Frost on my windows on the highway in the summer?

[NathanS]

I was driving on the highway at about 110 Km/h (that is the speed limit) and my driver side windows started to frost up. Then my retreads fell off, I pulled over, changed the tire, the frost melted, and never came back. What was happening here?

 

[wviperw]

Probably a cloud/patch of fog you drove through. What was the temperature? And was it actual frost (as in frozen), or just fogged up windows?

 

[amdskip]

Sure it wasn't just fogged up windows?

 

[Mday]

how is this highly technical?

 

[Jeff7]

Well, it's not exactly similar....maybe, don't know. I put baking soda in a small disk of water, and it must have had something else in it, into the microwave, and zapped it for about a minute. (some popcorn had ignited itself, and we were trying to remove the smell from the lightly scorched interior) Well, I took the dish out, and it had a good crust of ice over it, and of course was quite cold. No idea what happened, and I'm fairly sure I wasn't going crazy.

 

[wviperw]

and I'm fairly sure I wasn't going crazy.

I think you better get that checked out... 😛

 

[dkozloski]

I had my RV sitting with the AC running full blast with very cold air being directed at the side windows. Outside the humidity was near 100%. Frost formed on the outside of the windows in the area of the airblast but quickly melted when I stared to move. In a similar manner my eyeglasses would fog-up when I stepped outside from the RV just like what happens when you go from the cold outside into a heated building in the winter.

 

[NathanS]

Well here (in Alberta) it is verry dry, and there was no fog, the AC was off. I thought maybe that the wind that was blowing by the vehicle was compressing verry fast and sort-of working like an Air conditioner works. and pulling the heat away from the vehicle. The frost was only down one side of the vehicle (the driver side) and it was *really* hot out so I have no clue as to what was going on. This is Highly Technical because there is a possability that in depth phisics could be happening.

 

[dxkj]

I would agree that frost forming on a window in summer heat would require a highly technical explanation.

If you didn't have any strange chemicals leaking from the car I am definitely interested in a possible explanation of this as well.

 

[dmw16]

Well, there is a local pressure drop around the surface of the car. You figure, atmospheric pressure is 1atm or 101.3Kpa. The density(rho) of air is ~1.23kg/m^3. So it goes like this:

Patm + 1/2(rho)V^2 + (rho)gh = Plocal + 1/2(rho)V^2 + (rho)gh

We cancel out the (rho)gh terms since there is no signifigant change in height. We take out the velocity term in the first half cuz it is considered to be well ahead of the stream. So V = 30.55m/s. We get 101.3e3 - .5*1.23*30.55^2 = 100427Pa. I dont think that was the cause of your frost as the pressure variance isnt all that extreme. Now, over curved surfaces, there can be a greater velocity variance, but to cause temps that low, it would have to be very extreme. So I think you can eliminate speed as an issue here.

So what exactly happen to your tire? You may have driven through some chemical that lowered temps on your car (if it splashed onto the windshield).
-doug

 

[NathanS]

I actually just re-treaded it too many times and it died. But as it was dieing the whole vehicle vibrated back and forth sideways.

 

[dkozloski]

I suspect that we are talking about condensation and not frost. All that would be required for moisture to condense on one side of the car is for the surface to be below the dewpoint. I have seen this many times myself because I have an unheated cinder block garage that is cool inside even on the hottest days. I back my car out of the garage on a hot humid day and the windows immediately fog up. To get the pressure changes required to get the surface of the vehicle below freezing would require a supersonic shock wave. Air cycling machines used to control the cabin environment in turbine aircraft can produce this kind of a temperature change but I can't begin to imagine a natural phenomenon that could duplicate this action. Maybe there was an alien abduction involved along with a popular recreational drug.