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This article is true for version 0.1.9





Af Am Aw BWh BWk BSh BSk Csa Csb Csc Cwa Cwb Cwc Cfa Cfb Cfc Dsa Dsb Dsc Dsd Dwa Dwb Dwc Dwd Dfa Dfb Dfc Dfd ET EF An example map from version 0.1.9

Climate is still in active development, but nearly complete. Everything contained within this article is already complete, but still being tuned.

Climate in SotE is modeled by a simple general circulation model. Weather and climate are fully dynamic and responsive to in-game events. Both are updated every month and are governed by the laws of physics. Air over the planet is divided into a grid of air parcels that define air density, velocity, moisture, rainfall, temperature, and pressure.

Climate classification scheme

The game uses Köppen climate classification directly. Climate zones are determined by numerous, realistic variables which include: seasonal variation in temperature, rainfall, humidity, etc. Alongside this indirect variable that affects a world's climate such as proximity to oceans, wind patterns, elevation, etc are also accounted for. Currently, all of Köppen's climate zones are implemented, however until Ecology is implemented with 0.2 it will not be entirely accurate and some zones may be more common than others.

Technical details

Air is approximated as a moist ideal gas. Each tick, solar irradiance is calculated based on orbital parameters and energy fluxes are exchanged between space and air parcels. For this purpose, air parcels are assumed to be thin black bodies that emit and absorb light based on their albedo and emissivity. The Stefan–Boltzmann law is used to approximate their radiation. Additionally, different air parcels absorb various wavelengths of light with different efficiencies, based on their moisture.

After energy fluxes are exchanged, the simulation calculates water evaporation rates for each air parcel. A custom equation is used for this purpose. The evaporation rate is linearly proportional to temperature, wind velocity, and relative humidity. Saturation vapor pressure (needed to calculate relative humidity) is derived using the Magnus-Tetens formula. Air is then moved around the globe. Coriolis effect and the earth's rotation are both taken into account. Prevailing winds and Hadley circulation are taken into account, which results in desertified areas around mid-latitudes. As water vapor is moved against mountain ranges, it condenses which causes rain shadows.

Alongside this, users are able to influence world climate through several defines which affect the worlds climate as of 0.1.9 An example of one of these is Axial Tilts effect on temperature.

Missing components

Currently, ecology has not been implemented into world generation yet, once this is done the effects of plants/trees on the climate [for example, Transpiration] will be implemented.