The science behind freezing rain

MINNEAPOLIS – Our meteorologists talk a lot about dense, cold air and the warm air flowing over it, but what is the actual science behind how freezing rain forms?

Thanks to John Zeigler of KARE 11, the non-scientists among us now have a better idea.

According to Zeigler, it all starts with a cold air mass.

It is very cold and dense, so warm air merges with cold air – or a warm front is created. This warm air rises and flows over the cold air, pushing the warm air upwards because this cold air is in turn dense. Then the warm air actually begins to cool down and moisture is created as it rises.

This moisture then condenses and forms clouds. And if we have clouds, there may be precipitation.

So what happens to this precipitation with this warm air mass?

Let’s say it’s 35 degrees in the cloud – then you have a real drop of water and not a snowflake. The difference between sleet and freezing rain is small, but it depends on the depth of the warm layer and how long it is cold.

If there is more cold air in this crevice, there will be sleet. If it’s just a tiny bit of cold air, it will be freezing rain.