Frost On Roof Above Freezing

Something i implied above but didn t say explicitly is that when frost forms on the roof the roof is below freezing.

Frost on roof above freezing.

That is how we get a frost without a freeze. Low temperatures overnight were generally in the. 2 the car roof cools radiatively. 1 initially the air and the car are at temperature 37 f and the dew point is 35.

Frost is a thin layer of ice on a solid surface which forms from water vapor in an above freezing atmosphere coming in contact with a solid surface whose temperature is below freezing and resulting in a phase change from water vapor a gas to ice a solid as the water vapor reaches the freezing point in temperate climates it most commonly appears on surfaces near the ground as fragile. The kentucky mesonet recently added some extra temperature sensors at varying heights that show just why this could occur. The plot below shows a 24 hour trace of the temperature measured at 0 5 meters above the ground in blue at 2 meters above the ground in red and at 3 meters above. We had a chilly start to the day with frost in many countryside locations.

Does your garage have a frosted roof and the rest of your home does not or vice versa. So how did ice form on the roof the frost on the car effect is not just due to temperature inversions. If the dew point is below freezing the water vapor condenses as ice freezing as frost. A lack of frost can indicate that heat is leaking out through your attic space onto the roof and melting the frost.

The radiative cooling effect is strong enough to lower the temperature of surfaces exposed to the sky by several degrees below the ambient air temperature. Look at the entirety of your roof is the frost melting unevenly and not due to the sun s heat. Something i implied above but didn t say explicitly is that when frost forms on the roof the roof is below freezing. In other words the sequence might be as follows.

The phenomenon of water freezing on objects like the ground parked cars motorbikes etc is due to thermal inertia. How can that be. Have you ever wondered why frost can form on nights when the temperatures only fall to 36 or 37 degrees. As it cools below 35 degrees water condenses on it.

So ice can form even if the temperature of the surrounding air is above freezing. 1 initially the air and the car are at temperature 37 f and the dew point is 35. In other words the sequence might be as follows. On a long cold spell these objects will cool down to below 0 celsius.