Use weibull distribution for wind generation.

Wind speeds should not be uniformly distributed. This switches to a
Weibull distribution which allegedly (see the bug) is good enough.
Experimentally that seems true as well, though I know nothing about how
wind works irl. This at least looks like it'll generate reasonable
variation in missions while keeping the 1st through 3rd quartile
behaviors from getting out of hand.

I'm very uncertain about the scaling factor aspect of this. Naively the
wind speeds at different altitudes ought to be somewhat correlated, but
I'm not sure how much, and whether this kind of scaling is at all the
right way to do it. As before, meh, close enough?

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2861.

changelog.md

@@ -12,6 +12,7 @@ Saves from 6.x are not compatible with 7.0.
 * **[Mission Generation]** Units on the front line are now hidden on MFDs.
 * **[Mission Generation]** Preset radio channels will now be configured for both A-10C modules.
 * **[Mission Generation]** The A-10C II now uses separate radios for inter- and intra-flight comms (similar to other modern aircraft).
+* **[Mission Generation]** Wind speeds no longer follow a uniform distribution. Median wind speeds are now much lower and the standard deviation has been reduced considerably at altitude but increased somewhat at MSL.
 * **[Modding]** Updated Community A-4E-C mod version support to 2.1.0 release.
 * **[Modding]** Add support for VSN F-4B and F-4C mod.
 * **[Modding]** Custom factions can now be defined in YAML as well as JSON. JSON support may be removed in the future if having both formats causes confusion.

game/weather.py

@@ -21,6 +21,7 @@ from game.utils import (
     interpolate,
     knots,
     meters,
+    Speed,
 )
 
 if TYPE_CHECKING:
@@ -179,56 +180,39 @@ class Weather:
         raise NotImplementedError
 
     @staticmethod
-    def random_wind(minimum: int, maximum: int) -> WindConditions:
+    def random_wind(
+        weibull_shape: float,
+        weibull_scale_speed: Speed,
+        at_2000m_factor_range: tuple[float, float],
+        at_8000m_factor_range: tuple[float, float],
+    ) -> WindConditions:
+        """Generates random wind."""
         wind_direction = Heading.random()
         wind_direction_2000m = wind_direction + Heading.random(-90, 90)
         wind_direction_8000m = wind_direction + Heading.random(-90, 90)
-        at_0m_factor = 1
-        at_2000m_factor = 3 + random.choice([0, 0, 0, 0, 0, 1, 1])
 
-        high_alt_variation = random.choice(
+        # The first parameter is the scale. 63.2% of all results will fall below that
-            [
+        # value.
-                -3,
+        # https://www.itl.nist.gov/div898/handbook/eda/section3/weibplot.htm
-                -3,
+        msl = random.weibullvariate(
-                -2,
+            weibull_scale_speed.meters_per_second, weibull_shape
-                -2,
-                -2,
-                -2,
-                -2,
-                -2,
-                -1,
-                -1,
-                -1,
-                -1,
-                -1,
-                -1,
-                -1,
-                0,
-                0,
-                0,
-                1,
-                1,
-                2,
-                3,
-            ]
         )
-        at_8000m_factor = at_2000m_factor + 5 + high_alt_variation
+        at_2000m_factor = random.uniform(*at_2000m_factor_range)
-
+        at_8000m_factor = random.uniform(*at_8000m_factor_range)
-        base_wind = random.randint(minimum, maximum)
 
         # DCS is limited to 97 knots wind speed.
         max_supported_wind_speed = knots(97).meters_per_second
 
         return WindConditions(
             # Always some wind to make the smoke move a bit.
-            at_0m=Wind(wind_direction.degrees, max(1, base_wind * at_0m_factor)),
+            at_0m=Wind(wind_direction.degrees, max(1.0, msl)),
             at_2000m=Wind(
                 wind_direction_2000m.degrees,
-                min(max_supported_wind_speed, base_wind * at_2000m_factor),
+                min(max_supported_wind_speed, msl * at_2000m_factor),
             ),
             at_8000m=Wind(
                 wind_direction_8000m.degrees,
-                min(max_supported_wind_speed, base_wind * at_8000m_factor),
+                min(max_supported_wind_speed, msl * at_8000m_factor),
             ),
         )
 
@@ -328,7 +312,7 @@ class ClearSkies(Weather):
         return None
 
     def generate_wind(self) -> WindConditions:
-        return self.random_wind(1, 4)
+        return self.random_wind(1.5, knots(5), (1, 1.8), (1.5, 2.5))
 
 
 class Cloudy(Weather):
@@ -352,7 +336,7 @@ class Cloudy(Weather):
         return None
 
     def generate_wind(self) -> WindConditions:
-        return self.random_wind(2, 4)
+        return self.random_wind(1.6, knots(6.5), (1, 1.8), (1.5, 2.5))
 
 
 class Raining(Weather):
@@ -376,7 +360,7 @@ class Raining(Weather):
         return None
 
     def generate_wind(self) -> WindConditions:
-        return self.random_wind(2, 6)
+        return self.random_wind(2.6, knots(12), (1, 1.7), (2.2, 2.8))
 
 
 class Thunderstorm(Weather):
@@ -401,7 +385,7 @@ class Thunderstorm(Weather):
         )
 
     def generate_wind(self) -> WindConditions:
-        return self.random_wind(2, 8)
+        return self.random_wind(6, knots(20), (1, 2), (2.5, 3.5))
 
 
 @dataclass