Debate Magazine

Red Sky at Night...

Posted on the 09 January 2014 by Markwadsworth @Mark_Wadsworth
An article in The Daily Mail featuring photographs of some polar bears watching the sky turn red as the sun sets reminds me of something else which has been bugging me recently.  We know that the explanation for red sunsets is down to the scattering of light by molecules and particles in the atmosphere, blue and UV light is scattered more and red and yellow light is scattered less, see e.g. Science Daily  One of those TV scientists (Coxy, I think) demonstrated this by filling a long fish tank with very diluted milk and shining a white light in at one end. The milk solution at that end appeared blue-ish and at the other end appeared orangey-yellow.  So that's all perfectly plausible - but this explanation suggests that the sun/sky would be the same red-orange color at sunrise as it is at sunset. I'm no early riser, and have seen far fewer sunrises than sunsets in my life, but by and large, I have seldom noticed that red-orange effect in the morning, it's much more noticeable at sunset.  Have I missed something or does everybody else have the same impression? (I can think up a perfectly plausible explanation for this, which might or might not be nonsense - during the day, more particles are emitted, more dust is thrown up etc, and as the sun warms the atmosphere, it creates convection currents which stir it all up, so at sunset, the sun is shining through the muck it has spent all day churning up.  During the night, the atmosphere cools and settles, and most of the particles and dust sinks back to the ground, so in the morning the sun is shining through relatively clean air again, so there is less scattering of the blue and UV light.)

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