcast nights don't. This is what thermal optics read — a cold winter night makes bodies and engines pop, a hot afternoon washes TI out.

Fog forms for a reason now. It's driven by how close the air is to its dew point, not a fixed clock. Expect fog on calm clear autumn nights, fog after rain, fog over water on cold mornings — and almost none in July. It burns off with the sun rather than at a set time, and in deep winter it can sit all day.

Summer afternoon thunderstorms fire between 13:00 and 20:00 once the day has heated, hit hard, and leave the air 5–14 °C colder behind them, with a wind shift ahead of the rain.
Fixed: rain no longer cuts off abruptly when the weather clears. It now fades out with the cloud deck.
For Game Masters

The date is the dial. Change it mid-session and temperature and fog respond immediately; the sky's character follows within one weather slot rather than teleporting. The boot log states the date, season and sunrise/sunset it resolved, so you can confirm your choice landed.

-- For server owners -- 

Six new optional keys in $profile:DynamicWeather/config.json, all safe to omit:

Key					Default	
seasonDayOfYearOverride			-1 (off)	Pin the season to a day 1–366, ignoring the scenario date
climateMeanC / climateAmplitudeC			from latitude	Override the climate outright
temperatureOverrideEnabled		true		Turn off the temperature sim, keep the rest
seasonalPatternsEnabled			true		Turn off the seasonal bias, keep temperature and fog
fogModel				"temperature"	"legacy" restores the old fog behaviour

Check your Cycle Duration. Summer storms need the weather to climb the ladder inside one afternoon, and that depends on Cycle Duration and baseDurationMinutes together. The boot log now prints a Convective budget line and warns if storms are unreachable on your settings. At Cycle Duration 3600, use baseDurationMinutes around 4.0; at 21600, 7.0 is comfortable.

-- Known limitations --
No snow or ice. The base game doesn't render them — a −8 °C rainy slot still falls as rain.
Whether the temperature reaches clients (not just the host) is undocumented by the engine and unverified. The weather and fog are correct either way; only thermal optics would be affected.
The cold pool has not yet been observed end-to-end in a live session — the mechanism is in and instrumented, but the 5–14 °C drop and the evening mist behind it are still unconfirmed.

0.2.4

0.2.3

0.2.2

Added discord link

0.2.1

fixed an issue when time of day or acceleration changes in GameMaster

0.2.0

Replace manual weather slot execution by enfusions internal state management.

0.1.1

Added intermediate weather states to overcome flashing state changes

0.1.0

0.0.10

0.0.9