Physics Photo of the Week
December
14, 2007
Dew Drop Door
On one
morning in late summer this garage door showed these patters of dew
condensed
on the panels. Each panel spans the whole width of the door and
is about 2 feet high. Notice that each each panel has no
dew condensed on the edges nor on the selected vertical parts of each
panel. The dew is concentrated in the broad center
regions of each panel. This tells us a lot about the construction
of the door panels.
The main part of a door panel is thin aluminum. During the night,
the thin aluminum is able to cool appreciably to the environment's
temperature of the outdoors. Where there are beams
along the borders and down the middle
of each panel to reinforce the aluminum, the extra mass of the beams
takes a longer time to cool to the environment's temperature.
These larger mass regions
stay warm throughout the night - above the dew point
temperature. The dew condensate pattern can tell a detective
something about the internal construction of an object. A similar
thermal pattern is illustrated in the Feb.
2, 2006 PPOW.
Later in the day, the dew has evaporated and the door appears as
shown at right.
Physics
Photo of the
Week is
published weekly during the academic year on Fridays by the Warren
Wilson College Physics
Department. These photos feature an interesting phenomena in
the world around us. Students, faculty, and others are invited to
submit digital (or film) photographs for publication and
explanation. Atmospheric phenomena are especially welcome.
Please send any photos to dcollins@warren-wilson.edu.
Click
here to see the Physics Photo
of
the Week Archive.
Observers are invited to submit
digital photos to:
