# Quasigeostrophic theory

From AMS Glossary

## quasigeostrophic theory

A theory of atmospheric dynamics that involves the quasigeostrophic approximation in the derivation of the quasigeostrophic equations.

Quasigeostrophic theory is relatively accurate for synoptic-scale atmospheric motions in which the Rossby number is less than unity. However, it cannot accurately describe some atmospheric structures such as fronts or small strong low pressure cells as well as semigeostrophic theory.