The Effects of Aerosols had on Climate Changes.

Aerosols are tiny particles found in the air. Some occur naturally while some originate from volcanoes, dust storms, forest and grassland fires, living vegetation, and even sea spray. Human activities, such as the burning of fossil fuels and the alteration of natural surface cover, and fossil fuel burning also contributes to most of the emmitions of aerosols. Averaged over the globe, aerosols made by human activities currently account for about 10 percent or more of the total amount of aerosols found in our atmosphere.

Scientists have much to learn about the way aerosols affect regional and global climate but have yet to accurately quantify the relative impacts on climate of natural aerosols and those of human origin. Moreover, theye do not know in what regions of the planet the amount of atmospheric aerosol is increasing, is diminishing, and is remaining roughly constant. Overall, they are even unsure whether aerosols are warming or cooling our planet. In that sense, the effects of Aerosols are pretty much still hidden in its veil waiting for someone to unlock its sercret.

How Aerosols Affect Our Lives?

Aerosols tend to cause cooling of the Earth's surface immediately below them. Because most aerosols reflect sunlight back into space, they have a "direct" cooling effect by reducing the amount of solar radiation that reaches the surface. The magnitude of this cooling effect depends on the size and composition of the aerosol particles, as well as the reflective properties of the underlying surface. It is thought that aerosol cooling may partially offset expected global warming that is attributed to increases in the amount of carbon dioxide from human activity.

Aerosols are also believed to have an "indirect" effect on climate by changing properties of clouds. Indeed, if there were no aerosols in the atmosphere, there would be no clouds. It is very difficult to form clouds without small aerosol particles acting as "seeds" to start the formation of cloud droplets. As aerosol concentration increases within a cloud, the water in the cloud gets spread over many more particles, each of which is correspondingly smaller. Smaller particles fall more slowly in the atmosphere and decrease the amount of rainfall. In this way, changing aerosols in the atmosphere can change the frequency of cloud occurrence, cloud thickness, and rainfall amounts.

If there are more aerosols, scientists expect more cloud drops to form. Since the total amount of condensed water in the cloud is not expected to change much, the average drop must become smaller. This has two consequences -- clouds with smaller drops reflect more sunlight, and such clouds last longer, because it takes more time for small drops to coalesce into drops that are large enough to fall to the ground. Both effects increase the amount of sunlight that is reflected to space without reaching the surface.