Every year, air pollution in many urban industrial areas of North India from NCR not only becomes a respiratory and health problem, but now the question is also becoming acute whether this poisonous air also affects weather systems like western disturbances, cloud formation process and rainfall.
Scientific studies and climate experts say that extreme pollution can certainly impact local and regional weather, although this impact is not as simple as simply stopping rain, but works through a number of complex processes. According to reports by NASA, World Meteorological Organization (WMO) and IPCC, particulate matter PM 2.5, PM 10, black carbon and sulphate aerosols present in the atmosphere interact with the sun’s rays.
These particles sometimes reflect sunlight back into space and sometimes trap heat in the atmosphere. It has a direct impact on surface temperature, atmospheric stability and vertical wind speed, which are important factors determining the probability of rain. Excessive pollution can make the lower atmospheric layer colder and the upper layer relatively warmer, explains a senior climate scientist at IITM Pune.
This weakens the rise of air and hinders the process of cloud formation. Since Western Disturbances are basically large-scale weather systems, which run from Central Asia and reach North India. Experts clarify that pollution cannot stop these systems, because their energy and structure are very huge.
However, according to studies involving CSIR and IIT Delhi, when moisture arrives with western disturbances in highly polluted areas, aerosol particles can alter the microphysics of clouds. Due to this, the droplets remain smaller, it slows down their mixing and becoming heavy and sometimes rain occurs late or in less quantity.
The interesting fact is that it is not necessary that pollution always reduces rainfall. A joint study by IIT Kanpur and international research institutes suggests that, under certain circumstances, aerosol particles can make storm clouds more energetic, leading to increased occurrences of short-lived but extreme rainfall or hailstorms.
Combined effect of urban heat island and pollution
Heavy pollution is often associated with the urban heat island effect. Concrete, vehicle emissions and industrial activities make cities warmer than the surrounding rural areas. According to meteorologists, when heat islands and pollution meet, local wind direction, moisture distribution and the height of cloud formation can change, causing unstable weather patterns.
