Hurricanes are regions of low air pressure that form over oceans in tropical climate regions. Hurricanes are large storms with revolving winds. They form over the warm waters of the ocean when temperature and pressure difference between the water and clouds is large. The clouds pull the moisture and the air near the surface of the water up, toward the clouds, which produces a column of fast-moving air.
At times, the air in one place is warmer than in another place near it. Warm air is lighter and thinner than cool air. When cool heavier air touches warm air, it presses against it and sets in motion. Some of the warm air moves up and sideways. As the warm air keeps moving up and side and out of the way, the cool air rushes in to take its place. This motion of the air is the wind. Most of the air all over the surface of the earth is rotating.
Hurricanes may have a diameter of 400 to 500 miles (640-800 kilometers). It hit land with great force, bringing huge waves and heavy rain. Many hurricanes cause severe flooding.