Red sky at night (photograph)

‘With the summer we’re having, we’ve got to make the most of these brief fine spells’, John Hammond the BBC weather presenter has just reminded us in his evening round up. And here is a picture of the sky outside my house shortly after the sun dipped down an hour and a half ago at the end of a bright blue day.

We all know the ancient weather maxim, ‘red sky at night…’ and, as I’ve been busily reading about the atmosphere recently, I thought I’d put this scientific explanation up here.

“Rays of light from the sun come in all colours of the spectrum but some colours or wavelengths are easily scattered by tiny particles in the atmosphere. On a cloudless day at midday, for instance, a large amount of the incoming blue and violet wavelengths are scattered by the abundant oxygen and nitrogen of the air, making the sky look blue.

At sunset and sunrise, the solar radiation has to pass through a thicker chunk of the atmosphere to reach the observer on the ground. This results in an even greater selective scattering of blue and violet wavelengths of light, resulting in a proportionately greater amount of the redder wavelengths reaching the ground – hence the red skies at dawn and dusk.”

Here’s a link to the full piece. And while I’m going it’s been a rather good day for photographs. Here’s a beautiful one of the sun coming up this morning from Monica Shaw. Then this one, best of all, is from the new NASA mission and shows sunrise on Mars.

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