All About Green Lightning

Green lightning is such a rare weather phenomenon that only a few are lucky enough to have witnessed. It’s almost like regular lightning, except for its eerie green color. There already is a simple theory behind it and some misconceptions as well.

The only actual photograph of green lightning was taken during the eruption of the Chaiten volcano in Chile, spewing out a cloud of ash toward the sky.

Volcanic ash typically carries lightning bolts, a phenomenon known as volcanic lightning, except this time, the plume of volcanic ash had an eerie green lightning bolt.

A scientist of Rice University, Arthur Few, seems to have solved why the green lighting was only seen there and not anywhere else.

First Sighting of Green Lightning

The Chaiten volcano in Chile violently erupted in May 2008, spewing clouds of ash and lighting the dark sky with an unusual type of lightning. Photographer Carlos Gutierrez photographed the dramatic nighttime display, capturing a bolt of green lightning emerging from the cloud of ash.

The reason behind the bright green lightning bolt stayed a mystery until Arthur Few, an atmospheric scientist from Rice University in Houston, grew curious about the phenomenon. Few said, “I thought, ‘That’s funny; why don’t we see this in lightning storms?'” at the American Geophysical Union’s meeting in San Francisco on a Monday.

However unusual green lightning seems to be, some now suspect it happens during thunderstorms, only concealed inside the clouds.

Secret Origins

The structure of the storm clouds causes the concealment of the green lightning. On the interior, the clouds hold ice crystals that are either negatively or positively charged. Electricity surges happen between the positively and negatively charged regions inside the clouds—lightning—but they stay within, not to be seen by even the most dedicated storm chasers. 

On the contrary, volcanic ash clouds have their electrical charges on the exterior, where fragments of rock forcibly ejected into the air throughout an eruption spark them.

Some think that the bright green bolts of lightning seen at the Chaiten volcano are just “positive streamers” —a channel of positively charged molecules attracted to a negatively charged region on the cloud’s exterior. When both channels meet, they complete the circuit and discharge energy.

The Green Hue Explained

Why is green lightning green? Few remarked that the electrically excited oxygen atoms give the lightning its green color—oxygen molecules are supercharged by the bolt’s energy, then lose the excess energy. He thinks that a similar process colors the sky green in the fantastic light displays of the aurora borealis, dominating northern skies during winter.

This phenomenon might have also painted the Comet Lovejoy’s tail as it moved overhead in November.

Is Green Lightning a Common Occurrence?

dark sky, lightning, storm clouds, field

Arthur Few stated that green lightning is more common than we think. We don’t notice it all the time due to it typically occurring inside the clour instead of outside.

As lightning hops from one region of a cloud to another, there may possibly be many green lightning streaks, but because of the ice crystals that cause the static charge buildup within the cloud, we don’t notice the lightning bolt.

It can be seen in the ash cloud due to the ash particles (the collide and produce static charge) are outside that cloud.

Arther Few insinuates that if we can see inside the clouds, we might see the green lightning more frequently.

Things That Resemble Green Lightning

Maybe not precisely like the green lightning, a similar phenomenon is a green flash, which sometimes happens during severe weather. This green flash is known to be a power arc.

A power arc occurs when a short circuit of a high voltage power line generates an arc of electricity. The arc only lasts for a few seconds, as most power lines contain a built-in safety mechanism to mitigate the damage from short circuits.

These shorts are bright and incredibly powerful and can include tens of thousands of amperes. These arcs can be colored green, turquoise, blue, and even orange, which is why lots of people report that the sky turned green.

Usually, this short turn off the power, meaning a green flash, is also correlated with a power loss in that particular area.

Sometimes, the arcs are addressed as “exploding transformers,” although transformers aren’t always responsible. A power arc can result from any simple short circuit, whether a wet branch linked two lines, a squirrel was unlucky enough to go across and connect the circuit, or the wind causes two power lines to meet.

If this phenomenon is a result of lightning, it’s known as a “flashover.” Flashovers happen when a lightning bolt joins two power lines or a well-grounded object and causes a very bright (sometimes as bright as lightning) flash of light that came from the ground and working up.