How are cyclones categorised? Know about the Indian Ocean cyclone season

Atmospheric disturbance around a low-pressure area causes the formation of cyclones which is distinguished by rapid and often destructive air circulation. With cyclones come violent storms and bad weather.

There are two classifications of cyclones namely, extra tropical cyclones and tropical cyclones. While extra-tropical cyclones mainly form in polar regions and temperate zones, tropical cyclones form between the Tropics of Capricorn and Cancer.

India witnessed a twin cyclonic storm – Cyclone Tej and Cyclone Hamoon – recently. While Cyclone Tej formed in the Arabian Sea, Cyclone Hamoon formed in the Bay of Bengal.

The Indian Meteorological Department has formulated the criteria to classify the low pressure systems in Bay of Bengal and the Arabian Sea. The classification is based on the capacity to damage and their wind speeds, with the distinctions as follows:

Low Pressure: Less than 31 (in m/s), Less than 17 (in knots)Depression: 31-49 (in m/s), 17-27 (in knots)Deep Depression: 49-61 (in m/s), 27-33 (in knots)Cyclonic Storm: 61-88 (in m/s), 33-47 (in knots)Severe Cyclonic Storm: 88-117 (in m/s), 47-63 (in knots)Super Cyclone: More than 221 (in m/s), More than 120 (in knots)

North India goes through a season of tropical cyclone formation. Though there is no official bound to the season, it usually forms between April and December and peaks from May to November.

In the month of June, Cyclone Biparjoy formed over the Arabian Sea which intensified into a depression and later upgraded into a deep depression.

Currently, Cyclone Tej formed a cyclonic circulation in the Arabian Sea along with Cyclone Hamoon in the Bay of Bengal. Cyclone Hamoon upgraded to a cyclonic storm on October 23.