Cyclone Mocha building over Bay of Bengal
Source: By The Indian Express
The Indian Meteorological Department (IMD) has said that a cyclonic or low-pressure area is developing in the Bay of Bengal. It also said that the weather system was likely to form a depression over the southeast Bay of Bengal around 9 May, and then intensify into a cyclonic storm.
This weather system will be called Cyclone Mocha (pronounced ‘Mokha’). Southern states are also expected to witness rainfall. It has been predicted that there may be moderate rainfall at most places during these days, with scattered heavy to very heavy rainfall likely over Andaman & Nicobar Islands.
What is a cyclone and how are they formed?
A cyclone is a low-pressure system that forms over warm waters. Usually, a high temperature anywhere means the existence of low-pressure air, and a low temperature means high-pressure wind. But what does this mean?
These differences have to do with how ascending and descending air behaves notes the United Kingdom’s Met Office website. As air gets warms over hotter regions it ascends, leading to low pressure at the surface it is covering. When air cools in colder areas it descends, leading to high pressure at the surface. In a depression or low-pressure situation, the air is rising and blows in an anticlockwise direction around the low in the northern hemisphere and in a clockwise direction in the southern hemisphere. The is because of the Coriolis effect, a result of the earth’s rotation on its axis. As warm air rises and cools, water vapour condenses to form clouds and this can lead to rains.
Weather systems formed over the Bay of Bengal in the peak of summer in May are among the strongest in the North Indian Ocean region. Warm seas present ripe conditions for the development and strengthening of cyclones and fuel these systems over the water.
According to the World Meteorological Organization, “Tropical cyclones are one of the biggest threats to life and property even in the formative stages of their development. They include a number of different hazards that can individually cause significant impacts on life and property, such as storm surge, flooding, extreme winds, tornadoes and lighting. Combined, these hazards interact with one another and substantially increase the potential for loss of life and material damage.”
How are cyclones named?
Cyclones that form in every ocean basin across the world are named by the regional specialised meteorological centres (RSMCs) and Tropical Cyclone Warning Centres (TCWCs). There are six RSMCs in the world, including the India Meteorological Department (IMD), and five TCWCs.
As an RSMC, the IMD names the cyclones developing over the north Indian Ocean, including the Bay of Bengal and the Arabian Sea, after following a standard procedure. The IMD is also mandated to issue advisories to 12 other countries in the region on the development of cyclones and storms.
In 2000, a group of nations called WMO/ESCAP (World Meteorological Organisation/United Nations Economic and Social Commission for Asia and the Pacific), which comprised Bangladesh, India, the Maldives, Myanmar, Oman, Pakistan, Sri Lanka and Thailand, decided to start naming cyclones in the region. After each country sent in suggestions, the WMO/ESCAP Panel on Tropical Cyclones (PTC) finalised the list.
This cyclone will be named Mocha (Mokha), a name suggested by Yemen after the Red Sea port city, which is known to have introduced coffee to the world over 500 years ago.
