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0e139b8640
These should probably be overridable per theater and per season, but even with that we'll want some defaults. https://github.com/dcs-liberation/dcs_liberation/issues/2862
77 lines
2.7 KiB
ReStructuredText
77 lines
2.7 KiB
ReStructuredText
#######
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Weather
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#######
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Weather conditions in DCS Liberation are randomly generated at the start of each
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turn. Some of the inputs to that generator (more to come) can be controlled via
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the config files in ``resources/weather``.
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**********
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Archetypes
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**********
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A weather archetype defines the the conditions for a style of weather, such as
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"clear", or "raining". There are currently four archetypes:
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1. clear
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2. cloudy
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3. raining
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4. thunderstorm
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The odds of each archetype appearing in each season are defined in the theater
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yaml files (``resources/theaters/*/info.yaml``).
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.. literalinclude:: ../../resources/weather/archetypes/clear.yaml
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:language: yaml
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:linenos:
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:caption: resources/weather/archetypes/clear.yaml
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Wind speeds
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===========
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DCS missions define wind with a speed and heading at each of three altitudes:
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1. MSL
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2. 2000 meters
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3. 8000 meters
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Blending between each altitude band is done in a manner defined by DCS.
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Liberation randomly generates a direction for the wind at MSL, and each other
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altitude band will have wind within +/- 90 degrees of that heading.
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Wind speeds can be modded by altering the ``speed`` dict in the archetype yaml.
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The only random distribution currently supported is the Weibull distribution, so
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all archetypes currently use:
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.. code:: yaml
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speed:
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weibull:
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...
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The Weibull distribution has two parameters: a shape and a scale.
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The scale is simplest to understand. 63.2% of all outcomes of the distribution
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are below the scale parameter.
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The shape controls where the peak of the distribution is. See the examples in
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the links below for illustrations and guidelines, but generally speaking low
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values (between 1 and 2.6) will cause low speeds to be more common, medium
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values (around 3) will be fairly evenly distributed around the median, and high
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values (greater than 3.7) will cause high speeds to be more common. As wind
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speeds tend to be higher at higher altitudes and fairly slow close to the
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ground, you typically want a low value for MSL, a medium value for 2000m, and a
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high value for 8000m.
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For examples, see https://statisticsbyjim.com/probability/weibull-distribution/.
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To experiment with different inputs, use Wolfram Alpha, e.g.
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https://www.wolframalpha.com/input?i=weibull+distribution+1.5+5.
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When generating wind speeds, each subsequent altitude band will have the lower
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band's speed added to its scale parameter. That is, for the example above, the
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actual scale parameter of ``at_2000m`` will be ``20 + wind speed at MSL``, and
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the scale parameter of ``at_8000m`` will be ``20 + wind speed at 2000m``. This
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is to ensure that a generally windy day (high wind speed at MSL) will create
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similarly high winds at higher altitudes and vice versa.
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