Tyndall effect

An example in everyday life is the blue colour sometimes seen in the smoke emitted by motorcycles, in particular two-stroke machines where the burnt engine oil provides these particles.

[1] The same effect can also be observed with tobacco smoke whose fine particles also preferentially scatter blue light.

[1] Prior to his discovery of the phenomenon, Tyndall was primarily known for his work on the absorption and emission of radiant heat on a molecular level.

In 1902, the ultramicroscope was developed by Richard Adolf Zsigmondy (1865–1929) and Henry Siedentopf (1872–1940), working for Carl Zeiss AG.

Curiosity about the Tyndall effect led them to apply bright sunlight for illumination and they were able to determine the size of 4 nm small gold nanoparticles that generate the cranberry glass colour.

[4][5] Rayleigh scattering is defined by a mathematical formula that requires the light-scattering particles to be far smaller than the wavelength of the light.

[8] The color of blue eyes is due to the Tyndall scattering of light by a translucent layer of turbid media in the iris containing numerous small particles of about 0.6 micrometers in diameter.

When the day's sky is overcast, sunlight passes through the turbidity layer of the clouds, resulting in scattered, diffuse light on the ground (sunbeam).