Context

Historically, waters off the western coast have experienced fewer storms than the Bay of Bengal, and typically weaker. This the third year in a row that cyclones in the Arabian Sea have menaced the west coast and frequency and of Cyclone is increasing in the Sea.

About

Why there is rise in frequency of cyclones in Arabian Sea?

• The recent frequency of cyclones was a clear sign of temperatures rising in the Arabian Sea.
• These low-pressure systems are formed when warm, moist air rises up from the sea surface.
• The rapid warming of the Arabian Sea is leading to not just more cyclones but also more extreme rain events.
• Due to these warm ocean conditions it is seen that the cyclone intensifies from a weak cyclone to an extremely severe cyclone rapidly.
• Currently, the sea water up to depths of 50 metres has been very warm that supplies the ample energy to enable the intensification of Cyclone Tauktae.
• The more heat released through condensation of water vapour results in the steeper drop in pressure that undergoes multiple stages of intensification to form cyclones.

Most recent cyclone in Arabian Sea- Tauktae

• Cyclone Tauktae (pronounced Tau-Te) is classified as a very severe cyclonic storm.
• Its speed is expected to increase to 150-160 km per hour, gusting up to 175 km per hour.
• Tauktae's name originates from a Burmese word which translates to gecko, a "highly vocal lizard".
• The cyclone was named by Myanmar.
• Tauktae is the fourth cyclone in consecutive years in the Arabian Sea, others being the Cyclone Mekanu in 2018, which struck Oman, Cyclone Vayu in 2019 struck Gujarat and Cyclone Nisarga in 2020 that struck Maharashtra.
• Tauktae has been intensifying very rapidly from a depression formed in the southeast Arabian Sea.

Categories of Cyclones The severity of a tropical cyclone is described in terms of categories ranging from 1 (weakest) to 5 (strongest) related to the maximum mean wind speed as shown in this table. Category Maximum Mean Wind (km/h) Typical Strongest Gust (km/h) Typical Effects Cyclonic Storm 63 - 88 < 125 Damaging winds. Negligible house damage. Damage to some crops, trees and caravans. Craft may drag moorings. Severe Cyclonic Storm 89 - 117 125 - 164 Destructive winds. Minor house damage. Significant damage to signs, trees and caravans. Heavy damage to some crops. Risk of power failure. Small craft may break moorings. Very Severe Cyclonic Storm 118 - 159 165 - 224 Very destructive winds. Some roof and structural damage. Some caravans destroyed. Power failures likely. (e.g. Clare, Olwyn) Extremely Severe Cyclone 160 - 199 225 - 279 Significant roofing loss and structural damage. Many caravans destroyed and blown away. Dangerous airborne debris. Widespread power failures. (e.g. Tracy, Debbie, Lam)  Super Cyclone > 200 > 279 Extremely dangerous with widespread destruction. (e.g. Vance, Marcia, Yasi)

Previous cyclones in Arabian Sea

• Cyclone Mekanu in 2018, which struck Oman
• Cyclone Vayu in 2019 struck Gujarat
• Cyclone Nisarga in 2020 that struck Maharashtra

Reason for more Cyclones formation over the Bay of Bengal The Bay witnesses cyclones both pre-monsoon and post-monsoon due to number of reasons; Higher sea surface temperature weak vertical mixing in BOB huge perennial fresh water influx from Himalayan Rivers basin rainfall and sluggish wind