Wind occurs when air moves with respect to the Earth’s surface. Air motion is produced by pressure gradients that are formed when air in one location is heated to a temperature that is warmer than another. Heating creates high pressure in the upper atmosphere, which moves high-level air away from the area of heating. This motion induces low pressure at the surface, pulling surface air toward the area of heating, and forming a convection loop. The Earth’s rotation strongly influences atmospheric circulation through the Coriolis effect. The Coriolis effect causes the apparent deflection of winds relative to the Earth’s surface.