Cyclone, hurricane, typhoon: Different names, same phenomenon

They may have different names according to the region they hit, but typhoons, hurricanes and cyclones are all violent tropical storms that can generate 10 times as much energy as the Hiroshima atomic bomb.

Typhoon is the Asian term for a low-pressure system that is called a hurricane in the Atlantic and northeast Pacific and a cyclone in the South Pacific and Indian Ocean.

But meteorologists use the term "tropical cyclone" when talking generally about these immensely powerful natural phenomena, which are divided into five categories according to the maximum sustained wind force and the scale of the potential damage they can inflict.

Typhoon Hagupit, which roared in from the Pacific Ocean and lashed eastern Philippines on Saturday with windgusts of 210 kilometres (130 miles) an hour, is the most powerful storm to hit the Southeast Asian country this year.

Hagupit comes a year after Super Typhoon Haiyan devastated large swathes of the archipelago, claiming more than 7,350 lives.

Every year, some 20 super storms or typhoons hit the Philippines, of the 80 or so that develop above tropical waters annually.

Cyclones are formed from simple thunderstorms at certain times of the year when the sea temperature is more than 26 degrees Celsius (79 Fahrenheit) down to a depth of 60 metres (200 feet).

Sucking up vast quantities of water, they often produce torrential rains and flooding resulting in major loss of life and property damage.

They also trigger large swells that move faster than the cyclone and are sometimes spotted up to 1,000 kilometres ahead of the powerful storm. The sea level can rise several metres.

These powerful weather formations can measure between 500 and 1,000 kilometres in diameter and have a relatively calm "eye" at the centre.

They weaken rapidly when they travel over land or colder ocean waters.

Cyclones are closely monitored by satellites, and specialised centres around the world -- in Miami, Tokyo, Honolulu and New Delhi -- track the super storms` trajectories under the coordination of the World Meteorological Organisation.