MANZOOR AHMAD BHAT
Today we would try to understand the meteorological conditions which are responsible for making our air murky during winters. There could be many reasons behind it. The most important being the temperature inversion. In temperature inversion, the air warm air lies above the cold air. The condition happens during the winters. In winters during nights the earth cools down faster than the air above it, leaving the cold air below the warm air. Such a condition is termed as temperature inversion. The temperature inversion makes the atmosphere stable. Though the stability is conditional only, which means atmosphere will be stable as long as the temperature inversion exists. In stable atmosphere, the vertical mixing of the pollutants is stopped. So the pollutants remain trapped in the ground layer of the atmosphere, which cause serious health hazards. Further more the horizontal movement of air is low at ground surface. Which would result in slow dilution of the pollutants into the atmosphere. Both these conditions sum up to aggravate the pollution problem during winters. This is the reason that the people suffering from respiratory disorders are having hard times during winters. Usually fog is associated with the inversion, as the temperature is below the dew point of water vapour. This is the reason for poor visibility during the winters. Relative humidity is the precursor for the development of the fog and corrosion of metal surface. The sun rays during these winters would lead the episodes of photochemical smog. Which is a serious health hazard. The sun rays also helps in generation of ground ozone, which is commonly called as bad ozone. It is having harmful effects on the plants, animals and the environment.
The unstable atmosphere encourages the upward movement of the air pollutants. The air pollutants move upwards and as they move upwards they are drifted to different regions by the fast moving winds which usually occur at a hieght of around 200 to 300 m. The unstable atmosphere takes away the pollutants from the breathing zone of the humans.Thus preventing humans from different respiratory disorders. Further the dilution helps in making the air cleaner comparatively. Wind is also an important factor which helps in dilution of the pollutants. The wind takes away the pollutants rapidly from the source and hence preventing the exposure to higher concentration of pollutants. The greater the hieght of the chimneys, greater are the chances pollutant dilution due to convective currents. The lower hieght hieght of the chimneys adds to the woes of air pollution.
The surface winds cause different types of eddie’s due to changes in climatic conditions and the topography of the area. These winds having varying speeds and directions are called turbulence. The turbulence cause the instability of the atmosphere which helps in vertical movement of the pollutants. Thus resulting in the dilution of the pollutants in the atmosphere. Rains helps in improving the air quality. The wet deposition of the pollutants occurs due to rains. The rain brings down the particulate matter and gases soluble in water to the surface, hence making the air clean of pollutants.
Manzoor Ahmad Bhat,Faculty EVS, Sankoo campus, GDC Kargil , can be reached at bhat.manzoor2008@gmail.com
