A stormy region in the tropics more intense than a tropical disturbance but less intense than a tropical storm. Wind speeds in a tropical depression are less than 39 mph.
Tropical cyclone with some rotary circulation at the water surface. With maximum sustained wind speeds of up to 39 miles per hour, it is the second phase in the development of a hurricane.
A tropical storm with winds reaching up to 61 km per hour; such storms develop from tropical disturbances, and may grow to become hurricanes.