NEW! The Gist (FREE) | E-BOOKS |
Aerosol : Environment for UPSC Exams
Aerosol : Environment for UPSC Exams
- The Aerosols are minute particles suspended in the atmosphere. When these particles are sufficiently large, we notice their presence as they scatter and absorb sunlight. Their scattering of sunlight can reduce visibility (haze) and redden sunrises and sunsets.
- An aerosol is a colloid of fine solid particles or liquid droplets, in air or another gas.
- Aerosols can be natural (fog, forest exudates and geyser steam) or artificial (haze, dust, particulate air pollutants and smoke).
- Aerosols interact both directly and indirectly with the Earth's radiation budget and climate.
- As a direct effect, the aerosols scatter sunlight directly back into space.
- As an indirect effect, aerosols in the lower atmosphere can modify the size of cloud particles, changing how the clouds reflect and absorb sunlight, thereby affecting the Earth's energy budget.
- Aerosols also can act as sites for chemical reactions to take place (heterogeneous chemistry). The most significant of these reactions are those that lead to the destruction of stratospheric ozone.
- During winter in the Polar Regions, aerosols grow to form polar stratospheric clouds. The large surface areas of these cloud particles provide sites for chemical reactions to take place. These reactions lead to the formation of large amounts of reactive chlorine and, ultimately, to the destruction of ozone in the stratosphere.
- Three types of atmospheric aerosol have a significant effect on Earth's climate: volcanic; desert dust; and human-made.
- Volcanic aerosol forms in the stratosphere after an eruption as droplets of sulfuric acid that can last up to two years, and reflect sunlight, lowering temperature.
- Desert dusts, mineral particles blown to high altitudes, absorb heat and may be responsible for inhibiting storm cloud formation.
- Human-made sulfate aerosols, primarily from burning oil and coal, affect the behavior of clouds.