Rainbow minus the rain and inside the house?
It’s not every morning that you wake up to see a rainbow on your celing, unless of course you left the lights on and the water tank had sprung a leak. At first I thought I had been painting in my sleep, but that was thankfully not the case. The apparent rainbow would fade and come back again, but would always come back in the same place which appeared to curve around the light fitting. The morning sun in Central England was at just the right angle to peep in through the blind and refract off a bunch of CD’s that were on my windowsill. Here are some photos of the rare and captivating event, only possible because of an unlikely and chance arrangment of objects.
The effect was a simulated rainbow and CD’s tend to bend white light, in this case from the sun, and break it down into the fundamental colours or show the visible light spectrum, very much like a fine raindrop or prisim would do. I had been trying to create some CD’s the night before, the product as ever lots of wasted discs, so I left them on the window sill, I had also proped the blind open a little bit to let some air come into the room. Try it for yourself, but I bet I couldn’t make it happen again if I tried.
Here comes the science bit :
“A compact disc (CD) also has thousands of microscopic grooves; therefore, you can use it as a simple type of spectroscope to analyze light.” read more see a diagram. Light is a tiny part of the Electromagnetic Spectrum, we have visible and invisible light and a rainbow is a display of only the visible light broken down. At one end of the invisible light spectrum we have Infra Red, and at the other end we have Ultra Violet.
The sky is blue because the air refracts only the blue part of the visible spectrum, this is the reason why the sky on Mars is not like our own, but as the sunsets or rises on Earth white light is refracted at different angles leading to green, red and beautiful purple skies. Earth clouds are usually white or grey because they refract all parts of the light spectrum at once. Certainly a strange arrangement of colour, next time you see a rainbow bear this in mind and try simulating your very own dry rainbow for yourself!