Snow is a bunch of ice crystals stuck together. It’s a very complex arrangement. To understand why snow is white, we must be familiar with what happens to light when it strikes any material. The colour of anything, including snow, depends on how light interacts with it. Visible light consists of a rainbow of colours, the ROY G BIV colours of red, orange, yellow, green, blue, indigo, and violet that were assigned by Isaac Newton. When photons of light strike an object, they may bounce back (reflection), bounce to the sides (scattering), pass right through (transmission), or give up their energy (absorption). Grass is green because it reflects the green light to our eyes and absorbs all the other colours. Red apples reflect red light to our eyes and absorb the wavelengths of all the other colours.
When light goes into snow, it hits all those ice crystals and air pockets and bounces around, and then some of the light comes back out. Snow reflects all the colours; no it doesn’t absorb, transmit, or scatter any single colour or wavelength more than any other. The colour of all the light wavelengths combined equally is white. So all the colours coming out are the same colours that go in, combining to make white light.
Why is snow white, and where does its colour go when the snow melts?
Answers
Dilip Patel
Snow is a bunch of ice crystals stuck together. It’s a very complex arrangement. To understand why snow is white, we must be familiar with what happens to light when it strikes any material. The colour of anything, including snow, depends on how light interacts with it. Visible light consists of a rainbow of colours, the ROY G BIV colours of red, orange, yellow, green, blue, indigo, and violet that were assigned by Isaac Newton. When photons of light strike an object, they may bounce back (reflection), bounce to the sides (scattering), pass right through (transmission), or give up their energy (absorption). Grass is green because it reflects the green light to our eyes and absorbs all the other colours. Red apples reflect red light to our eyes and absorb the wavelengths of all the other colours.
When light goes into snow, it hits all those ice crystals and air pockets and bounces around, and then some of the light comes back out. Snow reflects all the colours; no it doesn’t absorb, transmit, or scatter any single colour or wavelength more than any other. The colour of all the light wavelengths combined equally is white. So all the colours coming out are the same colours that go in, combining to make white light.