A resident wades through a flooded street after heavy rains in Chennai on December 4, 2023. Image Credit: AFP

Dubai: Five people were killed in rain-related incidents on Monday in south Indian state of Tamil Nadu as the cyclonic Storm 'Michaung' intensified into a severe cyclonic storm.

The Chennai airport, one of the busiest in India, will remain closed until 9am on Tuesday as the runway of Tamil Nadu’s largest city and a major electronics and manufacturing hub, lay submerged due to torrential rain.

The Tamil Nadu forest department has issued an advisory after a “mugger crocodile” was spotted on a Chennai road amid heavy rain. Additional Chief Secretary to Tamil Nadu Government Supriya Sahu on Monday re-shared a video, which was originally posted by Sun News, on X (formerly Twitter).

The now-viral clip shows a giant crocodile crossing the road near Velammal New Gen School in Chennai early this morning.

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Several areas of the city were under knee-deep water and there have been power outages since Monday morning, evoking memories of December 2015 when around 290 people died after catastrophic floods.

Michaung was expected to make landfall on the coast of the southern Indian state of Andhra Pradesh on Tuesday morning, the country’s weather office said, with sustained winds of 90-100kph (56-62mph), gusting to 110kph.

A waterlogged underpass in Chennai. Image Credit: ANI

What is the impact in Tamil Nadu?

Life was thrown out of gear in Chennai, and its neighbouring districts on Monday as relentless rains pounded various parts leading to inundation.

Cars were swept away as floodwater flowed through the streets, while its airport, one of the busiest in India, shut down operations for the day citing severe weather.

Media showed pictures of grounded planes with their wheels submerged in water as the rain pelted down. The IMD has forecast heavy to very heavy rainfall on Tuesday in north-coastal Tamil Nadu and Puducherry.

Chennai’s popular Marina Beach was flooded, and the roads from Mount Road to Marina Beach were blocked due to severe waterlogging.

The Tamil Nadu government has declared a public holiday in Chennai, Chengalpattu, Kancheepuram and Tiruvallur districts on Tuesday.

Taiwan’s Foxconn and Pegatron halted Apple iPhone production at their facilities near Chennai due to heavy rains, sources familiar with the matter told Reuters.

How bad is the situation in Andhra Pradesh?

Parts of Andhra Pradesh Are likely to get more than 200 millimetres (8 inches) of rain over the next 24 hours, India’s weather office said.

Authorities had evacuated nearly 7,000 people in eight coastal districts and were preparing to evacuate a total of 28,000, depending on the cyclone’s path and severity, a senior official in the state’s disaster management department said.

At least 800 people have been evacuated so far from Bapatla, the coastal town in Andhra Pradesh where the cyclone is expected to make landfall on Tuesday, P Ranjit Basha, district collector of Bapatla, said.

In the eastern state of Odisha, a number of districts experienced heavy rain, which authorities said could intensify on Tuesday.

What is the potential threat to crops?

Michaung is expected to mostly cause widespread crop damage in Andhra Pradesh. Paddy, pineapple and other standing crops, that are close to harvest, could be hit due to the heavy rainfall (over 200mm in 24 hours) during the next two days. Strong winds with speeds 90-100kph gusting to 110kph, expected during the cyclone’s landfall around Tuesday afternoon, could damage mature crops. In the eastern state of Odisha, a number of districts experienced heavy rain, which authorities said could intensify on Tuesday.

Image Credit: AFP file

So, what’s a cyclone?

A cyclone is a giant, spinning, whirlwind storm. They are called hurricanes in North America and typhoons in Asia.

In order for a cyclone to be identified as a cyclone, it must be travelling over 119kph and it must have been formed over the ocean in a tropical region. In order for a cyclone to form, the ocean waters need to be warm, at least 26°C. Above the warm ocean, water evaporates and forms clouds.

If there is low air pressure where the clouds are formed, it pulls them in and they begin to rotate. It is the earth rotating and spinning on its axis that causes the cyclone’s clouds to rotate. Clouds will continue to form and begin spinning more. This is the stage when it can develop into a mature cyclone, or lose its momentum.

Even if it has developed into a mature cyclone, it can still grow in size and increase its wind speed. In order for it to be categorised as a cyclone, its average sustained wind speed needs to exceed 63kph. To be classified as severe, the average sustained wind speed needs to exceed 118km per hour. Once a cyclone arrives over land, its strength weakens and it begins to fade out. This is due to the lack of moisture and heat compared to the ocean over which it was formed.

Why storm’s long sea travel makes the cyclone stronger?

Historically, weather systems originating from the Gulf of Thailand and the Malay Peninsula have been observed to undertake long sea journeys.

This characteristic makes these disturbances potentially stronger, with the risk of causing significant landfall along the coastlines of India, Bangladesh, and Myanmar. Tamil Nadu, Andhra, Odisha, West Bengal are particularly vulnerable to hazardous weather conditions.

How are cyclones named?

The World Meteorological Organisation (WMO) and member countries of the United Nations Economic and Social Commission (ESCAP) are responsible for naming each tropical cyclone.

The names of cyclones depend on the regional rules. “In the Atlantic and in the Southern hemisphere (Indian Ocean and South Pacific), tropical cyclones receive names in alphabetical order, and women and men’s names are alternated. In the Northern Indian Ocean, nations began utilising a new method for naming tropical cyclones in 2000; the names are listed alphabetically by country and are gender-neutral,” the WMO said.

Notably, the World Health Organisation generally keeps track of the names of different cyclones.

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Indian army rescues people from their flooded homes in Chennai Image Credit: ANI

How did the present cyclone get its name?

The term ‘Michaung,’ has been proposed by Myanmar, symbolises strength and resilience. The word is pronounced “Migjaum”.

Why is Cyclone Michaung unique?

Due to unfavourable ocean conditions, storms developing over the North Indian Ocean during December don’t attain destructive intensities. Therefore, cyclones of high intensity are uncommon in December. Initially the IMD forecast that Michaung will remain as a ‘tropical cyclone’ (wind speeds of 62 to 87kph) till it crossed the Andhra Pradesh coast.

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The flooded Tambaram Government Hospital in Chennai. Image Credit: AP

But on December 3, the IMD upgraded it to the intensity of a ‘severe’ storm (wind speeds of 88 to 166kph). Such intensification observed in a December cyclone is unique, the IMD said. It is above the normal value of the heat index, recorded off the south Andhra Pradesh coast, that has favoured Michaung to strengthen the cyclone, IMD officials said.

When is the cyclone season in the Bay of Bengal?

Cyclones in the Bay of Bengal typically occur between April and December. May witnesses a pre-monsoon surge in cyclonic conditions, while November experiences a post-monsoon peak. These months are particularly prone to the genesis of cyclones, creating hazardous weather conditions.

Why 2023 had unusual frequency of cyclones?

While it’s customary for around four storms to form annually in the Indian seas, this year has been exceptional. The present cyclonic storm ‘Michaung’ is the fourth to hit the Bay of Bengal this year, marking the sixth storm overall in Indian waters. Skymetweather reports that more storms are expected due to unfavourable weather conditions.