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What causes spectacular red and orange sunsets?

Few things make us stop to appreciate the natural world as much as a beautiful sunset.

A display of reds, oranges and pinks spreading across the evening sky can be a spectacular sight. But what makes this happen?

Sunset over Skye. (Image: Jonah Mael/Pixabay)

Speaking on Out of Doors, meteorologist Alex Hill explained how light travels from the sun through the atmosphere, resulting in the colourful sky.

Sunset, Banffshire (Image: Christine Webster)

“Blue light doesn’t travel particularly well through the air, which is why the sky is blue," he said. "It gets scattered across the top of the atmosphere."

As the day goes on, the lowering sun means that light has to travel further through the atmosphere than it does when the sun is at its height.

Alex continued: “The red light travels a lot easier. As the sun begins to go down you’ve got more and more atmosphere for the light from the sun to travel through.

"So what happens is the blue light kind of disappears and gets scattered all over the place and you’re left with a band of red light which hits the clouds.

"The cloud is higher up, so its sunset is a little bit later. So what you get then is the red light reflecting off the white clouds, and you get this strong red light coming down to you, sitting on the ground in the dark.”

Red sky at night, shepherd's delight?

A beautiful sunset often brings to mind the rhyme 'Red sky at night, shepherd's delight' which suggests good weather is on its way.

But Alex revealed that that's not quite the case.

"What you’re basically seeing is that for a few hundred miles to the west there isn’t any cloud because the sunlight’s getting through.

"Weather takes a while to get to you and if the weather is coming in from the west then you can probably reckon you’ve got 12 hours or so of fair weather. "

But, Alex said, we can't rely on the promises made by a red sky at night.

"[If] the weather’s coming from the north it won’t make the slightest bit of difference."

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