The air quality index of Delhi and NCR continues to remain in the severe category. There has been a gradual increase in pollution levels in Delhi since last week. Wind speed is very light. It is between 3 and 5 Kmph, moreover, during the night and early morning hours, the wind becomes calm.
After the withdrawal of monsoon, the weather usually goes dry over Northwest India including Delhi and NCR. Western disturbances are the only weather systems which give rain activities over the Northern Plains during winter.
This year, we have not seen any significant rain over the plains of Northwest India in the month of October. The upper layer of the earth has gone completely dry. Loose dust is contributing to air pollution. The number of vehicles in Delhi and NCR is very high.
The smoke of vehicular traffic and industries along with the dust from construction sites is also contributing. Due to the low temperature here near the earth's surface become dense and heavy and due to the absence of moderate winds, pollutants are not able to disperse.
Another contributor to the pollutants is the smoke from Stubble Burning in the neighbouring states of Punjab and Haryana. After the withdrawal of the monsoon, the wind direction most of the time remains from the west and Northwest. Winds from the Northwest direction carry the smoke of stubble burning towards Delhi and NCR. Another factor is inversion. During inversion, the temperature starts rising with height.
When this happens, the winds near the Earth's surface become heavier than the winds above them. These heavy winds remain near the earth's surface and do not rise. The pollutants are trapped by these humid and heavy winds near the earth's surface leading to an increase in pollution.
Pollution can be reduced by strong winds from a particular direction for a prolonged period or rainfall. Unfortunately, we do not see the wind speed increase during the next 3 to 4 days. Chances of rain are also ruled out for at least one week.
