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Atmospheric optics studies how light is redirected, scattered and absorbed by an atmosphere. Spatial changes of refractive index bend paths, suspended particles produce scattering of light, and moving variations of refractive index distort a distant source's wavefront.

The distinction is experimentally useful. A small source viewed through rising warm air changes shape and position even without an absorbing obstacle, while a cloudy beam path can lose direct radiant power through scattering of light. An optical telescope must therefore contend with both atmospheric transmission and changing optical aberrations; a large aperture alone does not guarantee a sharp image.