2. An air column of radius 1000 km initially at rest with respect to the surface of the earth at 60N expands to twice its original surface area because of horizontal divergence. What tangential velocity (in km/h) relative to the earth will develop at the periphery of the air column.


Fundamental Relation Needed:  Conservation of Absolute Circulation







Basic Definitions Needed

Definition of circulation


Relation of tangential velocity to angular velocity






where A is the cross-sectional area of air column.