One evening, Rhys Clark, neighbour of David Ladbrook (Member 61,512), spotted red-orange underbellies of Altocumulus clouds as he peered across the Thames Estuary from Old Leigh, Essex, England. Rhys’s view was a classic example of the proverb ‘red sky at night, sailor’s delight’ – an adage that is rooted in science.

As a general rule, places in the mid-latitudes (30- to 60-degrees latitude) experience prevailing winds from the west, known as the Westerlies. (For locations in the Northern Hemisphere like the British Isles, they have a southwesterly tilt.) The Westerlies and the jet stream associated with them drive weather systems from west to east, and they are one part of the scientific basis for the ‘red sky at night’ weather proverb.

The other is that unsettled weather in the mid-latitudes tends to pass over in systems of precipitation that are separated by gaps of calm. A Sun shining uninterrupted in the evening due to clear skies to the west suggests a gap in the weather is on its way. This is why it can light with golden and ruby hues the clouds overhead – presumably, the remnants of the last weather system that’s departing. Looking at the weather records for Rhys’s location the day following, we’re glad to confirm that conditions were fair.