It is the change in the wind's direction and speed with height. This is a critical factor in determining whether severe thunderstorms will develop.

The rate of change of wind speed or direction, with a given change in height. This is a critical factor in determining whether severe thunderstorms will develop.

The magnitude of wind change with height. Vertical wind shear can weaken or destroy the cyclone by interfering with the organization of deep convection around the cyclone centre.