Why do sunrises and sunsets on Earth appear so much more vibrant during winter?
Winter sunrises and sunsets appear more vibrant during the winter thanks to a combination of lower humidity, lack of air pollution and better clouds. The beautiful pink, red and orange hues that appear at dusk and dawn are created by Rayleigh scattering – the same phenomenon that makes the sky appear blue during the day. At sunset or sunrise, the Sun’s rays travel through a greater distance of atmosphere to reach our eyes, which filters out most of the shorter blue and violet wavelengths, along with some green and yellow. That leaves us with the warmer hues of the reds and oranges, leading to fiery-looking skies.
It’s a myth that dust and air pollution make sunsets more dramatic. Aerosol particles attract water vapour, scattering the light and reducing the spectral purity. That means a more subdued or muted palette in summer’s smog and haze.
But crisp winter air tends to be drier and cleaner, especially when it comes from the Arctic, allowing purer, brighter colours to reach our eyes.
Finally, a stronger jet stream in winter creates well-defined weather systems, with clouds that form a perfect backdrop for the setting Sun.
“It’s a myth that dust makes sunsets more dramatic”
Kirsty McCabe