Cyclone Vardah


Ajit Kumar AJIT KUMARWISDOM IAS, New Delhi.

Tropical Cyclone Vardah on December11, 2016  crossed Andhra Pradesh coast between Chennai and Ongole. This brought good rainfall over north coastal districts, including Chennai.

What is cyclone Vardah?

Originating in Southern Thailand, cyclone Vardah is a large scale air mass that had led to the death of about a dozen people there, before crawling towards India. In the past few days, the disturbances ensued in the islands of Andaman and Nicobar resulting in several tourists getting stranded there.
The main areas hit by the storm are Tamil Nadu and Andhra Pradesh.

What is a Tropical Cyclone?

Tropical Cyclones are low pressure systems that form over warm tropical waters and have gale force winds (sustained winds of 63 km/h or greater and gusts in excess of 90 km/h) near the centre. Technically they are defined as a non-frontal low pressure system of synoptic scale developing over warm waters having organised convection and a maximum mean wind speed of 34 knots or greater extending more than half-way around near the centre and persisting for at least six hours.

The gale force winds can extend hundreds of kilometres from the cyclone centre. If the sustained winds around the centre reach 118 km/h (gusts in excess 165 km/h). then the system is called a severe tropical cyclone. These 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.
 



Tuesday, 13th Dec 2016, 09:50:41 AM

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