Atmosphere Contents

6. Secondary Circulation

From thunderstorms to hurricanes

Thunderstorms

The initial mass of a thunderstorm with only a slight wind disturbance is known as a tropical disturbance. When winds increase to between 10 and 17.5 m/s it becomes known as a tropical depression. When the winds are between 18 and 33 m/s, this becomes known as a tropical storm and may last 4 to 5 days. The storm is classed as a hurricane only when winds exceed 33 m/s, a stage that lasts maybe 2 or 3 days.

When do thunderstorms become classed as hurricanes?