What are cyclones, hurricanes and typhoons?

A typhoon expected to cause chaos in Japan this weekend has led to England's tie with France in the Rugby World Cup being cancelled.

Typhoon Hagibis is expected to make landfall in the capital, Tokyo, and other surrounding areas on Saturday, although other matches in the tournament may go ahead.

But what causes a typhoon and how are they different to cyclones and hurricanes?

Dark cloudy sky
When warm ocean air rises it starts to cool and clouds form creating an area of high pressure.

Cyclones, hurricanes and typhoons are all the same kind of storm, one that spins and is fed by warm air.

The scientific name for all of these storms is tropical cyclones.

These storms bring very strong winds and a lot of rain. They form over warm oceans and pick up energy as the warm air picks up water and rises.

When the warm ocean air rises it starts to cool and clouds form. This is called an area of high pressure.

As this air rises, there is a lot less air close to the ocean surface. We call this an area of low pressure. More air then moves in to fill the gap where the low pressure is. This then warms and rises causing a spinning cycle as more air then moves in to full that space. As this warm air continues to rise and cool, more and more clouds form.

What is the difference between the three?

Tropical cyclones are powerful spinning storms. Depending on where in the world they form, they have different names. Tropical cyclones that form in the Caribbean or North American region are known as hurricanes.

Those that form in the Far East, close to places like China and Japan are known as typhoons and those that form in the Indian Ocean are called cyclones.

If a tropical cyclone forms above, or north of the equator, it spins in an anti-clockwise direction. If it forms below, or south of the equator, it spins in a clockwise direction. This is all because of the way the Earth turns on its axis.

Why do they cause such devastation?

Tropical cyclones build in strength as they move over areas of water. They do this because the air above the warm water acts as a ‘fuel’. As it warms and rises it is replaced over and over again by new air. This creates the cycles of the storm and why we see the size of many tropical cyclones grow as they move across warm areas of water.

Typhoon Hato brought Hong Kong to near darkness in 2017.
Typhoon Hato brought Hong Kong to near darkness in 2017.

When these tropical cyclones reach land they often reduce in strength as they are no longer travelling over warm water, so essentially run out of ‘fuel’. They still have the potential to cause a great deal of damage with intense winds and rainfall as they gradually lose their energy.

What about the eye of the storm?

As tropical cyclones are storms that spin, they have a central point. This is called the eye of the storm and is often a very calm space. The air pressure is low here and the storm moves around this point.

How have humans adapted to live in places where they experience cyclones, hurricanes or typhoons?

It can be really hard to predict how strong tropical cyclones will be or exactly where they will hit the land.

Tropical cyclones are grouped by the strength of their winds and these help people living in areas where they are forecast to prepare for the storm in the correct way. They may change the shape and size of their buildings as well as use sirens and news bulletins to alert others when a tropical cyclone is predicted. In some countries, during tropical cyclone season residents are encouraged to keep a rations kit in their home with long life food and drink and a first aid kit.

Meterologists investigating a hurricane.
Meteorologists use satellite imaging and other tools to predict when tropical cyclones will form and the path they will take.

Meteorologists are the people who predict weather trends and patterns. They use satellite imaging and other tools to determine when tropical cyclones will form and the path that they will take.

November to April are well known as being cyclone season in the South Pacific, May until October in the Western Pacific and June to November is hurricane season in the Caribbean and Southern USA.

It can take many months, or even years, to get back to normal after a tropical cyclone and governments often have to spend a lot of money to rebuild homes, roads and things like electricity and water supplies.

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