A hosted post from Dr. J. Vanderlei Martins ? JCET/UMBC - NASA GSFC
The air that we breath every day is primarily composed of gas molecules, but it also contains a large variety of suspended solid and liquid particles. These particles in suspension in the atmosphere are called aerosols. Aerosols are present in many aspects of our daily life. When we see smoke from a fire, truck exhaust, cigarette, etc., we are usually observing the effects of light being scattered and absorbed by aerosol particles rather than gas molecules. Similarly, aerosol particles interact with solar radiation scattering and absorbing energy that contributes to the heating or cooling of our planet. Aerosols are also essential for the formation of clouds droplets on Earth, acting as condensation nuclei for the water vapor molecules.
This figure below
The black circles showed in each figure correspond to filter pores, while the aerosol particles are showed in white or gray tones. The scale on the bottom of each image shows a 1 micrometer reference for the particle size. The mineral dust particles in a) are irregular and relatively large compared to the remarkably spherical and relatively small smoldering particles from biomass burning. The biomass burning particles are primarily composed by transparent organic material with a smaller fraction (5-20%) of an efficient light absorbing material called “black carbon”. The cluster aggregate can reach several tens of micrometers near the fire but they usually won't last very long in the atmosphere, usually breaking in smaller pieces or condensing in more compact particles. Particularly in the Amazon, these large clusters have not been observed more than a few miles downwind from the fire. The China pollution particles, collected by in collaboration with the University of Maryland Baltimore County and College Park, are composed of a blend of spherical particles and irregular and complex cluster aggregates.Posted by Ray Hoff at June 5, 2005 7:07 PM