When Super Typhoon Megi hit the headlines we were asked what is the difference between a typhoon a hurricane and a cyclone.
Because we are often asked about the meaning of Typhoon, Hurricane, Cyclone, Tropical Depression and Tropical Storm we thought we’d re-run this story from last year explaining what they all mean and what are the processes to actually create a tropical storm.
Firstly whether you call it a Typhoon a Hurricane or a Cyclone they are all the same thing – they just form in different parts of the world.
Three Names for the Same Thing
- Tropical Cyclones – form in the Southern Hemisphere (cyclonic)
- Hurricanes – form around America – either in the Atlantic Ocean or in the eastern Pacific Ocean (east of the International Dateline)
- Typhoons form in the western Pacific (west of the International Dateline). This means a Hurricane that moves through the International Dateline would then become a Typhoon.
Another thing all these tropical storms have in common is how they are made…
How a storm is made
- Step 1: A tropical ‘wave’ is needed. This is literally a wave in the air, or a disturbance or the normal easterly flow. The wind tries to move another direction and it causes the air pressure to start falling – and the air to start spinning – creating a low.
- Step 2: This then forms into a tropical depression. It’s given a number. For example, TD2 (for the second Tropical Depression of the official storm season).
- Step 3: Wind speeds start to average gale force – officially making it a Tropical Storm. It’s at this point the storm is named. In our part of the world this would become a Category 1 cyclone.
- Step 4: There are some more technical things that need to go on, but once the winds increase we start stepping up the categories. Different regions use different ways to measure a storm’s strength which is a bit of a pain – but this cyclone season (which starts in November and runs until April) we will use the category system used by the Bureau of Meteorology (BOM) in Australia – who really are the cyclone experts in the South Pacific.
Homepage image / File, Flooding from a typhoon in the Philippines last year / Rew Shearer