Secondary circulation

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In fluid dynamics, a secondary circulation is a weak circulation that plays a key maintenance role in sustaining a stronger primary circulation that contains most of the kinetic energy and inertia of a flow [1] . For example, a tropical cyclone's primary winds are tangential (horizontally swirling), but their evolution and maintenance against friction involves an in-up-out flow that is important to its clouds and rain. On a planetary scale, Earth's winds are mostly east-west or zonal, but that flow is maintained against friction by the Coriolis force acting on a small north-south or meridional secondary circulation.

Zonal and meridional

The terms zonal and meridional are used to describe directions on a globe.

Coriolis force A force on objects moving within a reference frame that rotates with respect to an inertial frame.

In physics, the Coriolis force is an inertial or fictitious force that acts on objects that are in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motion of the object. In one with anticlockwise rotation, the force acts to the right. Deflection of an object due to the Coriolis force is called the Coriolis effect. Though recognized previously by others, the mathematical expression for the Coriolis force appeared in an 1835 paper by French scientist Gaspard-Gustave de Coriolis, in connection with the theory of water wheels. Early in the 20th century, the term Coriolis force began to be used in connection with meteorology.



  1. Holton, James R., author. An introduction to dynamic meteorology. ISBN   9780128093290. OCLC   1124306270.CS1 maint: multiple names: authors list (link)

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