"Green Thunderstorms"
Green thunderstorms are observed occasionally, yet
have received
little scientific attention. Fraser suggested that
thunderstorms
are the dark backdrop for green airlight, a consequence
of reddened
sunlight illuminating selective scatterers. Bohren's
alternative
explanation is that green thunderstorms result
from the intrinsic
blueness of clouds because of selective absorption
by pure water.
Only the most massive clouds are thick enough to
shift the color of
incident sunlight upon transmission. If that incident
light is
reddened, the transmitted light can be perceptually
green. A field
program unerstaken with colleagues at the University
of Oklahoma
(Bill Beasley and Frank Gallagher) captured the
first spectra of
green thunderstorms, providing objective evidence
of their
existence. These spectra indicate that greenness
is not a sudden
turning on of a green lamp in the sky but rather
a subtle shift in
perceived color from blue to green. These measurements
also
indicate that contrary to reports of the "sky suddenly
turning
bright green", the shift from blue to green is
accompanied by a
reduction in luminance, as expected from both theories.
This seemingly
frivolous research attracted the ire of Newt Gingrich--and
look what
happened to him.