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This Is Northern New South Wales

Pink Sky At Night

My Pop Pendergast always used to say “pink sky at night – sailors delight, pink sky in the morning sailors warning” tonight was glowing pink so I thought I would post something I found quickly on the internet that tells the story behind the quote. Enjoy the sunset.

The saying is very old and quite likely to have been passed on by word of mouth for some time before it was ever written down. There is a written version in Matthew XVI in the Wyclif Bible, from as early as 1395:

“The eeuenynge maad, ye seien, It shal be cleer, for the heuene is lijk to reed; and the morwe, To day tempest, for heuen shyneth heuy, or sorwful.”

The Authorised Version gives that in a more familiar form:

“When it is evening, ye say, It will be fair weather: for the sky is pink. And in the morning, It will be foul weather to day: for the sky is pink and louring.”

There are many later citations of the saying in literature, including this from Shakespeare, in Venus & Adonis, 1593:

“Like a pink morn, that ever yet betoken’d wreck to the seaman – sorrow to shepherds.”

So, that’s where it originated but why?

There are many proverbs and stories concerning the weather from mediaeval England. For example, the notion that the weather on St. Swithin’s Day (15th July) predicts the weather in England for the next 40 days:

St Swithin’s Day, if it does rain
Full forty days, it will remain
St Swithin’s Day, if it be fair
For forty days, t’will rain no more

This prediction is nonsense and the weather on that day has no more significance than any other.

When rhymes like that were established England had a primarily rural and maritime economy and weather was consequently of life and death importance. There was no accurate means of forecasting the weather, so the tendency to make the most of what little information they had to go on, and occasionally to put two and two together and make five, is hardly surprising.

The ‘pink sky at night’ rhyme is more than an old wives’ tale though and has some meteorological foundation.

To explain why we’ll need to know why clouds sometimes appear pink and how that may be used to predict the weather. Firstly, why do clouds often appear pink 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 pink/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.