Red Sprites Observed Over Southern France

November 28, 2006

20060911_01

Provided and copyright by: Oscar van der Velde
Summary authors & editors: Oscar van der Velde

The curious photo above shows a rare color image of red sprites, which formed above a thunderstorm complex nearly 325 km (200 mi) distant and at altitudes of approximately 45-85 kilometers (28-53 mi). Sprites may occur when an exceptional amount of electric charge is "removed" from a thunderstorm by cloud-to-ground lightning strikes. The resulting change in the electric field above the storm seems to reach the breakdown threshold around 75 km (47 mi) height -- where streamers start to grow. Sprites only lasts a fraction of a second and are usually only produced during the mature to decaying stages of large storm complexes. Typically, during favorable conditions, a sprite may be generated every few minutes. The amazing sprites pictured above were also observed with the naked eye.

Photo details: Canon EOS 5D, ISO 1600, 50 mm, 4 seconds at f/1.8. Photo taken above Mont Aigoual, France, on September 11, 2006. The white dots are stars -- the constellations of Ophiuchus is to the left and Serpens Caput in center/right. I'm looking towards the west, where a storm was present southeast of Bordeaux (almost 325 km (200 mi) away. The Moon was behind me and made the sky look a bit blue. Note that the relative brightness of the sprite in the image is less than that of the stars because it occurred only during a fraction of the total exposure time. However, with my unaided eye, the perceived brightness of the sprites was greater than most of the stars visible in the picture.

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