Life Cycle
In its early stages, a tropical system appears on the satellite image as a relatively unorganized cluster of thunderstorms. If weather and ocean conditions are favorable, the system can undergo genesis and become a tropical depression (number 1 in the figure). At this point, the storm begins to take on the familiar spiral appearance due to the flow of the winds and the rotation of the earth. Once it moves over land, the storm begins to weaken, although its impacts may continue for days.
Composite imagery of Hurricane Rita from a tropical depression (1), tropical storm (2), hurricane (3), and major hurricane (4 and 5)