What factors determine if precipitation falls as freezing rain or sleet?

The key factors determining whether precipitation falls as freezing rain or sleet are temperature profiles within the atmosphere and the ground. Freezing rain occurs when warm air aloft melts snowflakes into liquid rain, which then freezes upon contact with cold surfaces near the ground. In contrast, sleet forms when precipitation falls through a layer of warm air that melts it into rain, but then passes through a colder layer before reaching the ground, refreezing into ice pellets. The thickness and temperature of these layers are crucial in determining the type of frozen precipitation.