It’s not just because of the weather. The sky is grey in winter because of how the atmosphere works.
The sun is much fainter in winter than in summer, so it takes more sunlight to warm up the Earth’s surface. But because it’s colder outside, the air is less dense and can’t hold as much heat as warm air can.
In winter, even though we have less sunlight than in summer, there’s still enough to heat up Earth’s surface — but not enough to warm up the air above it. So instead of heating up, it escapes into space. This leaves us with a blue sky during the day and grey skies at night.
So why does it look blue during the day? Light from the sun has to travel all the way to the Earth’s surface, through our atmosphere and all its gases before reaching our eyes — this extra distance makes our sky appear blue!
Last modified: August 14, 2022