As the shepherds warn us, a red sky in the morning is not a good sign.
We often see a notably red sky in the morning when early sun shines from a clear eastern sky onto a much cloudy sky nearer us. A dramatic effect, like the one seen at sunrise above, is the result of this light bouncing off a line of frontal clouds. And fronts bring bad weather.
The red colour is not the clue here. We always see more reds, oranges and yellows at the start and end of the day. This is because the colours at the other end of the spectrum, blues, greens etc., are filtered out by the longer journey through our atmosphere when the sun is low.
The clue comes because a dramatic red colour is the result of the sun’s light bouncing back down from the clouds between the horizon and our location.
This saying is less dependable than Red Sky at Night, where the sunset indicates clear skies in the direction most our weather comes from – the west. But it can be useful.
For more on this and dozens of other weather signs and clues, see the main page on weather lore.