Rare blue starter
photo: , Thomas Ashcraft
We all know what comes out of the bottom of thunderstorms: lightning bolts. But on Oct. 20th, Thomas Ashcraft of New Mexico saw something coming out of the top. "I captured a form of a transient luminous event called a 'blue starter' shooting up from the top of a thunderstorm cloud," he says. "Blue starters are rarely captured from ground level and there are hardly any specimens on the internet."
Lightning scientist Oscar van der Velde explains this phenomenon: "A blue starter is an electric streamer discharge coming out of the top of a thundercloud, fanning out and reaching up to the stratosphere as high as 26 km altitude. First reported by UAF scientists Wescott and Sentman in 1995/1996, they were found to be different fromblue jets, which reach 35-40 km height."
"Since then, there have been very few reports of blue starters," continues van der Velde. "It seems that unusual physical circumstances may be required to produce them. Also, geometry can prevent people from seeing blue starters when a cloud is nearby because the underbody of the cloud can block their view. At larger distances the blue/violet light does not make it to the observer due to scattering."
Blue starters and blue jets are cousins of sprites, another form of exotic lightning that shoots up instead of down. Sprites, however, are more frequently observed. Check them out in the realtime photo gallery:
Bron:http://www.spaceweather.com/ | Gewijzigd: 30 januari 2017, 14:07 uur, door Joyce.s
