Microweather In Car
Name: Klaus K.
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?
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.
Click here to return to the Weather Archives
Update: June 2012