Thermotropic model
From Glossary of Meteorology
thermotropic model
A model atmosphere used in numerical forecasting in which the parameters to be forecast are the height of one constant-pressure surface (usually 500 mb) and one temperature (usually the mean temperature between 1000 and 500 mb).
Thus, a surface prognostic chart can also be constructed. The quasigeostrophic approximation is employed and the thermal wind is assumed constant with height.