by Goutham Krishna
Tropical cyclones can be defined as rapid rotating storms originating over warm tropical and subtropical oceans, with a low-pressure centre and the presence of spiralling clouds in the surroundings. They are one of the most devastating natural hazards that can cause immense damage once it makes landfall. The Arabian Sea and Bay of Bengal, situated in the north Indian ocean, are part of an active cyclone basin. Though it is the least active basin only contributing to 7% of the world’s tropical cyclones, its impact is high due to the densely populated coastal line bounding it.
The major driving force behind the formation of a tropical cyclone is the transfer of water vapour and heat from the warm ocean waters to the atmospheric air primarily by evaporation. The pressure difference developed as an effect of this warm rising air results in the formation of tropical cyclones. The temperature of the sea surface, geographical location, atmospheric temperature etc. are key factors with important roles to play in the formation and strength of these cyclones.
The Indian Ocean is the warmest ocean in the world with an average sea surface temperature ranging from 19-30 degrees Celsius. Hence the tropical waters of the Indian ocean are highly prone to the formation of tropical cyclones. Generally, the cyclones formed in the North Indian Ocean tends to move either in the South-west direction or in the North-East direction, according to the winds. In the Arabian sea, they are most likely to move in the north-western direction, targeting the Arabian Peninsula, whereas some may move in the North-East direction towards the Gujarat / Maharashtra coast. In the Bay of Bengal, storms generally move in the North-westwards before making landfall and then change direction into North-East.
Since the Western and Eastern coasts of India are densely populated with cities, commercial and industrial centres etc. the impact of cyclones if it makes landfall will be high. Cyclone Tauktae can be taken as the most recent example of disastrous cyclonic storms. Taukte, which made landfall in the state of Gujarat in May 2021 caused at least 169 deaths and damage around 40,000 crore rupees. Heavy rainfalls following these cyclones are also disastrous as it causes coastal flooding in the impacted area. Due to global warming and climate change, the frequency and intensity of tropical cyclones are likely to increase in the near future. An increase in temperature will lead to increased surface sea temperature and also will maximize the vapour content in the atmosphere and both of these will contribute enhance the intensity and frequency of cyclones.
Presently, India has advanced cyclone detection systems through which it is possible to forecast and detect each and every potential cyclonic threat at its stage of infancy. Forecasts regarding cyclones are given by six cyclone warning centres located at Kolkata, Bhubaneswar, Visakhapatnam, Chennai, Mumbai and Ahmedabad. Each of these centres has its own area of operation, which cumulatively covers total coastal stretch of the country. These systems have helped to reduce the impacts and damages of tropical cyclones to a large extent. But still, a cyclone is one of the most disastrous forms of natural disaster which always has a smell of fear and panic associated with it.
India Ocean Project 