# Burger number

From Glossary of Meteorology

## Burger number

A dimensionless number, Bu, for atmospheric or oceanographic flow expressing the ratio between density stratification in the vertical and the earth's rotation in the horizontal: where

*N*is the Brunt–Väisälä frequency, Ω is the angular rotation rate of the earth,*H*is the scale height of the atmosphere,*L*is a horizontal length scale of typical motions, Ro is the Rossby number, Fr is the Froude number, and*R*_{D}is the Rossby deformation radius.Bu is often of order one for many atmospheric phenomena, meaning that both stratification and rotation play nearly equal roles in governing vertical and other motions in the fluid.

Cushman–Roisin 1994. Introduction to Geophysical Fluid Dynamics. 320 pp.

Copyright 2022 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact permissions@ametsoc.org. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code § 107) or that satisfies the conditions specified in Section 108 of the U.S.Copyright Act (17 USC § 108) does not require AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, require written permission or a license from AMS. Additional details are provided in the AMS Copyright Policy statement.