The India Meteorological Department (IMD) has recently issued an orange alert, indicating the development of the deep depression, Cyclone Vayu. This cyclone, named by India itself, is in its early stage with the potential to grow into a stronger storm. As reported, Cyclone Vayu is approximately 250 km northwest of Amindivi island situated in Lakshadweep and roughly 750 km southwest of Mumbai, engulfed by the Arabian Sea.
The Current Scenario of Cyclone Vayu
At present, the cyclone seems to be moving northwards and looks set to impact the Gujarat coast. An interesting observation made by the IMD is that Cyclone Vayu might draw moisture away from the monsoon winds, causing a delay in the arrival of the annual monsoon. It’s expected that this cyclone will disrupt normal progress by attracting all the moisture from the monsoon winds towards itself.
Cyclones are maintained by robust low-pressure areas at their core. Winds in surrounding regions are compelled to rush towards these low-pressure areas. Similar low-pressure areas, if developed near or over land, can play a crucial role in drawing the monsoon winds over the country. However, the currently prevailing low-pressure area at the center of Cyclone Vayu is considerably more potent than any local system that could attract the northeast-bound monsoon winds.
Understanding Different Cyclonic Alerts
The IMD issues different alerts to ensure preparedness against cyclones. The Yellow Alert advises people to stay updated, whereas an Orange Alert suggests being prepared. The Red Alert urges taking action, and a Green Alert signifies no warning.
| Alert Colour | Meaning |
|---|---|
| Yellow | Stay Updated |
| Orange | Prepare |
| Red | Take Action |
| Green | No Warning |
Cyclonic Activity in the Arabian Sea
Cyclonic activity is less intense in the Arabian sea when compared to its counterpart, the Bay of Bengal, which frequently gives rise to high-intensity severe cyclones. Over the last 120 years, only about 14% of all cyclonic storms and 23% of severe cyclones around India have occurred in the Arabian Sea. Cyclones originating from the Arabian Sea are generally weaker than those from the Bay of Bengal.
The Gujarat coastline, where most Arabian Sea cyclones head, isn’t densely populated. This results in a comparatively lower damage potential from cyclones on the west coast.
Why the Bay of Bengal is More Prone to Cyclones
Several factors contribute to the Bay of Bengal being more cyclone-prone. These include the temperature difference, as cyclones require a continuous supply of heat energy, and the Bay of Bengal is warmer than the Arabian Sea.
Sea surface temperatures and humidity levels both significantly impact the possibility of cyclone formation. The Bay of Bengal experiences higher rainfall and constant freshwater inflow from the Ganga and Brahmaputra rivers. This consistent refreshing of surface water prevents the warm upper water layer from mixing with the cooler waters below, ideal for cyclone formation.
The Arabian Sea, on the other hand, receives stronger winds that help dissipate the heat, and the lack of constant fresh water supply allows the warm water to mix with the cool water, thereby reducing the temperature.
Another contributing factor to the increased cyclonic activity in the Bay of Bengal is the absence of a large landmass between the Pacific and the Bay. This open space permits cyclonic winds to easily move into the Bay of Bengal. Furthermore, low-pressure systems originating from the Pacific Ocean often move towards the Bay of Bengal.