"made flickr EXPLORE"
Place: Red Berry Lake, SK, Canada
Why beautiful colors at sunset ?
The red hues of the sky at sunset and sunrise are caused by Mie
Scattering, not Rayleigh Scattering. The colours of the sky throughout
the day and at sunrise and sunset, are explained by the phenomena of
both Rayleigh Scattering and Mie Scattering. The colour of the sky
described by Rayleigh Scattering applies to the hues of blue, violet
and green, not to the reds, oranges, peaches and purples of sunrise
and sunset. Rayleigh Scattering is scattering of shorter wavelength
light (e.g. blue & violet) by air atoms and molecules (not
statistical variations in density of the Earth's atmosphere). The
magnitude or strength of Rayleigh Scattering varies by the reciprocal
of the wavelength raised to the fourth power, and hence does not
explain the beautiful variations of reds, purples, oranges and peachy
colours. The latter colours arise from Mie Scattering, low angle
scattering of light off dust, soot, smoke and (ash) particles. Mie
Scattering (producing the colours of sunset and sunrise) is
beautifully recognizable down-wind of and after dust storms, forest
fires and volcanic eruptions that inject large quantities of fine
particulate matter into the atmosphere.