Rainbows | Blue Sky | Sunrise & Sunset | Activity

Blue Sky

To understand why the sky is blue, we need to understand what light and color are all about!

Sunlight, or visible light, is white but it is made of all the rainbow colors: red, orange, yellow, green, blue, indigo, and violet. Visible light travels in waves. The waves are too small and travel too quickly for us to see. Colors like red, orange and yellow travel in longer waves and have less energy. Colors like blue, indigo and violet travel in shorter waves and have more energy. When waves of light are moving along and run into some type of matter, they can transfer some energy and certain types of light waves can be scattered.

Earth's atmosphere contains molecules of gas, mostly nitrogen and oxygen, as well as smaller amounts of carbon dioxide, aerosols, dust, and ozone. These particles scatter some waves of light more easily than others. The shorter waves, such as violet and blue, are the most likely to be scattered. The sky is blue because our eyes are not very sensitive to the violet light that is scattered.

(Left: NOAA, Right: L.Gardiner)