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What Are the Causes of Tornadoes and Hurricanes?

Tornadoes and hurricanes are both extreme weather events. They can both cause serious damage to property and loss of life. Hurricanes begin out over the ocean and often move in land. In contrast, tornadoes commonly form over land, however, they can occur over oceans. Each phenomenon is caused by different factors.

Tornadoes
- Tornadoes, or twisters, occur around the world, but are most commonly found in "Tornado Alley" -- a vaguely defined area in the center of the United States . A tornado is a violently rotating funnel of air that reaches down from a thunderstorm to the ground. Initially tornadoes may appear nearly transparent until dust and debris are picked up. The most intense tornadoes have wind speeds of up to 250 miles per hour. Moreover, tornadoes can be up to a mile wide and vary from being almost stationary to moving at 70 miles per hour.
Causes of a Tornado
- Tornadoes originate from severe thunderstorms called supercells, which last longer and are more powerful than a regular thunderstorm. Supercell storms, which produce tornadoes, occur in an unstable atmosphere, when cold dry polar air meets warm moist tropical air. A tornado occurs as wind coming into the storm starts to swirl and forms a funnel. This funnel spins faster and faster, creating a low pressure area that sucks more air into it.
Hurricanes
- A hurricane is a tropical revolving storm. They are also known as tropical cyclones or typhoons. They are intense rotating depressions that generally form over oceans at tropical latitudes. Torrential rainfall, thunder and lightning, and very strong winds are all commonly associated with hurricanes.
Causes of Hurricanes
- Hurricanes often start as a small cloud mass on one side of the equator, developing over warm seas with a temperature of around 80 degrees Fahrenheit. The atmospheric pressure is reduced as moisture and warm air rise, forming a depression. Within this depression, the atmospheric moisture condenses to form thunderclouds. The empty space left by the rising warm air is filled by cold air rushing in. As the earth rotates, this air mass is bent and spirals upwards, promoting the development of swirling winds. These swirling winds gradually increase in speed. Eventually a hurricane develops and begins to move, fueled by a steady flow of warm, moist air. Thus, warm sea surface temperatures in equatorial regions, which promote large masses of rising warm, moist air, are the principal driving force behind hurricanes.

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