Wednesday 6 December 2023

Nine people dead after Cyclone Michuang makes landfall in Andhra Pradesh.

Nine people have been confirmed dead after Cyclone Michuang made landfall to the south of the city of Bapatla in southern Andhra Pradesh on Tuesday 5 December 2023. The storm made landfall at about 12.30 pm local time, bringing with it winds of up to 110 km per hour, and causing flooding along large parts of the coasts of Andhra Pradesh, Tamil Nadu, Telangana and Odisha. Around 9000 people were evacuated from coastal areas in Andhra Pradesh and 61 600 in Tamil Nadu. One person was killed in Andhra Pradesh, described as a four-year-old child crushed by a falling wall. In Tamil Nadu a further eight people died during the storm, including two people killed when a poultry unit collapsed in Eluru District and a police officer struck by a falling tree in the Siddavatam Forest.

Flooding in Chennai, Tamil Nadu, on Tuesday 5 December 2023.  Jothi Ramalingam/The Hindu.

Tropical storms, called Cyclones in the Indian Ocean and South Pacific, are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere. These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

The formation of a tropical cyclone. Natural Disaster Management.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms. 

The formation and impact of a storm surge. eSchoolToday.

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