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Name: Klaus K.
Status: other
Grade: other
Location: CT
Country: N/A
Date: 1/9/2005


Question:
I recently experienced what I would describe as a micro weather phenomenon. When I opened a door or the trunk of my car a small snow flurry happened! A few flakes of snow seemed to be drawn out from inside the car. The first time I thought it was my eyes, brain, whatever. But it happened 3 or 4 times. Once some little flakes landed on my sleeve and they did seem to be snow or ice crystals. The temperature at the time was in the 20's and weather was clear. The car had been parked outdoors for two days without being opened. The car was last open when temperatures were in the 40's and there had been a light rain. Was this really snow being created by the air pressure drop from opening the door?


Replies:
Klaus,

My guess is that the humidity in the car was high from the day that it rained and when the temperature dropped, ice crystals formed, probably on the door or trunk lid. These broke away from whatever they were on that you moved, and floated out at you.

David R. Cook
Atmospheric Physics and Chemistry Section
Environmental Research Division
Argonne National Laboratory


The formation of ice crystals under the conditions you describe is not too surprising. The trunk contained warmer moist air from the rain at 40 F that condensed out in dry colder air at 20 F. It is the drop in temperature that produced the ice condensation, however, not a drop in pressure, because it is highly unlikely that the car trunk is air tight.

Vince Calder


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