Atmosphere Contents

5. General Circulation

There are weak polar cells at high latitudes

Behind the polar front, the region of low pressure dividing the cold polar and warm tropical air masses, is the polar cell. Here, some of the rising air from the polar front region is deflected nothwards, cools and descends over the pole itself. This forms the upper limb of the Polar cell. This convergence of cold air at the pole then flows southwards back to the polar front region forming the lower limb of the polar cell. While this air is returning to the polar front, the Coriolis force acts on the air mass giving it an easterly flow; hence known as the polar easterlies. The polar cell is theoretically similar to the Hadley cell, having a uniform temperature distribution. However, the cell is not as well developed because of the relative small size of the polar region towards which energy is being transported.

General circulation and the polar cell

Why do weak polar cells form at high latitudes?