Dangerous swirls of hyperactive air—tropical storms—form over oceans and seas around the globe. Depending on where it is, the storm may earn one of several different labels. Hurricane: This is the term generally used in the Western Hemisphere. The name is a blend of Caribbean Indian and Spanish words which mean "evil spirits" and "big wind." Typhoon: Storms that hit China, Japan, or Southeast Asia often get this name. It's a mix of Chinese, Persian, and possibly Greek words. Cyclone: Perhaps rooted in Greek for "the coil of a serpent," this term prevails in India and Bangladesh.

Hurricanes and tornadoes are storms taken to the extreme. Hurricanes and other tropical storms bring some of the scariest experiences nature can dish up: violent winds, torrential rains, huge waves, and flash floods. Tornadoes, or twisters, are swirling, funnel-shaped clouds that darken after hitting the ground. They usually accompany severe thunderstorms.

A tornado looms over Dimmitt, Texas, in June 1995. Source: NOAA Photo Library

Wind speed defines tropical storms. To be considered a hurricane, the storm must create not-so-gentle breezes that sprint along at 118 kilometers (74 miles) an hour. On average, 45 tropical storms reach hurricane strength each year.

The impact of such storms depends a lot on economic conditions in the places where the disaster hits. Affluent
people can afford to build extra strong, wind-resistant buildings—not that they always do. And richer communities have the resources for state-of-the-art weather forecasting and well-organized evacuation plans. Developing countries often lack such benefits—and suffer gravely as a result.

Ten thousand people died when Hurricane Mitch slammed into Central America in the fall of 1998. The strongest Caribbean hurricane in more than a decade, Mitch dumped a year's worth of rain on some areas in a single day. Heavy rains, flooding, and high winds caused landslides. Removal of trees and shrubs for logging and farmland along hillsides had put the land at greater risk for just such damage. BE PREPARED! We can't prevent hurricanes and tornadoes. But some countries—such as Japan, the United States, and Canada—use sophisticated forecasting technology to predict them. Scientists re-create tornadoes and other extreme weather events in labs or on computers in order to study them. Using mobile radar trucks, scientists also chase storms to collect data. Early warnings save lives. Governments develop disaster plans as well as early-warning systems, telling people to evacuate before a serious storm arrives. A tornado "watch" means that conditions are right for one to develop; a tornado "warning" means that one has been sighted or has appeared on radar.

click to enlarge image Hurricane Mitch hits Central America in October 1998. Source: NOAA click to enlarge image The red “hook” in this Oklahoma image could be the birth of a tornado. Source: NOAA Photo Library

How might storms affect our health?