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Energy Density

A tornado is the most destructive force in nature; that doesn't mean it has the most energy. Thunderstorms which produce tornadoes can have 40,000 times as much energy as a tornado! Tornadoes are so destructive because they have a higher energy density than thunderstorms; the energy is concentrated in a small area while the energy in a thunderstorm is spread-out over a much greater area.

Energy and energy density can be compared to weight and force. Energy density is energy per unit volume and force is weight per unit area. If a 100 pound person in flat shoes stepped on your foot, you'd feel it. If the same person stepped on your foot while wearing very narrow high-heels, you might end up with a broken toe. That's because the person's weight is concentrated in a small area. The same holds with tornadoes. They may not have as much total energy as thunderstorms, but the energy they do have is concentrated in a very small area. So small, in fact, that tornadoes have destroyed houses while not damaging the neighbors.

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