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News: Cyclone Amphan has intensified into a super cyclonic storm and is expected to make landfall between West Bengal and Bangladesh close to Sundarbans.
- Cyclone Amphan is a tropical cyclone formed over Bay of Bengal that has turned into a super cyclonic storm.
- The Cyclone Amphan is also the strongest storm to have formed in the Bay of Bengal since the super cyclone of 1999 that ravaged Paradip in Odisha.
Why does the Bay of Bengal receive higher Cyclones compared to Arabian Sea?
- Higher Rainfall: Bay of Bengal receives higher rainfall which provides required humidity for cyclone formation.
- Location: The typhoons originating in the Pacific Ocean too influence the cyclones in BOB not the case in Arabian Sea.
- Constant Inflow of Fresh Water: The inflow from the Ganga and Brahmaputra rivers makes it impossible for the warm water to mix with the cooler water making it ideal for a cyclonic depression.
- Sluggish Winds: It keeps temperatures relatively high of about 28 degrees around the year.
Reasons responsible for intensification of Cyclones in Bay of Bengal:
- In 2020, the Bay of Bengal has observed record summer temperatures due to global warming from fossil fuel emissions that have been heating up oceans.
- However, such unusual warming around India is no longer restricted to just the BoB but also the Arabian Sea and the Indian Ocean.It makes storm prediction less reliable as well as disrupting monsoon patterns.
- Further, reduced particulate matter emissions during the lockdown resulted in fewer aerosols such as black carbon that are known to reflect sunlight and heat away from the surface.
Classification of Cyclones: The criteria followed by Indian meteorological Department(IMD) to classify Cyclones in the Bay of Bengal and in the Arabian Sea are as under:
|Types of Disturbances||Associated Wind Speed in the Circulation|
|Low Pressure Area||<31 km/hr|
|Deep Depression||50-61 km/hr|
|Cyclonic Storm||62-88 km/hr (Here,IMD assigns the name to Cyclone)|
|Severe Cyclonic Storm||89-118 km/hr|
|Very Severe Cyclonic Storm||119-221 km/hr|
|Super Cyclonic Storm||>222 km/hr|
Different Colour Codes:
- Green(No warning): No advisory is issued in such cases.
- Yellow(Be updated): It indicates severely bad weather panning across several days.It also suggests that the weather could change for the worse causing disruption in day-to-day activities.
- Orange/ Amber(Be prepared): It is issued as a warning of extremely bad weather with the potential of disruption.It is also a sign for people to prepare for evacuation and protect themselves from bad weather.
- Red(Take action): It is issued when the extremely bad weather conditions are certainly going to disrupt life.In this case, people must take all measures to protect their families and follow the instructions of local authorities and disaster-response teams.
- IMD:It was established in 1875 under the Ministry of Earth Sciences.It is the principal agency responsible for meteorological observations, weather forecasting and seismology.