The Ferrel cell is usually shown between the Hadley and Polar cells, e.g. atmospheric circulation. It is named after William Ferrel, who was concerned with describing the surface flow in the Temperate zone of air that came from the Horse Latitudes, namely the Westerlies. In the region of the Atlantic ocean the Westerlies are the northern part of the general circulation of air about the high pressure system that sits over the Horse latitudes. The main 'problem' with the Ferrel cell is that it is thermally indirect. The Hadley cell is a circulation pattern that dominates the tropical atmosphere, with rising motion near the equator, poleward flow 10-15 kilometers above the surface, descending motion in the subtropics, and equatorward flow near the surface. ... Atmospheric circulation is the large-scale movement of air, and the means (together with the ocean circulation, which is smaller [1]) by which heat is distributed on the surface of the Earth. ... William Ferrel This page is about the meteorologist; for the comedian, see Will Ferrell. ... Horse latitudes or Subtropical High are subtropical latitudes between 30 and 35 degrees both north and south, characterized by light winds and hot, dry weather, caused by descending air. ... The westerlies are the prevailing winds in the middle latitudes between 30 and 60 degrees latitude, blowing from the high pressure area in the horse latitudes towards the poles. ...

However, the true atmospheric circulation is rather more complex than the simplified zonal mean pictures would lead one to suspect... It is possible to argue that the Ferrel cell does not exist.

North American westerlies

In general, the surface flow of the Westerlies over the U.S. does not follow the expected flow. In the Temperate latitudes, ground winds are of cyclonic, and anticyclonic, systems which typically have durations of a few days. In the Northern Hemisphere, the high pressure centers of the polar anticyclones are encouraged southward along the east side of the Rocky Mountains, and tend to move slowly southeast. The low pressure centers of the cyclones, particularly from the warm southern waters, move slowly northeast. Their average, and slow as to be imperceptible, westerly component of motion is, as a practical experience, overwhelmed by their strongly felt veering component (the vectors of which statistically add to zero). The resulting flow has no constant direction and is different from that expected over open ocean. This article is about the meteorological phenomenon. ... Insert non-formatted text here The Northern Hemisphere is the half of a planets surface (or celestial sphere) that is north of the equator (the word hemisphere literally means half ball). On the Earth, the Northern Hemisphere contains most of the land and population. ... In meteorology, an anticyclone (i. ... Moraine Lake, and the Valley of the Ten Peaks, Banff National Park, British Columbia, Canada The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. ... Radar image of a tropical cyclone in the northern hemisphere. ...

Jet streams

In the zone of the Westerlies, pressure-driven warm ground-air flowing north is forced to rise over pressure-driven cold ground-air flowing south. The Coriolis effect, causes the north moving air, which is forced to rise at cold and warm fronts, to veer to the right and form westerly jet streams aloft. The flow of air aloft is not acted on by any pressure that could cause it to flow back to the subtropics. But as friction slows its motion, the air aloft above the Polar front can move north to become the downward settling frigid air of the Polar zone. From there it flows outward over the ground as the Polar easterlies. In the inertial frame of reference (upper part of the picture), the black object moves in a straight line. ... Jet streams are fast flowing, relatively narrow air currents found in the atmosphere at around 12 km above the surface of the Earth, just under the tropopause. ... The polar easterlies are the prevailing winds that blow from the high-pressure areas of the polar highs at the north and south poles towards the low-pressure areas of the polar fronts at around 60 degrees latitude (north and south). ...

References

• Laing, David (1991). The Earth System: An Introduction to Earth Science Wm. C. Brown ISBN 0-697-07952-X