Atmospheric particulates (also called aerosols) are microscopic particles of solids or liquids that are suspended in a gas - think of dust motes floating in a sunbeam. There are many natural sources of atmospheric particulates: dust blown into the air by the wind, salts splashed into the air by sea spray, and soots from volcanoes and forest fires.
Humans also produce particulate matter that ends up in the atmosphere. The biggest sources are burning fossil fuels, such as in cars and smokestacks, and blowing dust created when vegetation has been removed for construction or grazing purposes.
It is very difficult to observe or measure atmospheric particulates directly, so as a result, scientists must use models to determine how they fit into the climate picture. Aerosols do affect climate, because they change the way energy moves through the atmosphere. Some, like sulphates, are actually thought to decrease the effects of global warming. However, sulphates in the air are a primary cause of acid rain, so there are no plans to begin pumping them into the atmosphere in order to alleviate climate change.
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