Under the influence of two cyclonic circulations, moisture-laden winds have entered the north-eastern region and this situation caused widespread rainfall activities over Assam-Meghalaya and Nagaland-Manipur-Mizoram-Tripura (NMMT) meteorological (Met) sub-divisions on Saturday, covering almost all areas of the two Met sub-divisions.
The first cyclonic circulation, extending up to 0.9 km above mean sea level, is persisting over northern part of Gangetic West Bengal and neighbourhood, while the second cyclonic circulation, extending up to 0.9 km above mean sea level, is persisting over south Assam and neighbourhood.
Under the impact of both these systems, moisture-laden winds are reaching the lower atmospheric levels of the NE region. At present, the moisture-laden winds are reaching Assam-Meghalaya and NMMT. This is the reason why these parts of the region experienced widespread rainfall activities on Saturday. However, the situation will improve thereafter, sources in the Regional Meteorology Centre (RMC) here said.
It needs mention here that in the meteorological parlance, a cyclonic circulation (Cycir) is an atmospheric wind flow in upper levels associated with any low pressure system and under it, the wind flow is counter clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
A Low Pressure Area is an area in the atmosphere in which the pressures are lower than those of the surrounding region at the same level and is represented on a synoptic chart by a system of one closed isobar (wind speed on the surface < 17 Knots (Kts) when the system is at sea or one closed isobar in the radius of 3 Deg. from the centre over land).