For the second day running there was a clear band of red sky towards the south in the afternoon. The sun was behind cloud at the top of the photograph. Now any colours we can see must be due to light coming directly towards our eye. Outside, the source of that light must be the sun. So light must be heading from the sun and then getting either reflected or absorbed and reemitted in our direction. Something must be happening to the sunlight to filter out the other colours. Normally, red sky and night and in the morning are due to dust in the direct line of sunlight filtering out the other colours. This is not in direct line. Maybe the clouds in the way are filtering colours. Mrs B suggested that it was maybe snow-laden clouds.
