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Colored Lightning
Name: Johny
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: N/A
Question:
Ten years ago while I was living in Ajijic, Mexico
I witnessed lightning flashes in three colors, red, green, and
blue. Ajijic is at five thousand feet altitude and I was living in
a house higher up in the surrounding mountains. I had just gone to
bed, around ten or so as a thunder storm came in and I noticed the
strange colors. I got back up and watched this truly wonderful
colorful display which lasted thirty to forty minutes. I was at the
same altitude as the rain clouds so it was like being in the middle
of the storm. The colors were vividly bright and very
distinct. The green I could understand as possibly reflection from
the green foliage, the blue as possible reflection from the night
sky, but the red I have no guess as to its origin. I have never
heard or read anyone else describe colored lightning. Is this a
known phenomenon or did I witness something truly unusual?
Replies:
Johny,
From what you have written, it was apparently raining
and it was dark. It sounds as though there was a great deal
of pollution as well, and your position well above the
valley would have put you near the top of the daytime
atmospheric inversion, where the concentration of
pollutants is greatest. At night, there is no solar radiation
to obscure weak colors that may have been displayed
from the lightning, so that certainly helped you to see
the colors.
Normally, during daytime, severe thunderstorms exhibit
a green color as water vapor and droplets absorb the red
wavelengths of sunlight and aerosols (pollutants, particulates)
scatter out some of the blue wavelengths of sunlight. The night
that you saw the lightning, the rain and high water vapor content
of the air probably absorbed the red wavelengths of light from
the lightning, plus aerosols (pollutants, particulates) scattered
out some of the blue wavelengths of light to produce the green
color of lightning. At other times (during lighter or no rain
perhaps), the red wavelengths were prevalent because the aerosols
were scattering out all of the yellow and blue wavelengths (similar
to a red sunset on a polluted day). At still other times the
rain and high water vapor content of the air probably absorbed
the red wavelengths of light from the lightning and yellow
wavelengths were scattered out by the aerosols, leaving mostly
blue light. Furthermore, the presence of high concentrations of
ozone (a likelihood if it had been a polluted day) and terpenes
(produced by trees on the surrounding mountains) would also tend
to make the lightning look blue (similar to the blue tinge that
you see in the Blue Ridge mountains when ozone concentrations
are high).
You saw different colors from the lightning, depending on what
was in the path (rain, water vapor, ozone, aerosols, etc.) between
you and the lightning, and being where you were on the mountainside
and at an elevation above the valley floor enhanced the likelihood
that you would see such a display. Your eyes are also very sensitive
to colors from a light placed against a dark background, so that
probably helped to enhance the experience.
David R. Cook
Climate Research Section
Environmental Science Division
Argonne National Laboratory
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Update: June 2012
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