Hurricanes originate from warm tropical and sub tropical ocean climates where the water is warm. It is warm in these places all year, but there are slight seasonal changes that contribute to the formation of hurricanes. In the winter season, the days are warm and the nights can be cooler. Because of the cooling temperatures, the ocean water begins to cool as well. In the spring when the temperatures begin to increase, the water temperatures rise, and by summer, create ideal conditions for the formation of hurricanes.
The water cycle and the sun's energy both contribute to the "birth" of a hurricane. Hurricanes form over warm tropical waters. When sea water is at least 80 degrees Fahrenheit and the air is hot and humid it rises into cooler levels of the troposphere. When this occurs, and hot humid air continues to be pumped into the troposphere, tall storm clouds begin to form, the same way they do in a thunderstorms. When the water rises into areas of lower pressure, it condenses and precipitation falls. This is called a tropical disturbance.
Winds are always spinning because of the Coriolis effect. Warm air rises and tries to move to cooler climates which are in the northern hemisphere at the North Pole, and in the southern hemisphere at the South Pole. The winds are deflected by the spinning of the earth on its axis. This causes them to turn to the right or left, depending on the hemisphere. The faster the winds are moving, the faster they spin. This is what causes the spiraling wind patterns in a hurricane.
As the winds pick up speed, the storms begin to come together and spin around an area in the center of the storms. The disturbance begins to turn into a tropical depression. The warm ocean winds spiral upwards in the convection process. As the water vapor condenses into water droplets, energy is released in the form of heat, which boosts the warm rising air and causes the storm to gain strength.
A storm comes to full maturity as a hurricane if the winds reach about 74 miles per hour (Abbott, 2004). When this happens, the winds and clouds begin to spiral faster because of the Coriolis effect; the eye of the storm is formed. The eye is a cylinder at the center of the storm that acts almost like an axis from which the rest of the storm spins. The cool heavy air falls through the cylindrical eye and the warm water vapor and condensed droplets spiral up around the eye. The eye of the storm is calm, because the hurricane is spinning around it with the greatest force happening just along the edge of the eye: the eye wall.
When the hurricane is above water it gains fuel from the moist warm air above the water. The warmer the water is, the larger the storm. The storm slows when it hits land, because there is less water vapor to draw in. Eventually, the storm reaches an area such as land or cooler ocean waters, where it can no longer draw up warm air from the lower levels of the troposphere and the hurricane dissipates.
Storms continue this way until the heat of the summer fades and makes way for winter air that cools the water, usually in November. The cycle begins again in the late spring when the water temperatures begin to rise again.