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    Crepuscular rays
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   Rays & Shadows 

Dust, small aerosols and moisture droplets scatter light to make the sun's rays visible and cloud and mountain shadowed air dark by comparison. Air and very small particles scatter colours selectively to paint the blues of skies and fires of sunsets. Air at varied temperatures and densities refracts the rays of setting suns and moons to fashion fantastic shapes and green flashes. Perspective generates apparent glows around shadows even on the airless Moon.