Astronomy Picture of the Day
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November 12, 1995
Blue Jet Lightning
Credit: D. Sentman, G. Wescott,
U. Alaska Fairbanks,
Recently two new types of lightning have
been verified: red sprites and
jets. These atmospheric discharges occur very high in the
Earth's atmosphere - much higher than the
familiar form of
appear blue in colour and go from the tops of clouds to a height of about 50
kilometres. Because blue jets typically last almost a full second,
one can easily see the jet rise from the clouds with a fast video camera.
Blue jets appear as narrow cones and travel about 100
kilometres per second. The existence of blue jets
has been suggested previously, but
only in 1994 were aircraft flown above
massive thunderstorms with the high speed video equipment necessary to
verify these spectacular events. The above black & white picture shows
several blue jets rising from a thunderstorm simultaneously. Part of the
aircraft is visible in silhouette on the right. Scientists are unsure of
the cause and nature of blue jets.
Tomorrow's picture: Virgo Cluster Galaxies
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