When melting snow-crystals or raindrops fall through very cold air, they freeze to form small particles of ice, called sleet.

VOA: special.2011.01.11

And it's dangerous. People slip and fall on the snow because it's made of ice.

这样也很危险，人们会在雪上滑倒，因为雪里面都是冰。

I'm glad 实战 - SpeakingMax英语口语达人

Shipping in the upper Great Lakes mostly stops in late fall because of ice.

VOA: special.2009.11.11