How frost forms

INDIANAPOLIS (WISH) — Colder air is going to move into central Indiana this weekend. It looks like frost is a big possibility.

First let’s go over how frost forms. During the day the sun heats up the Earth during the day. Highs climb into the 40s, 50s 60s etc.

Once we get into the nighttime hours the air just above the surface cools. The cooling forces moisture onto the ground what we call dew.

Once temperatures fall below freezing the moisture freeze and frost forms.

We can technically get frost to form even though the temperatures on your smart phone app or the TV shows temperatures above freezing. This is because the temperatures are actually measured about five to six feet off the ground.

The air above the surface takes longer to cool down. The surface cools first and faster. So if the air temperature is 33 to 35 degrees the surface temperatures can actually dip below freezing and create frost.

If you did do some planting within the last week make sure you either bring those plants inside the garage or cover them up late Friday night and Saturday morning. Some spots may fall into the upper 20s if the conditions are right.