Sprites, Blue Jets and Gigantic Jets

Sprites are large-scale electrical discharges that occur high above thunderstorm clouds, or cumulonimbus, giving rise to a quite varied range of visual shapes flickering in the night sky. They are triggered by the discharges of positive lightning between an underlying thundercloud and the ground. They are a type of electrical phenomena called transient luminous events (TLEs) that occur high in the atmosphere. They are rarely observed visually and not well understood. They can extend up to 90 km’s from the cloud top. Sprites are mostly red and usually last no more than a few seconds, and their shapes are described as resembling jellyfish, carrots, or columns. Because sprites are not very bright, they can only be seen at night. They are rarely seen with the human eye, so they are most often imaged with highly sensitive cameras.

They often occur in clusters within the atmosphere above the troposphere at an altitude range of 50–90 km (31–56 mi).

Diag. Credit: Abestrobi  CC BY-SA 3.0  via Wikimedia Commons

The following photo was taken in South East Queensland by Australian photographer and storm chaser Grant Rolph.

Sprite by Grant Rolph on 500px.comImage Credit: Grant Rolph, used with permission. You can see more of Grant’s weather photography here.

Elves are rapidly expanding disk-shaped regions of glowing that can be up to 460 km’s (300 miles) across. They last less than a thousandth of a second, and occur above areas of active cloud to ground lightning. Scientists believe elves result when an energetic electromagnetic pulse extends up into the ionosphere.

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Blue Jets
Blue jets differ from sprites in that they project from the top of the cumulonimbus above a thunderstorm, typically in a narrow cone, to the lowest levels of the ionosphere 40 to 50 km (25 to 30 miles) above the earth. In addition, whereas red sprites tend to be associated with significant lightning strikes, blue jets do not appear to be directly triggered by lightning (they do, however, appear to relate to strong hail activity in thunderstorms). They are also brighter than sprites and, as implied by their name, are blue in colour. The colour is believed to be due to a set of blue and near-ultraviolet emission lines from neutral and ionized molecular nitrogen. Blue jets and gigantic jets are both forms of upper-atmospheric lightning or ionospheric lightning.

Photo Credit: Elka Liot & Muscapix Gregory Moulard

Gigantic Jets
Even rarer than blue jets, gigantic jets take place between clouds and the ionosphere where the electric potential is hundreds of kilovolts higher than earth’s surface. They are extremely powerful and while a typical lightning strike may travel less than ten kilometres, gigantic jets have been observed to shoot vertically up for more than 70 km.

Although their physics is not fully understood, researchers believe that gigantic jets could be a “missing link” in the Earth’s “global electric circuit” that helps maintain the potential difference of about 300,000 volts between the Earth’s surface and the ionosphere.

On August 13, 2016, photographer Phebe Pan caught a spectacularly clear wide-angle photo of a gigantic jet on a wide-angle lens while shooting Perseid meteors atop Shi Keng Kong peak in Guangdong province

Photo credit: Phebe Pan

The following photo was captured by my friend and fellow storm chaser Jeff Miles. Taken near a small town in the Pilbara region of Western Australia on Tuesday the 28th of March 2017, Jeff managed to capture a number of photos showing gigantic jets. You can check them out at his photography page here.

Photo credit: Jeff Miles / Snappermiles Photography . Used here with permission.

This article uses material from the Wikipedia 
article Upper-atmospheric Lightning which is released under 
the Creative Commons Attribution-Share-Alike License 3.0 and 
the NOAA National Severe Storms Laboratory with permission.

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