Tyndall effect

The Tyndall effect is the effect of light scattering on particles in colloid systems, such as suspensions or emulsions. It is named after the Irish scientist John Tyndall. The Tyndall effect is used to tell the difference between the different types of mixtures, namely solution, colloid, and suspension. For example, the Tyndall effect is noticeable when car headlamps are used in fog. The light with shorter wavelengths scatters better, thus the color of scattered light has a bluish tint. This is also the reason why the sky looks blue when viewed away from the sun: the blue light from the sun is scattered to a greater degree and is therefore visible far from its source.
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Noun
1. the phenomenon in which light is scattered by very small particles in its path; it makes a beam of light visible; the scattered light is mainly blue
(hypernym) optical phenomenon

Light passing through a colloid is scattered by suspended particles. The light beam becomes clearly visible; this phenomenon is called the Tyndall effect. For example, car headlight beams can be seen in fog, but the beams are invisible in clear air.