Climate Class Aerosols Scientists are paying more attention these days to a long-neglected part of the atmosphere, one that has complex but important effects on climate aerosols. Aerosols are microscopic particles such as dust or soot that are sometimes so light they float in the atmosphere for a long time before they settle out. There are many kinds of aerosols, and they affect climate in complex ways. Get the image of a spray can out of your head. Those spray cans originally got the name because they produced droplets so fine they were suspended in the air.
Aerosols can be wet or dry liquid or solid.
Some aerosols floating in the atmosphere come from natural sources windblown soil, volcanic eruptions, or even the spray from crashing surf. Others, however, result from human activity. While disturbance of soils by humans can be a significant source of aerosols, most of the aerosols put into the atmosphere by humans result from burning something. In other words, smoke. Many of the particles in smoke are comparatively large or heavy and settle out quickly, falling close to the source.