May 7, 2012
The photo above shows a seldom seen blue jet emanating from a distant thunderhead as observed over Elsie, Michigan. It’s the faint bluish jet or streak of light just above the black walnut tree (Juglans nigra) on the right side of the barn. I was photographing this lightning storm, which was probably about 30 mi (48 km) to the north of my home, in the early summer of 2008. At the time, I didn’t even realize what I had captured until going through my lightning archives a few months back. I recently contacted Dr. Walter Lyons at FMA Research who confirmed that this was indeed a rare ground capture of a blue jet — most observations are made from aircraft.
Blue jets are a type of high altitude lightning phenomenon, distinct from red sprites. These jets are optical ejections from the top of the electrically active core regions of thunderstorms — quite often severe storms. After emerging from the top of the storm, they’re observed to propagate upward in narrow cones of about 15 degrees and at velocities of roughly 100 km/s (Mach 300). They typically disappear from view at heights between about 65-80 mi (40-50 km).
The University of Alaska has a lot more about blue jets and red sprites, explaining that:
Red sprites and blue jets are upper atmospheric optical phenomena associated with thunderstorms that have only recently been documented using low light level television technology.
…Numerous images have also been obtained from aircraft of blue jets ( Wescott et al., 1995), also a previously unrecorded form of optical activity above thunderstorms. Blue jets appear to emerge directly from the tops of clouds and shoot upward in narrow cones through the stratosphere. Their upward speed has been measured to be about 100 km per second.
Anecdotal reports of “rocket-like” and other optical emissions above thunderstorms go back more than a century (Lyons, 1994), and there have been several pilot reports of similar phenomena (Vaughan and Vonnegut, 1989). Possibly associated gamma ray bursts and TIPPS have also recently reported. Together, these phenomena suggest that thunderstorms exert a much greater influence on the middle and upper atmospheres than was previously suspected.
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