Why would a lightning-struck tree glow after being hit?
It is not on fire and does not give off heat, but glows.
It was a dark and stormy night. Chris emails he
was walking in the woods "a little after a thunderstorm" when he
noticed the tree. The tree, shattered by an earlier lightning
stroke, stabbed the night like a broken pike. An eerie glow extended ...
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Curious sunrises
![[Lanney Atchley] Sun pillar, Sandia Park, New Mexico](2003-01-31-sun-pillar.jpg)
Q: There was a very curious sunrise this morning: a solid, vertical column of light ascending from the
just rising sun. I don't recall seeing anything like it before. Is this a marvel or merely a common
occurrence that I have until now missed? Lanney, Sandia Park, New Mexico
Sun pillar. Photo courtesy of Lanney Atchley.
A: It's a beautiful photo and the colored light is called a sun pillar. "Shafts of light that extend vertically from
the sun are called sun pillars," says Lynch and Livingston of Color and Light in Nature. They are most often
seen above the sun when the sun is low (1 to 2 degrees of the horizon). The pillars--as wide and the same color
as the sun--are similar to the reflection the setting sun makes on a body of water.
Ice crystals, drifting down like leaves, cause the phenomenon. The crystals must be aligned almost
horizontally--tipped slightly down. (Related: figures showing how ice forms a sun pillar.)
"These crystals fall in a wobbly way," says Bob McDavitt, MetService Weather Ambassador in Newton, Australia.
Sunlight grazes the
crystal bottoms and bounces down to your eye (if you're around). The
wobbly fall of the crystals smears the image out vertically. Light
seems to come from a vertical shaft instead of the actual stack of
reflections.
Nearby pillars that form
over streetlights in fog can vanish and reform almost instantly as a
gust of wind realigns the crystals. Immersed in
the diamond dust, you see an eerie three-dimensional effect.
How common? "It's like a
tree falling in the forest or an iceberg breaking off from a glacier.
Happening all the time, but not many of us
are watching," says McDavitt. It doesn't take much to produce a sun
pillar: setting or rising sun, a sky clear of low clouds but with
sufficient cirrus clouds for a bank of ice crystals to reflect
sunlight.
However, that depends on
geography says Keith C. Heidorn, The Weather Doctor. "In New Mexico,
they may be more rare due to lack
of moisture in the atmosphere and the small number of days with snow on
the ground."
Further Reading:
The Weather Doctor: Sun pillars
Sundog: Sun Pillar
(Answered Jan. 24, 2003; updated Sep. 8, 2007)
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