Lighting in slow motion

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Lightning Reveals Its Power in Slow Motion



Tom Warner documents the powerful beauty of lightning with an array of optical and electromagnetic sensors. He often uses a Vision Research ‘Phantom’ high-speed camera.

Warner is a Ph.D student at the South Dakota School of Mines and Technology, in Rapid City. He studies atmospheric sciences with a specialty in lightning research. “Lightning is one of nature’s most spectacular phenomena,” says Warner. “I want to understand how lightning behaves.”

“Since 2007, I have used high-speed video cameras capable of recording lightning at up to 54,000 images per second. These cameras enable us to see lightning like never before, as we can clearly see lightning propagate downward from the clouds or upward from tall objects.

The camera continuously records in a looping memory buffer. “When I see a flash take place, I trigger the camera at the end of the flash and it saves the previous 2.5 seconds of video prior to the trigger.”

He then saves the video into the camera’s memory. It is then transferred to a computer hard drive to analyze later.

Warner explains what’s in each of these six videos, and how he made them.

Above:

Near Devil’s Tower, Wyoming

The video shows a downward-propagating negatively charged, stepped leader. The lightning branches out in many different directions, causing one leader to make a connection with the ground, creating a bright return stroke.

The lightning was filmed at 7,200 images per second (139 microseconds per image). The downward leaders are traveling at a couple of hundred kilometers per second. The bright return stroke travels upward at around half the speed of light, and is too fast to capture in more than one image.




Bear Butte, South Dakota

The video shows multiple, negative stepped leaders. The leaders travel in many different directions and periodically pause and redevelop. Eventually a negative stepped leader travels downward and reaches the ground, creating a return stroke.

Filmed at 7,200 images per second (139 microseconds per image).




Above the Clouds

This lightning, a negative stepped leader, was filmed from an airplane. A stepped leader forms a connection making a return stroke with a rapid re-brightening of the channel. A second brightening is caused by a fast, downward dart-leader. It travels down the same channel and causes a second return stroke. When seen in real time, it looks like flickering.

Filmed at 1,000 images per second (1 millisecond per image).




From the Clouds

Video shows a positive leader of lightning from a cloud. There is a return stroke after the lightning hits the ground. The positive leader is very dim and highly branched at first. A strobe effect appears along the dim branch channels. These are recoil leaders and actually travel back towards the clouds along the channel branches. This is a unique feature of positive-leader development — not seen optically, Warner notes, until the advent of high-speed cameras.

Filmed at 7,200 images per second.




Negative Lightning Hits Tower

This is a unique recording of a downward, negative stepped leader that makes a connection with a tower. As the negative stepped leader gets closer to the tower, a positive leader forms from the tower tip and moves upward. This upward leader connects with the downward leader and a return stroke occurs. Five more dart leader-return strokes follow.

Filmed at 7,200 images per second.




TV Tower Initiates Lightning Strike

This video shows a positively charged upward-propagating leader. It forms from the tip of a TV tower, then branches up to the cloud above. Some of the dim branches exhibit bright recoil leaders. The shape of the tower enhances its electric field, which in essence, initiates the lightning.



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