Why Does Frost Not Form on a Vehicle under a Carport?

carport frostIf you live in an area that experiences cold winters and park outside, you probably often go out in the morning and find your car covered with frost. If you don’t like the chore of cleaning your car in the morning before heading out for the day, the best way to protect it is to park it in a garage. If that is not an option, a carport is a good alternative. Even though it is open on the sides, a carport can keep your car free of frost.

Warm objects, such as vehicles, radiate heat. The warmer an object is, the more heat it loses. The ground loses heat on a cold night very quickly. Once the ground gets below the frost point of the air, water in the air condenses onto it and forms frost. This continues until all the water in the air condenses.

A carport reduces the rate at which the ground and a vehicle lose heat that they have generated or stored from the sun during the day. The top of a carport cools down at night, but it is still warmer than the sky, so the roof continues to radiate heat down into the carport and toward the ground. This increases the temperature under the carport and keeps it slightly warmer than other areas outside it. When the night turns cold, moisture in the air will condense and frost will form on the outside of the carport, but not under it on a vehicle.

A carport also creates a physical barrier that prevents moisture from condensing on the vehicle, even though the exterior of the vehicle is cold. This causes water in the atmosphere to condense on the outside of the carport on a clear night.

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