Look up! Just do it. What do you see? Stupid question, eh? You see
ceiling of course. When you look upwards during a sunny day while picnicking however, you see blue sky. Ever wondered why sky is not green nor but blue?Before answering this question, let’s go back to basic physics of light. Sorry, but here I go…
Light is a kind of energy, which travels in waves. In fact, light is a wave of vibrating electric and magnetic fields. Light forms only one small part of a larger range of vibrating electromagnetic fields called electromagnetic spectrum. Electromagnetic waves travel through space at an amazing 300 00km/s. Therefore this is also speed of light.
When you see white light from bulb, you are actually seeing seven colours of rainbow! This is because white light consists of a combination of these seven colours.
Each of these colours has a different wavelength, frequency and energy. Wavelength is distance between crests of waves. The frequency is number of waves that pass by each second. Note that longer wavelength, lower frequency and less energy it contains.
·Violet: Shortest wavelength, highest frequency and energy ·Red: Longest wavelength, lowest frequency and energy
Now back to our main topic. That blue colour of sky is due to an effect known as Rayleigh scattering. As light from sun moves towards Earth’s atmosphere, not all colours are actually able to pass through that atmosphere. Most of longer wavelength colours do pass (red, orange and yellow for sure) but shorter wavelength ones however are mostly absorbed by gas molecules found in atmosphere. Absorbed blue light is then bounced back (radiated would be a better word) in all directions. This makes shy to appear blue!
