• Question: Why is it that pink sky in the evening, indicates a good day next?

    Asked by dizzyg12 to Simon, Susan on 22 Nov 2013.
    • Photo: Simon Langley-Evans

      Simon Langley-Evans answered on 22 Nov 2013:

      In Britain this saying usually has some truth in it. This is because most of the systems that affect our weather come in from the Atlantic ocean which is to the west. The sun sets to the west and as it sets it will give clues to what weather fronts may be coming in from the Atlantic. A red sky at sunset means high pressure is moving in and so the next day will usually be dry and pleasant.

    • Photo: Susan Skelton

      Susan Skelton answered on 22 Nov 2013:

      “Red sky at night, sailor’s delight,
      Red sky in the morning, sailor’s warning! ”

      I remember that saying! 🙂

      That rhyme is a rule of thumb for weather forecasting that was used by sailors and fishermen for over 2,000 years! By simply looking at the pink-ish glow of the morning or evening sky, they could predict whether or not there might be a storm coming which would cause them to have to take shelter on land.

      A red sky happens when the light from the sun bounces off particles in the air. When there are big clouds, the light bounces off all the water droplets that make up the clouds.

      Because the Earth is spinning, most of our weather travels towards us from the west and leaves towards the east. But the Sun rises in the east and sets in the west!

      A red-coloured sunrise (pink sky in the morning) is caused by the light from the rising sun (in the east) bouncing off water droplets in the clouds towards the east of us. These clouds didn’t reach us yet! Within a few hours those clouds will be overhead and probably raining on us!

      On the other hand, a pink sky in the evening is caused by the light from the setting sun (to the west of us) bouncing off water droplets in the clouds traveling away from us to the west of us. Those clouds have already passed us, so hopefully the next day will be dry and sunny!

      This is observed all over the world, in both the northern and southern halves of the Earth.

      Sometimes a storm system might rain itself out before reaching us (who had seen the pink sky in the morning). But for ships at sea, the wind and rough seas from an approaching storm system would have still been a problem, even without rainfall, so this saying was probably a life-saver for many sailors over the years!

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