HURRICANE CENTRAL - The 2011 Hurricane Season is here but do you know why a hurricane forms or what a hurricane is?
A hurricane is defined as an area of low pressure with one big difference: instead of cold air in the center of the system, a hurricane has warm air. It also has a well-defined circulation; in other words, a very noticeable counter-clockwise rotation around its center.
A hurricane first begins as a tropical depression with winds of 38 mph or less. If it becomes more organized and winds reach 39 mph or above, the system is deemed a tropical storm and is named. If wind speeds increase to 74 mph the tropical storm becomes a hurricane.
There are three main ingredients in hurricane formation. The first is very warm ocean water with a temperature of 80 degrees or higher. The second ingredient is moisture; a big, thick layer of moisture extending from sea surface to roughly 20,000 feet. The final ingredient needed for hurricane formation is light, high wind within the atmosphere, otherwise known as low wind shear. This allows the hurricane to grow vertically. When we mix together these elements an area of low pressure is able to form and strengthen creating a hurricane.
To measure the strength of the hurricane we use a scale of intensity called the Saffir-Simpson scale which runs from category one to five, with five being the most powerful with winds of 155 mph or greater.