Formation of :
(i) Sub- Polar high pressure belt : This zone experiences extreme cold throughout the year. As a result, the air remains chilled under the extreme cold that prevails over the poles, and this contributes to the steady high pressure experienced here. Polar winds blow from the Polar high pressure belts to the sub-polar low pressure belts. They are colder and stronger. They are also called Easterly winds.
(ii) Sub-Polar low pressure belt : As this zone is close to the Pole, the air is colder here. Though the cold air remains close to the Earth, the air is thrown up due to the rotation of the Earth. As a result, low pressure is experienced all along the region.