Snow appears white due to how light interacts with the ice crystals. The color "white" isn't a substance that "goes" anywhere; rather, the
appearance changes when the physical structure of the ice is altered through melting.
Here is a breakdown of the process:
- Structure of Snow: A snowflake is a complex, intricate crystal composed of a network of ice and air pockets [1].
- Light Scattering: When sunlight (which contains all colors of the rainbow) hits this intricate structure, it is scattered and reflected in all directions by the many surfaces of the ice crystals and the air pockets within and between them [1, 2].
- Perception of White: Because all visible wavelengths of light are scattered roughly equally, our eyes perceive this mixture as white [1, 2]. The same principle makes things like salt, sugar, and foam appear white, even though the individual components are clear [2].
- Melting Process: When snow melts, the ordered structure of the ice crystals breaks down into individual water molecules that flow together to form a liquid mass [1, 2].
- Change in Appearance: In liquid water, there are no longer the numerous air pockets and crystal surfaces to scatter light in the same way. The light mostly passes straight through the water, making it appear clear or transparent [1, 2].
Therefore, the "white color" doesn't go anywhere; the physical form that
causes the white appearance is simply no longer present [1].
Where does the white colour go when the snow melts?
Tim Hope, Norheimsund, Norway
- The colour we see as white is in fact the equal sum of all the colours in the spectrum. Snow appears white because it is a crystalline form of a colourless liquid (water). Although in microscopic close-up the crystals too are colourless, light is scattered from the crystal edges. Because this scattering is random, and all colours are scattered equally, the colours merge to give white light. When the snow melts, the light is no longer scattered in this way.
Tim Waterfield, Montreal, Canada
- Nowhere: it is not a pigment. The whiteness is caused by the scattering of light by snow, firn and ice crystals. Liquid water does not scatter light to the same degree (unless frothed by turbulence), though it can refract light and show up green or blue parts of the visible spectrum.
David Alexander, Amherst, Mass. USA
- It goes where the flame goes when your lighter runs on empty.
Robert P van Driel, Antwerp, Belgium
- The snow is only white because of its complex structure - it reflects the light about rather than letting it pass straight through like water does. It's like when a pane of glass (such as a car windscreen) becomes fractured and gets criss-crosses of white lines through it where the cracks run. If you melted the glass, it would be clear again, as would the snow.
Dan Norcott, Loughborough
