High pressure in the Northern Hemisphere churns air from the northeast toward the equator. On the flip side, air is steered from the southeast by high pressure in the Southern Hemisphere. The winds that move this air toward the equator are also known as "trade winds" and converge in the middle of the tropics. That's where the Intertropical Convergence Zone name comes from.

Here, air and water temperatures are typically in the mid-80s. The warm, moist air is heated further by the blazing tropical sun. Steamy air, coming off the ocean, rises until it hits cooler, drier air aloft, forming clouds and thunderstorms. These gigantic storms contain volatile updrafts and downdrafts that can move at speeds of 100 mph.