The exchange of airmass properties and the associated momentum
transports produced on a worldwide scale by the migratory
large-scale disturbances of middle latitudes.
When the atmospheric circulation
is regarded as a large-scale turbulence
process, the cyclones
are considered to be eddies
superposed on the average zonal wind
currents. The mixing length
, that is, the average distance over which these traveling eddies maintain the characteristics of their original environment
, has a value near 108
cm. The coefficient of turbulent mass exchange or the exchange coefficient, which is a measure of the intensity of the large-scale exchange processes and hence of the intensity of the general circulation
, has a magnitude of between 108
(compared with a value of about 102
for small-scale turbulence). On the basis of results obtained so far, there is considerable doubt whether turbulence concepts can be applied meaningfully to the large-scale features of the atmosphere
Haurwitz, B. 1941. Dynamic Meteorology. 265–267.
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