The Sunday Mail
Tropical cyclones are low pressure systems that form over warm tropical waters and have sustained winds of 63 km/h or greater and gusts in excess of 90 km/h near the centre.
The gale force winds can extend hundreds of kilometres from the cyclone centre.
If the sustained winds around the centre reach 118 km/h and gusts in excess of 165 km/h then the system is called a severe tropical cyclone.
Tropical cyclones are referred to as hurricanes or typhoons in other countries.
The circular eye or centre of a tropical cyclone is an area characterised by light winds and often by clear skies.
Eye diameters are typically 40 km but can range from under 10 km to over 100 km.
The eye is surrounded by a dense ring of cloud about 16 km high known as the eye wall which marks the belt of strongest winds and heaviest rainfall.
Tropical cyclones derive their energy from the warm tropical oceans and do not form unless the sea-surface temperature is above 26.5°C, although once formed, they can persist over lower sea-surface temperatures.
Tropical cyclones can persist for many days and may follow quite erratic paths.
They usually dissipate over land or colder oceans. — Internet sources
