About Tropical Cyclones

Oceans and seas have great influence on the weather of continental masses. A large portion of the solar energy reaching the sea-surface is expended in the process of evaporation. These water evaporated from the sea/ocean is carried up into the atmosphere and condenses, forming clouds from which all forms of precipitation result. Sometimes, intense cyclonic circulations occur which is what we call the tropical cyclones.

Tropical cyclones are warm-core low pressure systems associated with a spiral inflow of mass at the bottom level and spiral outflow at the top level. They always form over oceans where sea surface temperature, also air temperatures are greater than 26°C. The air accumulates large amounts of sensible and latent heat as it spirals towards the center. It receives this heat from the sea and the exchange can occur rapidly, because of the large amount of spray thrown into the air by the wind. The energy of the tropical cyclone is thus derived from the massive liberation of the latent heat of condensation.

Tropical cyclone is defined as a non-frontal, synoptic-scale cyclone developing over tropical and sub-tropical waters at any level and having a definitely organized circulation. In other parts of the world, these are referred to as hurricanes, typhoons or simply tropical cyclones depending on the region. In the North Atlantic, Eastern North Pacific and South Pacific Ocean, they are called"hurricanes". In the bay of Bengal, Arabian Sea and Western South Indian Ocean, the name is"cyclonic". In the eastern part of the Southern Indian Ocean, it is "willy-willy", and in the Western North Pacific Ocean, they are called "typhoons".

Tropical cyclones can only form over oceans of the world except in the South Atlantic Ocean and the south eastern Pacific where a tropical cyclone could never be formed due to the cooler sea surface temperature and higher vertical wind shears. They develop at latitudes usually greater than 5° from the equator. They reach their greatest intensity while located over warm tropical water. As soon as they move inland, they begin to weaken, but often not before they have caused great destruction.

The Philippines is prone to tropical cyclones due to its geographical location which generally produce heavy rains and flooding of large areas and also strong winds which result in heavy casualties to human life and destructions to crops and properties. Thus, it is of utmost importance to have sufficient knowledge on such maritime phenomena for beneficial purposes. Number 1