What is needed to create a hurricane?
Hurricanes need four conditions to form:
- low air pressure.
- warm temperatures.
- moist ocean air.
- tropical winds (near the equator).
Once formed, hurricanes take energy from the warm ocean water to become stronger. A storm will strengthen if there is a supply of warm, moist air to feed it. Warm, moist air is found above warm, tropical ocean waters. While a hurricane is over warm water it will continue to grow.
- Winds, many times in the development stages of a tropical system, are below 30 miles per hour. Michael Wyllie: Hurricanes gain in strength when they go over areas of warm water and low sheer in the upper atmosphere. Just the right types of conditions with warm water and weak wind shear allow them to strengthen.
- It was so destructive primarily because levees around New Orleans, Louisiana failed. Levees are water barriers built to prevent flooding (parts of New Orleans have an elevation that is lower than sea level). Very heavy winds also contributed to the damage, but flooding was the most destructive aspect of the hurricane.
- Only tropical cyclones that form over the Atlantic Ocean or eastern Pacific Ocean are called "hurricanes." Whatever they are called, tropical cyclones all form the same way. Tropical cyclones are like giant engines that use warm, moist air as fuel. That is why they form only over warm ocean waters near the equator.
Water vapor is the "fuel" for the hurricanes because it releases the "latent heat of condensation" when it condenses to form clouds and rain, warming the surrounding air. (This heat energy was absorbed by the water vapor when it was evaporated from the warm ocean surface, cooling the ocean in the process.)
- Hurricanes form over the warm ocean water of the tropics. When warm moist air over the water rises, it is replaced by cooler air. The cooler air will then warm and start to rise. If there is enough warm water, the cycle will continue and the storm clouds and wind speeds will grow causing a hurricane to form.
- Katrina formed from the interaction of a tropical wave and the remnants of a previous tropical depression. August 23, 2005 Tropical Depression Twelve formed. The depression became Katrina August 24 when it was located over the Bahamas. Katrina was the 11th tropical storm of the 2005 hurricane season.
- Tropical cyclones extract heat from the ocean and grow by releasing that heat in the atmosphere near the storm center. Sandy started out as a classic hurricane, getting energy from the warm waters of the Caribbean and moving northward along the Gulf Stream.
Updated: 2nd November 2019