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Poleward movement of fluid can is observed the following plot of zonally averaged Meridional Wind Flow. Note the surface divergence at 30 N and 30 S, where sinking air at the edge of the Hadley circulation encounters Earth’s surface.
(Climatological plot of January July 1948 to 2013)
(Climatological plot of July January 1948 to 2013)
In July, the surface divergence at 30N becomes significantly weaker. The divergence at 30S appears to significantly stronger.
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In the midlatitudes, atmospheric circulation is greatly influence by the earths earth's rotation. In this regime, the Rossby number his is higher (relative to the Rossby number at the equator). The primary method of heat transport in this regime are eddies. These eddies make up what are known as mid-latitude weather systems. Below is a water vapor satellite image of the north pole on May 23, 2014 (found at http://climate.cod.edu/flanis/satellite/polar/index.php?type=polar-wv-48). The swirling eddies can very easily be made out.
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