Here is why Cyclone Biporjoy intensified into an extremely severe cyclonic storm

Subject: Geography

Section: Physical geography

Context:

A combination of factors helped Cyclone Biporjoy intensify from a very severe cyclonic storm to an extremely severe cyclonic storm.

Details:

Extremely severe cyclones form when wind speeds reach 168-221 kilometres per hour (kmph). As of June 12, the wind speeds were 165-175 gusting to 190 kmph.
A study recorded a 52 per cent increase in the number of cyclones in the Arabian Sea. And a 150 per cent increase in Very severe cyclones.
This increase has been linked to rising ocean temperatures and increased availability of moisture under global warming.
As the cyclone approaches the coast, it is expected to weaken into a very severe cyclonic storm as it crosses between Mandvi (Gujarat) and Karachi (Pakistan) near Jakhau Port (Gujarat) by noon on 15th June. The maximum sustained wind speed could be 125-135 kmph gusting to 150 kmph.

Intensification of Cyclone Biporjoy:

Cyclone Biporjoy has intensified twice in its lifetime. It is also the fourth longest-lived cyclone in the pre-monsoon region in the Arabian Sea since 1982.
Models were not able to predict its intensity much in advance due to certain fluctuations, which help the cyclone strengthen or weaken. These include upper air divergence, wind shear, and dry air.
The amount of wind shear is the change of the wind with height. The large amounts of wind shear generally weaken the cyclone intensification.
The shear towards the northern Arabian Sea has been weak and favourable for cyclone intensification.
The upper air divergence which happens when air flows (wind) away from a region, also helped the cyclone gain strength.
- It allows the cyclone to vent out the air and promotes its intensification
The sea surface temperature and ocean heat content also favour the cyclone formation.