system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does some ice appear clear, whilst other ice appears frosty? What's the difference, and what causes said difference?
gpt
Air bubbles and the size of the crystals as the water freezes. If water is agitated as it freezes, or if it's frozen quickly, it'll form smaller, tighter crystals, and keeps bubbles of air from forming, which will leave it clear. If you want to have nice, pretty clear ice cubes, boil the water first.