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Tropical Storms
Other Names
• Otherwise known as hurricanes, cyclones,
typhoons, and wily willies (the Australian name!).
• These are very intense areas of very low pressure,
approximately 500 to 1000 kilometres in diameter.
• Tropical storms form over water that is above
26.5°C in temperature.
• The warm water heats the air above it, causing it to
rise rapidly.
• Cooler air from elsewhere rapidly moves in to
replace the rising air and the process starts again.
How Do They Occur?
• The rapidly rising moist air, cools as it ascends and forms
tall cumulo-nimbus clouds.
• These slowly spin around the central point.
• Jet streams above the storm clouds continue to suck the
air up.
• Cooling air sinks down through the spiralling mass of
clouds to produce a central eye of the storm.
• Tropical storms move quickly over water, as long as it is
warms enough to keep the storm energised.
• Once over land, where there is less moisture and the
surface is cooler, tropical storms quickly calm down.
Formation
• As the storm approached there would be a drop in
temperature and pressure.
• Wind speeds would begin to increase and clouds
would form.
• As the storm is overhead the pressure would fall
rapidly, as would the temperature.
• Wind speeds would be in excess of 150km/hr and
the rain would be torrential.
• The wind would whip up waves that could swamp
entire coastal areas, or drown entire coral islands in
the Pacific.
Formation
• The eye of the storm is overhead.
• Skies are clear, the temperature and pressure increase, and
the wind dies down.
• Unfortunately this is only a brief lull in the storm.
• The storm hits again.
• Temperature and pressure falls.
• Torrential rain and wind speeds of over 100km/hr occur.
• The winds are now coming form the opposite direction than
they were before.
• After the storm the temperature and pressure rise again.
• The rain becomes showers, and the winds die down.
• The clean up operation begins!