Moreover, the speed of winds was also moderate to strong most of the time. Whenever, wind speed is on the higher side, it is difficult for pollutants to remain suspended for longer durations. Since the last two days, Delhi and the NCR region have been receiving moderate to heavy showers.
Despite these rains, there has been a significant increase in the pollution levels. The reason in sudden increase of pollution levels can be attributed to increased humidity levels and low temperatures. Whenever moisture content is high and temperature drops, it leads to condensation of water vapour present in the atmosphere and a layer of haze is formed at the earth’s surface.
Another factor that contributes in the increase of pollution levels is low wind speed or winds of a calmer pace. The dust, smoke particles and other pollutants get mixed with haze and remain suspended near the earth’s surface for longer durations as the wind speed remains low.
Thus, this type of condition will continue over Delhi and the NCR for at least the next two to three days. Thereafter, winds will start changing course and will blow from west or the northwest direction. These westerly winds are dry in nature which will reduce the humidity levels, sky will become clearer, day temperature will rise, and wind speed will pick up leading to dispersal of pollutants resulting in fall in pollution levels.
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