If you have ever seen a sunrise or sunset then you can appreciate the beauty of seeing the sun peek over the horizon at 6 am or fall under the horizon at 6 pm. The peace and serenity of these moments allow us to see the sun in a whole new light then during the middle of the day. Sunrises and sunsets are characterized by seeing blazing red and orange colors filling the sky compared to the blue sky that we are so familiar with. Today we are going to explain why the sky in the early morning and evening is just so darn beautiful!
First off, let’s explain why the sky is normally blue in the first place. The sun produces the light that we see during the day, as the sun passes through our atmosphere it encounters many gasses that it bounces off of. In the electromagnetic spectrum of the visible light that we can see, think ROYGBIV, the colors span from red that has the longest wavelength to blue and violet which has the shortest wavelength. As the light that we see passes through our atmosphere blue light reflects off of the molecules of gas that fills our sky. Furthermore, when blue light is reflected it is then portrayed in the sky and produces the sky blue we see every day. Red light has a much longer wavelength and is thus able to pass right through the gasses. This phenomenon is called Rayleigh Scattering which also explains why the sun is yellow in our sky.
Now, how about the red color you get from sunrises and sunsets! Well in the middle of the day the path for the light to reach us is short and therefore only blue light is reflected and is seen. But at dawn and dusk the path for the light to travel is much longer and has to pass through much more air causing the blue light to be completely scattered. This allows red and orange light to make it through because of that large wavelength. If there are clouds on the horizon then you get an even more beautiful setting as they can reflect the red and orange light as well.
Another reason why you could get glorious sunrises and sunsets are from the presence of natural and manmade aerosols in the atmosphere. Aerosols are solid or liquid particles in the sky that come from natural sources such as forest fires or volcanic eruptions or from manmade sources like pollution. These aerosols provide for the very dramatic bright red sunrises and sunsets that one would see over a large city such as Los Angeles!
All in all, the phenomenon called Rayleigh Scattering is responsible for the beauty of the sky both the blue in the middle of the day and the red and orange at dawn and dusk. Natural and manmade aerosols are also responsible for brilliant sunsets and sunrises. Now all you have to do to enjoy these sunrises is to wake up early enough!
Sources:
https://www.scientificamerican.com/article/fact-or-fiction-smog-creates-beautiful-sunsets/
