Why does ice not form on my car when I park it in a uninsulated garage?

Answer 1

Assuming your garage is not heated or air conditioned, then once you open the door to drive in, the interior atmosphere comes close to the exterior atmosphere. That is the humidity and temperature are approximately the same.

Now you can cool the car down as the nightime temperature decreases, but in the garage the car is not exposed to the night sky. Heat can be transfered by three methods. Convection, conduction, and radiation. The first two are the same methods by which heat is transferred in an oven to a pan.

Radiation heat transfer does not depend upon movement of air across the surface, or the difference in temperature. Instead it depends upon light or the lack of light. And this means both visible and nonvisible light frequencies.

The night sky is dark and actually absorbs energy due to its lack of light. This known as black body radiation. You are probably familiar with the reverse effect when you wear a black shirt on a sunny day. The shirt gets hot, because it absorbs the radiant heat from the sun. The same thing applies in reverse to the night sky. Another demnostration of radiant heat transfer is you will find that it is colder in winter when the sky is clear as opposed to cloudy. The clouds prevent the black body radiation from transferring heat from the atmosphere to the night sky.

You can find out more by doing a yahoo search on "black body radiation"

http://en.wikipedia.org/wiki/Black_body_radiation

Answer 2

Others have made good points, but they've missed an important thing. When the car is outside, it faces the sky. The car transfers heat to the sky through radiation. On a clear night, the sky temperature is very, very low. (Item 25 at http://research.me.udel.edu/advani/teaching/s98_me302_review.htm suggests -45C, way, way below freezing) This causes ice to form on my car when the temperature outside is well above freezing.

When the car is inside, it faces the ceiling of the garage, which is not much cooler (and perhaps warmer) than the outside air. Combine this with other people's suggestions about moisture content in the air, etc. and you have a working answer.

Answer 3

Because your uninsulated garage is still warm enough for ice not to form. Your house loses heat into the garage. And your garage might not have enough humidity too?

Answer 4

It could be that the garage retains enough of the heat that bleads out of the house. More likely, it is a function of your garage being too dry to allow for frost formation. You could test this by spraying your windshield with a mist before you go to bed. If it is still liquid in the morning, it is not getting below freezing.

Answer 5

Because it's drier in your garage than outside. For ice to form, it needs more than just the cold air, it needs water particles, which are much more prevalent outside then in the garage, especially if the garage door is closed.

Answer 6

you need a source of moisture and the most common source is from plants. in a garage, you typically have less moisture in the air. plus the garage will keep some residual heat and help keep frost or ice from forming on your car.

Answer 7

Because it's indoors and if the doors are closed ice wont form. Big temperature differences make for ice. Warmth inside, and cold outside {t=c(o)+w(i)=p} that formula represtents it. that happens outside. inside temperature can equalize, so no frost is made.

Answer 8

The roof slows or stops convection currents, it's the same idea as a greenhouse. If the warm air can't get out, or is slowed, the cold air can't get in.

All you have then is heat loss by radiation, which is less effective.

Answer 9

There is no water to form ice. It might be cold enough but you need lots of humidity too.

Answer 10

Less moisture & more warmth and no chilling breeze