What causes hurricanes? There are approximately 100 tropical waves that travel westward from the West Coast of Africa through the Atlantic every year. So, how do these waves become one of the ten or so tropical storms, and hurricanes that occur each season. There are several key factors that come together to develop tropical storms and hurricanes: warm sea surface temperatures, light winds aloft, and rotation or spin. If any one of these factors is unavailable, then the tropical storm or hurricane can weaken or decay.
- Warm sea surface temperatures--This is a key ingredient because it serves as the fuel source for hurricanes. Sea surface, or ocean temperatures need to be at least 80 degrees Fahrenheit (27 degrees Celsius) where the system is located in order for it to develop into a tropical storm or hurricane.
- Light winds aloft--Hurricanes and tropical storms travel east to west so they are supported by an easterly wind flow. They are also vertical systems in that they have thunderstorms that build vertically in the atmosphere. These two conditions make hurricanes quite different from the storms that usually bring us our weather, and make it essential to have light westerly winds aloft so that there is no shearing, or tearing apart of thunderstorms.
- Rotation, or spin--In order for the wave to be considered a depression, storm, or hurricane, it must have some rotation, or spin generated by the winds coming together to form it. Without this ingredient, the wave is just another area of low pressure.