Sleet is a type of precipitation that occurs when raindrops freeze into ice pellets before reaching the ground. This usually happens when warm air is above and cold air is below, causing the rain to freeze as it falls. Sleet can create slippery surfaces, making travel hazardous. Sleet is often confused with hail, but they are different. Hail forms in thunderstorms and is larger, while sleet is smaller and falls during winter weather. Sleet can also be part of a winter storm, along with snow and freezing rain, affecting road conditions and visibility.