Scientific+Evidence+&+Information

This page has scientific information about some of the weather lore the students have selected. Team Sunrays : Red sky at night, sailors delight, red sky in the morning, sailors take warning. The 'red sky at night' rhyme is more than an old wives' tale though and has some meteorological foundation - in England at least.

To explain why we'll need to know why clouds sometimes appear red and how that may be used to predict the weather. Firstly, why do clouds often appear red in the morning and evening?

- Sunlight is broken into the familiar rainbow spectrum of varying-wavelength colours as it passes through the atmosphere.

- The blue/violet end of the spectrum is diverted more than the red/orange.

(This is the same mechanism that causes us to see the sky as blue incidentally, but that's getting rather off our point)

- When the sun is low in the sky, at dawn and dusk, sunlight travels through more atmosphere than at other times of day. The red wavelength is better able to go on a direct course and be reflected back off clouds, whereas the blue light is more scattered before reaching the cloud and is therefore less visible. So, we see the clouds as red as the light that is reaching them is primarily red.