Polar cell

This is a fairly simple circulation system, the driving force of which is the difference in the heating of the earth's surface at the poles and at moderate latitudes. Although around 60 degrees south and north latitude the air is colder and drier than in the tropics, it is still warm enough to form a convection current. Air circulation is limited by the troposphere , i.e. a layer from the surface to a height of about 8 km. Warm air rises at low latitudes and moves to the poles in the upper layers of the troposphere. Reaching the poles, the air cools and falls, forming a zone of high pressure - a polar anticyclone.

Near-surface air moves between the high pressure zone of the polar anticyclone and the low pressure zone of the polar front, deflecting to the west under the influence of the Coriolis force , as a result of which east winds form - east winds of the polar regions surrounding the pole in the form of a vortex form at the surface.

The air stream from the poles forms very long waves - Rossby waves , which play an important role in determining the path of the high-altitude jet stream in the upper part of the Ferrel cell , a circulation cell located at low latitudes.

The polar cell is clearly expressed in winter, when the temperature gradient is greatest, and decreases or even disappears in summer. The Antarctic polar cell as a whole is more distinctly arctic due to the lesser influence of land on the periphery and less pronounced Rossby waves, which affect the destruction of the cell in the Arctic. The sudden destruction of the polar cell is known as “ sudden stratospheric warming, ” in which the upper atmosphere can warm up to 30-50 degrees in a few days.

In general, the Arctic cell is elongated and has two centers - above the Baffin Land (in summer it moves to the Bering Sea ) and over northeastern Siberia , the latter zone is known as the Asian anticyclone . In rare cases, the anticyclone can move much farther south, as happened over North America in 1985 , leading to record low temperatures.

The chemical composition of the polar cells, especially the pronounced Antarctic cell, leads to depletion of ozone in the stratosphere and the formation of ozone holes . Nitric acid in polar nacreous clouds reacts with freons and some other compounds with the formation of chlorine and bromine ions, which catalyze the photochemical destruction of ozone. Such clouds effectively form only under conditions of temperatures up to −80 ° C, which are rarely reached in the Arctic, which explains the smaller scale of ozone depletion in this zone. Chlorine concentrations increase in winter, which is why minimum ozone concentrations are reached in spring, when sunlight returns to the polar regions.

• Ferrel cell
• Hadley Cell
• General atmospheric circulation

• Polar Whirlwind - Dictionary of the Winds