What is a cyclone?听
A cyclone is the same as a hurricane听or typhoon. Its name indicates which ocean it is听in.听Cyclones, hurricanes and typhoons are all听weather events听called听tropical cyclones. A cyclone is a tropical storm听that forms in the Indian Ocean.听If you would like to learn more about the distinction between these听classifications,听the听BBC Bitesize听webpage听 explains the听differences听between these 鈥榩owerful spinning听storms鈥�.听
What happened last month?听
In November 2020, a cyclone called Nivar hit India, only the third cyclone to make landfall since May earlier this year听(when听storm听Amphan听hit south east Asia, the biggest cyclone in two decades).听
Cyclone Nivar听is听a severe听tropical cyclone听which formed in the Bay of Bengal听and听struck the听southeast听coast of India听between 26 and 28听November听2020.听The tropical cyclone struck Puducherry,听a听district听in Tamil Nadu,听with a听population of听1.6 million听people.听
After making landfall听at around 10.30 pm on 25 November,听cyclone Nivar听weakened听from 鈥榲ery severe鈥櫶齮o听only 鈥榓 severe cyclonic storm鈥� and moved听northwards听inland.听It particularly effected听Chennai in听Tamil Nadu and听Andhra Pradesh听further up the coast.听听
Warnings were issued听to听coastal areas and fishermen were advised not to go out to sea.听
听reported that 鈥榠ndependent scientists said warming of oceans due to climate change was leading to more intense cyclones and dangerous storm surges鈥� in the Bay of Bengal.听听
鈥楴ow we have a La Nina in the Pacific, that is cool conditions in the Pacific that makes the local environmental conditions favourable for cyclogenesis in the Bay of Bengal. During the last 40 years, six cyclones of听the听severest听cyclone category,听hit the Tamil Nadu coast in November. Out of these six, five of them coincided with La Nina like conditions in the Pacific.鈥欌��听
What were the impacts?听
A cyclone can lead to a huge loss of听life and听property, especially in low-lying areas.听The Indian Meteorological Service听forecast winds of between 120 to听130 kilometres per hour (75 to 81 miles per hour),听flooding,听damage听to听crops听and听plantations,听destruction of听buildings听and roads,听disruption to听power lines听and听the uprooting of trees.听
The Bay of Bengal hosts only 4% of the听total tropical cyclones听globally but听suffers听of the fatalities are听from this region.听听
Cyclone Nivar claimed four lives and several injured, with heavy rainfall, a 1 metre storm surge, fallen trees, blocked waterways and toppled electricity pylons making rescue operations difficult.听听
What was the听Indian response?听
The National Herald of India reported on 24 November that the Puducherry district administration imposed听prohibitory听orders to stop the movement of people in public, issuing the directive under Section 144听CrPc.听This was later rescinded听by 26 November.听听
On听25 November听before the cyclone made landfall,听mass evacuations were听coordinated听by Indian authorities听in the low-lying areas of south eastern India.听Around 2,000 people were evacuated in Puducherry alone.听
National Disaster Response Force听(NDRF)听rescue teams have been deployed with over 1000+ personnel听mobilised听specifically trying to encourage people to move to safer zones, away from vulnerable coastal villages.听The听NDRF听is a disaster-response agency in India. It is the largest singular and specialised disaster force in the world. They are largely deployed for floods, cyclones, building collapse and earthquakes in India.听
Advice from the NDRF was broadcast听in 3 simple听pieces of information;听Are听you听cyclone ready? Switch off electrical gas/gas supply, keep doors and windows shut,听rely听only听on official warnings.听听
There were an estimated 175,000 people in rescue shelters听by听Wednesday night, 25 November.听
The听government in Tamil Nadu open sluice gates in a lake near Chennai as a precautionary听measure against metropolitan flooding in the city.听The听authorities听also declared a public holiday on Thursday, 26 November to听limit travel and听avoid the disastrous flooding of 2015 when 400 people听were killed.听听
Sizeable environmental destruction also occurred with over 1000 trees being uprooted by the storm.听
Mathematics and Data Skills听
Can you chart the course of cyclone Nivar? If you can it would be an excellent test of both numeracy and your knowledge of latitude and longitude.听Use听听漏 Nations Online Project听(which helpful identifies Puducherry, where cyclone Nivar made landfall)听and听听漏听Weather Underground,听to chart how this tropical storm developed.听
An example of a听complete听cyclone tracker听map听 漏 The India Meteorological Department听is below听to听illustrate听how听it should look.听
Alternatively,听sketch听the听choropleth map for Thursday 25 November听below听漏听the Weather Channel.听It shows the amount of rainfall in mm听after cyclone Nivar made landfall. Can you replicate the colour coded data?听
Further reading听
Nivar makes landfall听听听
Emergency ban on gatherings declared as storm bears down on Indian city听听
Landfall triggers torrential downpours听听
One dead and torrential rains as huge storm surge makes landfall in India听听
Prohibitory听orders clamped in Puducherry to restrict movement of people听听
Tens of thousands evacuated in southeast India听听
Over 1000 trees unrooted, say officials听听