This cartoon shows the relative sizes of a typical raindrop, a droplet of water in a cloud, an extremely large aerosol particle, and a smaller aerosol particle of a more typical size. Even smaller aerosol particles exist; some as small as 10 nanometers (0.01 microns) across. Those particles would be invisible at even this magnified size scale.
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Randy Russell / Windows to the Universe

Aerosols: Tiny Particulates in the Air

When you look up at the sky, you are looking at more than just air. There are also billions of tiny bits of solid and liquid floating in the air.

These tiny particles are called aerosols or particulates. Some of them are so small that they are invisible. Others are large enough to see, but they are still very small.

Some of them are natural. The dust from dry regions that is blown by the wind makes aerosols. Particles released by erupting volcanoes or forest fires make aerosols too. Salt from the ocean can also get into the air.

We, humans, add aerosols to the atmosphere too. Aerosols are a part of air pollution from cars, power plants, and factories.

Smaller and lighter aerosols can stay in the air longer than larger aerosols. Gravity can bring larger ones to the ground in a few hours. The smallest ones can stay in the air for weeks.

Aerosols affect Earthís climate. Aerosols help clouds form in the sky and the number and types of clouds affects climate. Certain types are able to scatter or absorb sunlight, which affects climate.

The aerosols that are from air pollution are bad for peopleís health. If the little particles get into a personís lungs it can make him or her very ill. Aerosols also cause haze in many parts of the world.

Last modified June 25, 2008 by Lisa Gardiner.

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