Clouds Formation Creates A Horse

Other colors occur naturally in clouds. Bluish-grey is the result of light scattering within the cloud. In the visible spectrum, blue and green are at the short end of light's visible wavelengths, while red and yellow are at the long end. The short rays are more easily scattered by water droplets, and the long rays are more likely to be absorbed. The bluish color is evidence that such scattering is being produced by rain-sized droplets in the cloud.
A greenish tinge to a cloud is produced when sunlight is scattered by ice. A cumulonimbus cloud emitting green is an imminent sign of heavy rain, hail, strong winds and possible tornadoes. Yellowish clouds are rare but may occur in the late spring through early fall months during forest fire season. The yellow color is due to the presence of pollutants in the smoke.