The colors of sunrise

The Barcelona Biomedical Research Park (PRBB) offers us privileged sea views every day. Today, through this photograph sent by Cristina Pujades (UPF), we analyse from an optics perspective the reason for these beautiful colors of the sunrise.

In the photo, you can see how the sky shows a palette of colors from pink or red to deep oranges and yellows.

If you’ve ever wondered why these are the colors of sunset and sunrise, it’s a matter of the scattering of sunlight. The atmosphere is a layer between the sun and the Earth. When the sun crosses it in a straight line (for example when we have the sun at its zenith, that is, just above our head), it goes through little atmosphere, and the light is able to reach us in a straight line in the same direction as it entered the atmosphere. But when the sun is in front of the horizon line (at sunrises and sunsets), the light arrives in an oblique direction. It then passes through much of the atmosphere, scattering short wavelengths, and only allowing long wavelengths (red, and other warm colors) to reach the surface in a straight line from which they were emitted.

Image from Metoffice

So, for a few minutes every day, we are lucky enough to enjoy an amazing light show from the PRBB, especially in the winter.

We thank Cristina Pujades for sharing this beautiful photo of the sunrise from the PRBB.

Want to see your photo here? Send us images related to science or life to the PRBB at

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