Tornadoes, climate change and why Dixie is the new Tornado Alley
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Ernest Agee, Purdue University
(THE CONVERSATION) Several deadly tornado outbreaks, some with dozens of destructive storms, have swept across the South in recent years. We asked tornado scientist Ernest Agee to explain what causes tornadoes and how the center of U.S. tornado activity has shifted eastward from the traditional Tornado Alley in recent years.
What causes tornadoes?
Tornadoes start with thunderstorms. Think of the thunderstorm as the parent of the tornado. When atmospheric conditions favor the development of severe storms, tornadoes can form.
The recipe for a tornado requires a few important ingredients: low-level heat and moisture and cold air aloft, coupled with a favorable wind field that increases in speed with height, as well as changes in the wind direction in the lower levels.
The right combination of heat, moisture and wind can develop rotating thunderstorms capable of spinning off a tornado or a tornado family. Thunderstorms capable of spinning off tornadoes typically develop along and ahead of a frontal boundary – where warm and cold air masses meet – often accompanied above by a strong jet stream.
Why do tornado outbreaks seem to be getting more frequent and intense? Is climate change...