How are low pressure system classified in India? What are the differences between low, depression and cyclone?
The low pressure system over Indian region are classified based on the maximum sustained winds speed associated with the system and the pressure deficit/ number of closed isobars associated with the system. The pressure criteria is used, when the system is over land and wind criteria is used, when the system is over the sea. The system is called as low if there is one closed isobar in the interval of 2 hPa. It is called depression, if there are two closed isobars, a deep depression, if there are three closed isobars and cyclonic storm if there are four or more closed isobars. The detailed classification based on wind criteria are given in the Table below. Considering wind criteria, the system with wind speed of 17-27 knots is called as depression and the low pressure system with maximum sustained 3 minutes surface winds between 28-33 knots is called a deep depression.
The low pressure system over Indian region are classified based on the maximum sustained winds speed associated with the system and the pressure deficit/ number of closed isobars associated with the system. The pressure criteria is used, when the system is over land and wind criteria is used, when the system is over the sea. The system is called as low if there is one closed isobar in the interval of 2 hPa. It is called depression, if there are two closed isobars, a deep depression, if there are three closed isobars and cyclonic storm if there are four or more closed isobars. The detailed classification based on wind criteria are given in the Table below. Considering wind criteria, the system with wind speed of 17-27 knots is called as depression and the low pressure system with maximum sustained 3 minutes surface winds between 28-33 knots is called a deep depression.
