If you enable seasons and select a certain one, it will adjust the temperature range and therefore the
climate, vegetation, desert, polar ice caps, and mountain peaks over the whole map. Seasons will always
refer to the season of the northern hemisphere (upper half of the map):
Spring - slightly warmer in northern latitudes, slightly cooler in southern latitudes
Summer - much warmer in northern latitudes, much colder in southern latitudes
Fall - slightly cooler in northern latitudes, slightly warmer in southern latitudes
Winter - much colder in northern latitudes, much warmer in southern latitudes
In addition to the 4 main seasons, there are 4 'half-seasons' in between.
You will definitely notice 'polar icecap creep' and movement of desert areas when you utilize seasons.
The "Temp Swing" variable is used to determine the maximum addition or subtraction to the base temperature
for a season. The range from +value to -value is divided into 8 equal values for each season and half-season
to be added or subtracted to that map tile's base temperature for climate/vegetation coloring.