A very simple thermodynamic model of a planet, based on first order approximations of its (black bodies) radiation balance, and includes two radiation modulating effects i.e. albedo and green house as well as two heat stores (ocean and atmosphere). It is a lumped model which does not consider spatial variations and resulting mass transports - thus no heat exchange between e.g. equatorial and polar regions. As a consequence all values are surface specific i.e. per square meter. The radiation balance is in W/m² and the heat reservoirs are in J/m² i.e. water and air columns with a cross section of 1 m².