|Physical key figure|
|Named after||Carl-Gustaf Rossby|
|scope of application||geophysics|
The Rossby number (after Carl-Gustaf Rossby ; not ) is a dimensionless number that is mainly used in geophysics for oceanographic and atmospheric phenomena. It can be used to assess the influence of the Coriolis effect on a rotating movement. The Rossby number describes the ratio of inertial force to Coriolis force :
It is defined as:
in dependence of
- the characteristic speed
- the characteristic length over which the observed phenomenon takes place on the earth's surface
- the Coriolis parameter ,
where is the latitude.
Depending on the phenomenon under consideration, the Rossby number can differ by several orders of magnitude. A small Rossby number means that the Coriolis force has a large influence on the system under consideration, while other forces predominate when the value is larger. For example, the value of the Rossby number in tornadoes is large (≈ 10 3 ), in low pressure areas it is small (≈ 0.1 to 1). The earth's rotation can be neglected for large Rossby numbers ( ).
- Helmut Kraus: The Rossby number similarity . In: Ders .: Basics of boundary layer meteorology. Introduction to the physics of the atmospheric boundary layer and micrometeorology . Springer, Berlin 2008, ISBN 978-3-540-75980-5 , pp. 97-102.
- Horst Kurz: Turbulent diffusion in an atmospheric boundary layer with a Rossby number similarity . Dissertation, Technical University Darmstadt 1978.