CONCEPTS in Action
Hurricanes
A hurricane is a huge column of spiraling air with winds blowing at speeds of at least 119 kilometers per hour. Hurricanes are highly destructive if they reach land.
All hurricanes start as storms over warm tropical seas where the water temperature is at least 27°C. As the sun heats the ocean's surface, masses of moist, warm air accumulate and rise up, forming huge clouds. More air is sucked into the region from all directions and spirals toward the center. As the hurricane grows stronger, it moves westward, pushed by prevailing winds. Eventually, hurricanes in the Northern Hemisphere move northward, where the cooler temperatures reduce the supply of warm air and moisture needed to maintain the storm. If the hurricane hits land, it is no longer fed by heat and moisture from the ocean, so it loses energy and dissipates.
Life of a Hurricane
These satellite images show hurricanes at four stages of development.
The hurricane begins as a swirling cloud of rising air.
By day 3, the storm has developed an eye, which is a sign that the hurricane has strengthened.
Within 6 days the hurricane has reached its greatest intensity.
As the hurricane reaches land, it begins to weaken.
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