Have you ever tried to take photographs when it’s almost dark, with a very long exposure? They always end up looking blue, like the one above. There is a good scientific explanation for this. It’s because of “Rayleigh Scattering”. The atmosphere absorbs shorter wavelengths of light the most, and this then this gets radiated across the sky. Blue is the shortest wavelength that our eyes are highly sensitive to, so the sky ends up looking blue. Indigo and Violet light is also affected the same way, but our eyes are less sensitive to both of these than to blue, and the sun produces slightly less of both of these colours as well. Otherwise, the sky would look a rather nice deep bluey-violety sort of colour.
Rayleigh Scattering is also why the sun looks yellow from earth: it looks white from out in space where there is no atmosphere. It even explains why the sun gets redder as it sets. The light is having to travel through more atmosphere, so there is greater absorption of green colours, just leaving the longer wavelength red to yellow colours to get through to our eyes.
When there is moisture or dust in the atmosphere, the absorption patterns vary and we get stunning multi-coloured sunsets with all sorts of colours. We get these a lot here because of the moisture in the air caused by the sea. The above picture shows this.
“Where The Blue Of The Night” is a song, originally sung by Bing Crosby. This is a fair version of it by Russ Columbo, but the reason I am posting this clip is for the gorgeous old record player:
http://www.youtube.com/watch?v=YzD3KFe6BL8
Where the blue of the night
Meets the gold of the day
Someone waits for me
And the gold of her hair
Crowns the blue of her eyes
Like a halo, tenderly
If only I could see her
Oh how happy I would be
Where the blue of the night
Meets the gold of the day
Someone waits for me
Here is Bing doing it from a film, but there is 2 minutes of talking before he starts singing:
http://www.youtube.com/watch?v=IRl-gMqyJLQ
Cheers, Tom.