Cumulative hurricane tracks around the world from 1950_2005. Hurricanes, or tropical cyclones, occur in two bands around the world, either side of the equator. The bands are a product of the conditions necessary for cyclone formation, that is, a sea surface temperature high enough to drive the required evaporation of sea water, and a distance far enough from the equator so that the Coriolis effect is strong enough to impart a circular motion to the system.