Particles, other than water or ice, suspended in the atmosphere ranging in radius from one-hundredth to one-ten-millionth of a centimetre -- or 102 to 10-3 microns (µ). Aerosols are important as nuclei for the condensation of water droplets and ice crystals, and as participants in various atmospheric chemical reactions. Perhaps most significantly, they absorb solar radiation, then emit and scatter it, influencing the radiation budget of the Earth-atmosphere system, which in turn influences the climate on Earth's surface. Aerosols from volcanic eruptions can lead to a cooling at the surface, which may delay greenhouse warming for a few years following a major eruption.