Question

The air at the sub polar region gets _______.

Answer 1

Lighter

The Polar winds lowering down from Poles towards the Sub Polar region undergo Expansion i.e. if we move towards the Equator from the Poles, we encounter that the Poles having lesser area than Sub Polar regions due to the Geoid shape of Earth, hence, the air descending down from Poles towards SubPolar region undergoes expansion and becomes lighter.