As the surface air pressure decreases at the center of a low-pressure system, winds become stronger and begin to rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. This process is known as cyclonic circulation. The rising air in the center of the storm causes the air to cool, forming clouds and producing precipitation. As the air rises and cools, the pressure at the surface of the storm decreases even more. This drop in pressure draws in more air, which further increases the wind speeds. This process continues until the pressure in the center of the storm reaches its lowest point.