In this image the surface temperature is higher, 27°F (-3°C). Also as elevation increases, the temperature increases to a point where some of the atmosphere is above freezing before the temperature lowers again to below freezing.

As snow falls into the layer of air where the temperature is above freezing, the snow flakes partially melt. As the precipitation reenters the air that is below freezing, the precipitation will re-freeze into ice pellets that bounce off the ground, commonly called sleet. The most likely place for freezing rain and sleet is to the north of warm fronts. The cause of the wintertime mess is a layer of air aloft that is above freezing.

 

Freezing rain will occur if the warm layer in the atmosphere is deep with only a shallow layer of air at the surface that is below freezing. The precipitation can begin as either rain and/or snow, but it all melts into rain in the warm layer. The rain falls back into air that is below freezing, but since the depth is shallow, the rain does not have time to freeze into sleet.

The rain freezes on contact when it hits the ground or objects such as bridges and vehicles that are at temperatures below 32 degrees Fahrenheit. Some of the most disastrous winter weather storms are due primarily to freezing rain.

 

 

Precipitation begins to fall as snow mixed in with some minor amounts of rain in this last image. Since the precipitation is falling toward the ground through a very deep layer of warm air, all of it is melted  or remains water (rain). With a temperature well above 32 degrees Fahrenheit at the ground, the precipitation stays in liquid form and hits the ground as rain.