We see only the light that has not been scattered into other directions. The red wavelengths of sunlight that pass through the atmosphere without being scattered much reach our eyes, while the strongly scattered blue light does not.
The longer distance that the sunlight travels through the atmosphere when it is on the horizon amplifies the effect--there are more opportunities for blue light to be scattered than when the sun is overhead. Thus, the setting sun appears reddish. In a polluted sky, small aerosol particles of sulfate, organic carbon, or mineral dust further amplify the scattering of blue light, making sunsets in polluted conditions sometimes spectacular.
Clouds, on the other hand, are made of water droplets that are much larger than the wavelengths of visible light. The way they scatter sunlight is determined by how the light is refracted and internally reflected by, and diffracted around, the cloud droplets. For these particles the difference between the scattering of blue and red light is not nearly so large as it is for gas molecules.
Hence, our eyes receive substantial scattered light at all visible wavelengths, causing clouds to appear more white than blue, especially when viewed against a blue sky background. Since scattering by the atmosphere causes the sky to be blue, a planet with no atmosphere cannot have a bright sky. For example, photographs taken by the Apollo astronauts on the moon show them and the moon's surface bathed in sunlight, but a completely dark sky in all directions away from the sun.
Thanks for your comment, Aimen. Personally, I do think that too many people are looking at their phones when outdoors nowadays, or spend too much of their time indoors. Not to mention, many people seem to just regard the sky as always being there, and also not really regarding it as special? Thank you for your wonderful comment, Rachel.
Thank you, Kaih, for your comment clarifying the science. Thank you again! Thanks for your comment, Elizabeth! It is really beautiful, so we should definitely look up at the world around us and appreciate the sky more. I really enjoyed your picturesque blog post, Katie! I generally knew how the sky is blue, but how rainbows are seen is a new thing to me.
Great photos too! Do you think people nowadays are too busy looking at their phones or being indoors to appreciate the blue sky and rainbows? This was really interesting and also quite poetic to read. A very interesting article and good photos! I actually wondered why the sky was blue and your explanation is so easy to understand and it suddenly answers why the sky can be other colours.
Thank you for sharing the science and the photos! Wow Katie, I loved the photos! When light hits water, the water's molecules absorb some of the photons from the light.
Everything absorbs at a different wavelength Your green t-shirt absorbs red , and as a result reflects the remaining colours back at a viewer that's why your t-shirt looks green. In shallow bodies of water like a drinking glass light penetrates it completely, as there is not enough water to absorb enough photons, so we see the water as colourless.
In deeper waters however, not all the wavelengths of light can fully penetrate the liquid, as there are too many water molecules in the way of the photons. The water molecules absorb all the red wavelengths from the light, making it reflect blue.
Some light travels in short, "choppy" waves. Other light travels in long, lazy waves. Blue light waves are shorter than red light waves. All light travels in a straight line unless something gets in the way and does one of these things:—. Sunlight reaches Earth's atmosphere and is scattered in all directions by all the gases and particles in the air. Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves.
This is why we see a blue sky most of the time. Closer to the horizon, the sky fades to a lighter blue or white.
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