Sunset rays - Ontario, Canada

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Sunset rays Ontario, Canada by Lauri Kangas (site) 9th September 2002. ©2002 Lauri A Kangas.

The rays appear to radiate upwards because of perspective effects. In reality they
are slanting gently downwards to reach the ground behind the camera .

Lauri's colour essay tells us much about light and the atmosphere. The sunset colours result from light scattered by very small dust and aerosol particles and the air itself. The scattering is greatest when the sun is low and its rays traverse long distances through the air. Shorter wavelength blue light is scattered more strongly than red leaving the sun's residual transmitted rays rich in reds and orange.

The rays show this reddening by their warm pinkish hues contrasting with the background blue scattered light from the sky. The rays themselves are made visible by scattering, but that they retain the sun's reddened hues indicates that their light was scattered by relatively large water droplets or aerosols in the lower atmospheric levels. These particles are Mie scatterers; unlike very small particles they do not preferentially scatter blues and other shorter wavelengths.

The cloud undersides are dark because the near horizontal sunlight does not penetrate them. Some of their rims have traces of "silver linings".

The dimmer water reflections appear to have deeper colours. When searching the sky near the sun for halos, iridescent clouds and coronae it is useful to view it by reflection in water.

Look carefully at the sun and nearby trees and their reflections. Reflected scenes are not "mirror images"! They differ from the real view because the effective eye positions for setting the perspective of reflected images is beneath the water ~ but that's another story!