Why is “red sky at night” such a reliable thing?

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The old adage “red sky at night, sailors delight. Red sky in the morning, sailors take warning” seems to reasonably portend the weather forecast over the next 24 hours. Is there meteorological basis for this?

In: Planetary Science

2 Answers

Anonymous 0 Comments

The (possibly apocryphal) explanation I’ve heard is that the winds most relevant for sailors (trade winds, maybe?) blow primarily West to East, so if the evening sky is red, it means sunset light is being scattered into a clear sky, and that clear sky is headed your way (sunset being west of you). This seems like one of those correlations that was probably true for certain sailing routes and spread into wider culture where it probably should not be universal.

Anonymous 0 Comments

Red sky in the morning means a low pressure system is on the way. Red sky in the evening means the low pressure system has passed and clear weather is to be expected.