Slayt 1 - RTC, Regional Training Centre - Turkey

7- Hydrostatic Models Most grid point models and all spectral models in thecurrent operational NWP suites are hydrostatic. That is, theyuse the hydrostatic primitive equations, which assume abalance between the weight of the atmosphere and thevertical pressure gradient force. This means that no verticalaccelerations are calculated explicitly. The hydrostatic assumption is valid for synoptic- andplanetary-scale systems and for some mesoscalephenomena. A most notable exception is deep convection,where buoyancy becomes an important force. Hydrostatic models account for the effects of convectionusing statistical parameterizations approximating the largerscalechanges in temperature and moisture caused by nonhydrostaticprocesses.