Letter: Sunsets

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Indy Lifestyle Online
Sir: You may have improved your presentation in the "new look" Independent but your scientific explanations have not kept pace.

You say (23 September) "any object placed in water displaces its weight in water". This is not true. An object that sinks displaces less than its weight in water whilst one that floats is capable of displacing at least its own weight of water.

Last week on your weather page you suggested that the red of the evening sun was due to the larger dust particles in the atmosphere scattering the long wavelength red light more than the shorter wavelength blue light.

Lord Rayleigh gave a better explanation. He suggested that blue light, because its wavelength is only about half that of red light, is almost 16 times as likely to be scattered. This means that the light from the sun which has travelled through a large thickness of atmosphere (as it does in the morning and evening) is very deficient in blue light (which has been scattered) and so appears red (very little of which has been scattered).

John Senior

Huddersfield, West Yorks

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