January 20, 2006
rained all day when the temperature was freezing or about a degree
below freezing. The rain freezes on any surface on which it lands
- often the rain is supercooled and freezes very quickly upon contact
with solid surfaces. As can be seen from the spokes of my
garden windmill taken in the late afternoon, the ice had accumulated
about 1/4 inch all the way around the spokes. The ice storm had
started about midnight the previous night. By morning the
bearing had frozen and ceased to spin, even though the wind continued
all day. Because the windmill was not spinning, the icicles that
formed around the perimeter were affected by gravity and dripped
down. Compare with the centrifugal icicles from previous
years. Luckily this ice storm did minimal damage in the
Wilson Area. However, neighboring Henderson County in North
Carolina suffered major damage to power lines where many costumers were
without power for about 5 days.
I'm inspired to publish this photo primarily by the question posed by
Dr. Vicki Garlock. She asks "With the wind coming from one
direction, why does the ice build up evenly on all sides of small twigs
and wires?". Click here for the
answer as best I can describe it.
the morning, soon after
the windmill's bearings froze, remnants of
centrifugal icicles could be seen in the photo at right. Much
better centrifugal icicles may be seen in previous
years' ice storms.
Donald F. Collins
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