The National Disaster Management Authority classifies cyclones broadly into two categories: extratropical cyclones and tropical cyclones. Here is what you need to know about them.
Developed in the Arabian Sea, cyclone Biparjoy, earlier expected to move towards the Pakistan coastline, has now changed its path and is heading towards the northern Gujarat coast with landfall expected on June 15.
According to India’s Regional Specialised Meteorological Centre (RSMC), the cyclone might cause storm surges of 2-3 metres in height, destruction of thatched houses, damage to pucca houses and roads, floodings, widespread damage to standing crops, plantations and orchards, and disruption of railways, powerlines and signalling systems in the northern and western coastal districts of Gujarat.
Cyclone Biparjoy, which is expected to generate wind speeds of 125-135 kmph with gusts reaching up to 150 kmph by the time it reaches land, is a tropical cyclone. The National Disaster Management Authority classifies cyclones broadly into two categories: extratropical cyclones and tropical cyclones. Here is what you need to know about them.
First, what is a cyclone?
A cyclone is a large-scale system of air that rotates around the centre of a low-pressure area. It is usually accompanied by violent storms and bad weather. As per NDMA, a cyclone is characterised by inward spiralling winds that rotate anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
What are extratropical cyclones?
Also known as mid-latitude cyclones, extratropical cyclones are those which occur outside of the tropic. They have “cold air at their core, and derive their energy from the release of potential energy when cold and warm air masses interact”, according to the US National Oceanic and Atmospheric Administration (NOAA). It added that such cyclones always have one or more fronts — a weather system that is the boundary between two different types of air masses. One is represented by warm air and the other by cold air — connected to them, and can occur over land or ocean.
What are tropical cyclones?
Tropical cyclones are those which develop in the regions between the Tropics of Capricorn and Cancer. They are the most devastating storms on Earth. Such cyclones develop when “thunderstorm activity starts building close to the centre of circulation, and the strongest winds and rain are no longer in a band far from the centre,” NOAA noted. The core of the storm turns warm, and the cyclone gets most of its energy from the “latent heat” released when water vapour that has evaporated from warm ocean waters condenses into liquid water, the agency added. Moreover, warm fronts or cold fronts aren’t associated with tropical cyclones.
Tropical cyclones have different names depending on their location and strength. For instance, they are known as hurricanes in the Caribbean Sea, the Gulf of Mexico, the North Atlantic Ocean and the eastern and central North Pacific Ocean. In the western North Pacific, they are called typhoons.
Source: Indian Express, 13/06/23
