With the heart of hurricane season upon us, it's a good time to review some common tropical terminology that you'll hear repeatedly in coming weeks.

Budding hurricanes go through several stages of development. A disorganized cluster of tropical thunderstorms is often called a tropical wave or tropical disturbance. If a center of low pressure forms within the cluster and winds reach about 25 mph, the system becomes a tropical depression and is marked on weather maps with an "L." If winds strengthen to 39 mph, the tropical depression graduates to a tropical storm, and that's when it gets a name and a symbol - sort of an open circle with wings. Finally, if winds strengthen to 74 mph, the tropical storm is upgraded to a hurricane, and the open circle is filled in.

As a hurricane, the storm's intensity is rated from 1 to 5 on the Saffir-Simpson scale. This intensity scale was devised in the early 1970s by Herbert Saffir, an engineer, and Robert Simpson, then the director of the National Hurricane Center. They combined structural engineering and meteorology to quantify the level of damage to expect from a hurricane. The rankings are called "categories," and categories 3, 4 and 5 are considered "major" hurricanes.