What is a Typhoon?

A typhoon is a mature tropical cyclone with a spiral or circular system of strong winds that develops in the Western Pacific Ocean. It is usually hundreds of kilometres in diameter. Typhoons are measured on the Saffir-Simpson scale with category 1 being the lowest wind speed. Category 5 typhoons have the highest wind speeds. In the northern hemisphere, typhoons spiral in a counter-clockwise direction and in a clockwise direction in the southern hemisphere. The strongest typhoon season ever recorded occurred in 1964 when 39 typhoons formed. A typhoon in the Pacific can happen anytime throughout the year, but most typhoons happen between July and September.

The only positive thing a typhoon can bring is abundant rain in arid parts of the Pacific. On the negative side, it creates major damage through strong winds, salty winds, waves, floods, landslides, diseases and debris flow.

How does it form?

A typhoon is formed with the mixture of a sufficiently warm sea surface temperature, atmospheric instability, high humidity in the troposphere, enough Coriolis force to develop a low pressure centre and a low vertical wind shear. Typhoons can only form at latitudes that are more than 10 degrees north or south of the Earth’s equator where there is no Coriolis force.

How is it named?

Typhoons are not named after people but usually refer to animals, flowers or astrological signs. The submitted names are arranged into five lists, each list being renewed every year. Some typhoons can have two names. According to the sequence of their occurrence in the calendar, a great majority of typhoons is given a numerical designation in Japan.

Photo : Typhoon Haiyan, NASA Goddard Space Flight, http://flic.kr/p/hvY9d4, (CC BY 2.0)