Tropical storm

Tropical storms are exceptionally severe, much worse than a standard thunderstorm. They can cause great damage to property and loss of life, so it is fortunate that they are rare.

Tropical storms can only form in certain parts of the world and under certain climatic conditions. They are classified according to severity - a tropical storm is not as bad as a hurricane, but worse than a tropical depression.

Tropical cyclones are classified into three main groups - tropical depressions, tropical storms, and tropical cyclones/tyhoons/hurricanes (the name of this group varies according to region).

A tropical depression is an organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of less than 17 metres a second (33 knot, 61 km/h or 38 mi/h).
A tropical storm is an organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds between 17 and 33 metres a second (34-63 knot, 63-117 km/h or 39-73 mi/h).
A tropical cyclone/hurricane/typhoon has maximum sustained wind speeds exceeding 33 metres a second.