Aerosol
Why In News ?
- Recently, a new analysis by the Physical Research Laboratory of the Indian Space Research Organization (ISRO) has revealed that a worrying increase in aerosol levels is being observed in the Hindukush-Himalayan-Tibetan Plateau region.
In terms of Aerosols:
- Aerosols are microscopic particles suspended in the atmosphere.
- When these particles are large enough, we notice their presence when they scatter and absorb sunlight. Their scattering of sunlight can reduce visibility (haze) and redden sunrises and sunsets.
- Aerosols are short-lived, unlike greenhouse gases which persist and accumulate in the atmosphere for long periods of time.
- Most aerosols are of natural origin, about 90% by mass. For example, volcanoes release huge columns of ash into the air, as well as sulfur dioxide and other gases, causing sulphates.
- The remaining 10% of aerosols are considered anthropogenic or man-made, and they come from a variety of sources.
- Automobiles, incinerators, smelters and power plants are prolific producers of sulphate, nitrate, black carbon and other particles.
- Deforestation, overgrazing, drought, and excessive irrigation can alter the land surface, increasing the rate at which dust aerosols enter the atmosphere. Even indoors, cigarettes, cooking stoves, fireplaces and candles are sources of aerosols.
Direct Effect of Aerosol:
- Aerosols interact directly and indirectly with the Earth’s radiation budget and climate.
- Different aerosols scatter or absorb sunlight to different degrees depending on their physical properties. Although most aerosols reflect sunlight, some also absorb it.
- The effect of aerosols on light depends mainly on the structure and color of the particles.
- Pure sulphates and nitrates reflect almost all radiation, cooling the atmosphere. In contrast, black carbon readily absorbs radiation, warming the atmosphere but also shading the surface.
- In the Arctic, aerosols from wildfires and industrial pollution are likely accelerating ice melt.
Importance of Aerosol:
- Aerosol mixed clouds, being brighter, reflect more energy received from the Sun towards space.
- The formation of these new particles covers 40 percent of the Earth’s surface. This means that aerosol particles are helpful in keeping the Earth’s temperature down, contrary to global warming.
- Understanding the formation of these particles in equatorial regions and their contribution to the characteristics of clouds will help us understand and develop climate models.
- The CIRES study shows that in remote areas where the air is cleaner, the influence of aerosol particles on cloud formation is greater.
Source – Down to Earth
