Two kinds of storm spin. First, the hurricane. A hurricane is a kind of storm called a tropical cyclone. It forms over tropical or subtropical waters. It needs very warm ocean water, at least 80 degrees Fahrenheit (27 degrees Celsius). Its calm, clear center is called the eye. A ring of thunderstorms called the eyewall surrounds the eye. The winds there are strongest. A storm is called a hurricane when its maximum sustained winds reach 74 miles per hour. North of the Equator, hurricanes spin counterclockwise. South of it, they spin clockwise.

Hurricanes and tornadoes each have a scale. The hurricane scale began as one engineer's idea. Herbert Saffir worked it out while he was working on a report for the United Nations. The Saffir-Simpson scale rates hurricanes from 1 to 5, using only the highest steady wind speed. Tornadoes have their own scale. In 1971, T. Theodore Fujita of the University of Chicago developed a scale to sort tornadoes by their intensity. The Enhanced Fujita scale began operating in the United States in February 2007. Experts do not measure the winds directly. They study the damage a tornado left behind. The wind speeds are estimates based on that damage.

A tornado is a column of air that spins very fast. It reaches from a thunderstorm cloud down to the ground. The funnel you see is made of tiny water droplets. It hangs from the bottom of the storm. A funnel cloud does not touch the ground. If it touches the ground, it is a tornado. A tornado can be only a hundred yards to a few hundred yards across. The average tornado is on the ground for about five minutes. Tornado Alley is a nickname for an area of the central United States. Tornadoes are more common there.

Storms have names, too. Hurricanes, typhoons and cyclones are the same kind of storm. They have different names. Atlantic storm names come from six lists that start over every six years. A committee of the World Meteorological Organization keeps them. In 1979, men's names were added, alternating with women's names.

Forecasters watch storms in several ways. Satellites that circle the Earth watch tropical cyclones from the time they start until they fade. As of November 2026, NOAA Hurricane Hunter crews fly airplanes into storms, even through the eyewall. They gather information for forecasters. The planes drop small probes called dropwindsondes. The probes send back pressure, humidity, temperature and wind readings. For tornadoes, forecasters use Doppler radar. It shows a strongly rotating column of air inside a storm.

A tornado watch means tornadoes are possible in and near an area. A tornado warning means a tornado has been seen or shown by radar. People in the area should go to shelter right away. In a warning, a family goes to a basement or an inside room with no windows. Big open rooms such as gyms are not the best places. When a hurricane is coming, listen to the grown-ups and officials in charge. A family may not be told to leave. Then a safe place is a small inside room, closet or hallway on the lowest level.

Words to know

• tropical: near the Equator
• eyewall: storm ring
• intensity: strength
• typhoons: Pacific hurricanes
• probes: small tools
• radar: storm-seeing tool