Gravito-photophoresis and aerosol stratification in the atmosphere

Particles larger than 1μm can be suspended in the atmosphere. They need to have a variation in accommodation coefficient over the surface. As a rule transparent particles should have a density smaller than the one of water. Both black particles and white particles can be levitated. Gravito-photophoresis explains the existence of narrow aerosol layers at altitudes of approximately 20 and 50km, and also at approx. 70 and 80-83km. The thickness of the layers can be less than 1km if the accomodation coefficient exhibits only small differences over the surface. Transparent particles may form thick layers above 50km rather easily.