Cyclones are transferred energies equal to several megaton nuclear bombs, from the ocean to the atmosphere every year. Every year, nearly 70 to 90 cyclonic systems developers all over the globe. The Coriolis force that compels the surface winds to spiral towards the low pressure system. As Coriolis force is negligible in the equatorial belt between latitudes 5 degree north and 5 degrees south, cyclonic systems do not develop in this region.
What is Cyclone?
In meteorology, the term cyclone can be defined as the rapid inward circulation of air masses about a low pressure centre which is circling counter-clockwise in the northern hemisphere and clockwise in the southern.
Regional names of cyclone
1. Typhoons – China Sea
2. Tropical Cyclones- Indian Ocean
3. Hurricanes-Caribbean Sea
5. Wily Willies- Northern Australia
6. Baguio- Philippines
7. Taifu- Japan
How does a cyclone formed?
Cyclones are formed in low pressure area. The topography and the intensity as well as frequency of cyclones that could strike a coast decide the vulnerability of the place.
The temperature difference between the warm, rising and the cooler environment led to the rise of air to become buoyant and then moves to upward. Then the high pressure area fills the air in the low pressure area. This cycle continues as warm air rises and low pressure area filled with cool air. They build up over a period of time. The warm, moist air rises and cools the water in the air and forms clouds. The whole system of clouds and wind spins and grows, fed by the ocean’s heat and water evaporating from the ocean surface.
There are six factors responsible for the formation of cyclone: (1) Sufficient warm temperature at sea surface (2) atmospheric instability (3) impact area of Coriolis force so that low pressure can be develop (4) high humidity in the lower to middle levels of the troposphere (5) a pre-existing low-level focus or disturbance (6) low vertical wind shear.
Types of Cyclone
1. Tropical Cyclone: It is occur over tropical ocean regions. it is two types- Hurricanes and typhoons. Hurricanes are found in the Atlantic and Northeast Pacific, whereas typhoons are found in the Northwest Pacific. On the basis of intensity and wind speed, this cyclone is classified into five categories- 1, 2, 3, 4 or 5. Category 5 has wind speed of 155 mph or above.
2. Polar Cyclone: It is occur over Polar Regions of Greenland, Siberia and Antarctica. It is strong during winter season.
3. Mesocyclone: It is a vortex of air within a convective storm. It is air that rises and rotates around a vertical axis, usually in the same direction as low pressure systems in a given hemisphere. These types of cyclones are accompanied by the rotating air within the thunderstorm.
Cyclone Prone area in India
India is highly vulnerable to natural hazards like earthquakes, floods, drought, cyclones and landslides. According to the meteorological department, there are 13 coastal states and Union Territories in India are Cyclone prone region. Four states like West Bengal, Andhra Pradesh, Odisha, Tamil Nadu-and one UT Puducherry on the east coast and Gujarat on the west coast are more vulnerable.
Cyclone Warning System in India
The India Meteorological Department is the nodal agency in india is responsible for meteorological observations, weather forecasting and seismology. A cyclone in the Bay of Bengal is predicted by the Area Cyclone Warning Centres (ACWC) and in the Arabian Sea is predicted by the Cyclone Warning Centre (CWC). Both ACWC and CWC sent their report to the coordinating centre, i.e., National Cyclone Warning Centre (NCWC).