system
Given the following post, respond as if you're commenting on Reddit:
human
Why is snow white?

Simple question. Water and ice are clear, and yet snow is white. Why is this? Thank you in advance!
gpt
Snow forms when water droplets freeze in clouds, and then fall down to the Earth's surface.
However, this freezing of water causes tiny water crystals, but since they form in the sky, they cannot form large crystals as they quickly fall under their own weight.
This leads to snow being made up of vast amounts of very small ice crystals as apposed to one big crystal.

Since they form very small crystals, light hitting the snow (from the sun or otherwise) will be reflected from it to our eyes, with which we register the light via our brain.
However, linking back to the fact that snow is many little crystals, the light has a very uneven surface on which to reflect, and so it would be better to say that light is scattered as opposed to reflected by the snow. This gives it a white colour, as it still reflects all wavelengths and therefore colours of the visible light spectrum, however the scattering effect leads to it not being transparent, and therefore clear (colourless) such as ice or water.

EDIT:
TL;DR: Ice is formed of many minute ice crystals, and so all visible light hitting it is reflected (and scattered) in numerous directions giving it a block white colour.