The adjective "tropical" refers to both the geographic origin of these systems, which form almost exclusively in tropical (
http://en.wikipedia.org/wiki/Tropics) regions of the globe, and their formation in Maritime Tropical air masses (
http://en.wikipedia.org/wiki/Air_mass#Classification). The noun "cyclone" refers to such storms' cyclonic (
http://en.wikipedia.org/wiki/Cyclone) nature, with counterclockwise (
http://en.wikipedia.org/wiki/Clockwise_ ... rclockwise) rotation in the Northern Hemisphere (
http://en.wikipedia.org/wiki/Northern_Hemisphere) and clockwise rotation in the Southern Hemisphere (
http://en.wikipedia.org/wiki/Southern_Hemisphere). Depending on their location and strength, tropical cyclones are referred to by various other names, such as hurricane, typhoon, tropical storm, cyclonic storm, and tropical depression.
River