Sunday, August 14

Bolt from the Blue

IMG 945 -- Bolt from the BlueOn this night, I had the rare luck of capturing a less photographed form of lightning called a 'bolt from the blue', so named since they shoot out from the top of the storm, arcing sideways-- around the anvil-- and touching ground far outside of the storm's main precipitation regions. While spectacular to photograph (but almost impossible to witness visually), such bolts are far more deadly than the common negatively-charged strike and the cause of many deaths as they carry tremendously greater charge (usually 10X more than the common bolt!), and thus travel several miles outside of the main storm body.

On the night of the 3rd, I had the rare luck of capturing a less frequently photographed form of lightning called a bolt from the blue.

Such super-bolts, while spectacular to witness and document, are absolutely lethal and destructive as they possess about 10X the charge of the more common negative bolt. Also referred to as dry lightning, they have caused many fatalities and millions of dollars in damage.

The visible lightning discharge (return stroke) originates within the storm's upper glaciated anvil which holds solid hydrometeors (ice crystals & hail/graupel) that carry positive charge.

The initial stepped leader sets off as an intracloud bolt within the positively charged upper anvil/tower region before traveling outward up to several miles then down towards an unsuspecting target on the negatively charged ground. Positive bolts are the most highly charged and long-lasting form of lightning. While the average common negative bolt carries enough energy to light a 10-watt bulb for 2 months, a positive bolt can release enough energy to light a 100-watt bulb for almost a century!!

Positive lightning strikes of this kind are superceded in rarity only by ball lightning, which I personally have yet to witness.

Captured with Canon 40D in northeast Colorado. Exposure time: 23 sec., ISO 100, Canon EF-S 10-22mm zoom.

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