Structure and features of tropical storms

  • From space, a tropical storm looks like a huge whirlpool of spinning clouds.
  • Tropical storms are enormous, measuring up to 644 kilometres wide and up to 8 km high. They move quickly in the atmosphere, at up to 60 km/h.
  • Tropical storms have circulating winds because of the Coriolis force, caused by the spinning of the planet.
  • The area in the middle of a tropical storm is the eye. The eye is up to 48 km across. It is an area of very light wind speeds and no rain, because the air here is descending.

Huge cumulonimbus clouds surround the eye, creating the eye wall. Here warm moist air condenses as it rises and this gives the characteristic heavy rainfall and high wind speeds.

Tropical storms have air spinning due to the Coriolis force. The eye in the centre is formed by spiralling currents of rising warm air, with cold air sinking in the middle.Tropical storm cross-section

How tropical storms develop

Tropical storms usually form between 5° and 30° latitude.

  • When the ocean surface waters reaches at least 27°C due to solar heating, the warm air above the water rises quickly, causing an area of very low pressure.
  • As the air rises quickly more warm moist air is drawn upwards from above the ocean creating strong winds.
  • The rising warm air spirals upward and cools. The water vapour it carries condenses and forms cumulonimbus clouds.
  • These cumulonimbus clouds form the eye wall of the storm.
curriculum-key-fact
When tropical storms reach a land surface, they begin to lose their energy and die out. This is because they are no longer receiving heat energy and moisture from the ocean, which is needed to drive them.