FORT WAYNE, Ind. (WFFT) — As it turns colder (again), the potential for frost creeps back into the picture.
Sometimes frost can form on a car but there isn’t any on the ground and sometimes the opposite happens where frost is on the ground but not on your car.
But, why is that?
Where frost develops depends on the objects temperatures and/or humidity(moisture) level.
Frost can form when the air temperature is below 32 degrees and the ground temperature is freezing.
The temperature that you see on TV or on your phone is actually measured a few feet above the ground and the coldest air is sitting at the surface.
Cold air is more dense which is why it is typically found on the ground or on grassy surfaces.
If the surface temperature is sitting at 32 degrees, frost can still form if the air temperature is 34 degrees.
Another factor is that grass holds moisture which can help frost form.
Freedom Park. You can see frost on the grass. It’s chilly out here.
— Blaine Tolison (@BTolisonWSOC9) January 15, 2021
The burning question might be, but why is there frost on my car and not the grass.
Materials such as metal and glass actually cool down more efficiently than other materials.
For instance, if your car is outside during the day, it’ll heat up under the sun along with the ground.
Once the sun goes down, the car is made of materials that release heat more quickly.
So the windshield and metal could drop to 32 degrees or colder faster than the ground and air around it.
— Matt Taylor (@MetMattTaylor) January 22, 2021
This is why you may see frost on the windshield and nothing on the ground if the air temperature is above freezing.
So why doesn’t frost form on the road or sidewalks?
That also boils down to the fact that concrete holds heat better due to the material it is made of and it cannot hold moisture.