Weather

Cyclones, typhoons and hurricanes

What’s the difference between a cyclone, a
typhoon and a hurricane? In fact, there is none.
These are the regional names given to a certain
type of violent storm. So, cyclones occur in the
south Pacifi c and Indian Ocean, typhoons in
the north-west Pacifi c, while in the Atlantic or
north-east Pacifi c they’re called hurricanes.
These violent storms are characterised by
extremely strong winds that can gust in excess
of 200 kilometres (125 miles) per hour,
torrential rain, fl oods and extremely high seas.
At the centre of these storms is an ‘eye’, a
circular region typically between 30 and 65
kilometres (20 and 40 miles) wide that moves
with the storm and marks the low point of the
atmospheric depression. The eye itself is cold,
deceptively calm and sunny, though the
strongest winds and thunderstorms encircle its
border, forming the eyewall.
The ingredients for a storm of this type
include an existing weather system combined
with warm seas, which is why they only ever
occur in subequatorial latitudes. These storms
don’t form within 500 kilometres (300 miles) of
the equator because they rely on the swirling
Coriolis effect for its rotation, which diminishes
to zero the closer you are to the equator. With
rare exceptions, neither do they form in waters
with a surface temperature colder than around
26 degrees Celsius (80 degrees Fahrenheit),
which rules out much of the rest of the world.
As with many types of extreme weather, the
size and intensity don’t necessarily refl ect its
notoriety: the typhoon, for example, is
typically several times bigger than its Atlantic
cousin, the hurricane. But many smaller
hurricanes have achieved a higher profi le
simply because they made landfall and
devastated the highly populated southern
states of the US.

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