We know enough about lightning to be in awe of it. We know a strong strike can impart over a million volts of electricity and heat the air around it up to four times hotter than the Sun’s surface, but we have no idea how it starts. New research may have the answer.
Publishing in the journal Environmental Research Letters, scientists from the University of Reading have correlated high-energy particles screaming from the Sun with increased rates of lightning. Their new paper is the latest attempt to explain how million-volt bolts begin.
Like a spark plug in your car, lightning starts when electricity jumps through the air. Air is a poor conductor, so it takes a huge voltage to bridge the gap from cloud to ground. Your spark plugs produce around 20,000 volts to cross the small gap in your car. A lightning bolt sometimes crosses miles. Lightning jumps so far in fact that scientists haven’t been able to explain what starts the bolt—even the massive voltage involved isn’t enough to cross that much air.
The conventional wisdom is that cosmic rays—bursts of energetic particles from distant supernovae and other cosmic calamities—have something to do with it. Those particles certainly have enough energy to enter our atmosphere and they may prime the atmosphere for electric discharges. But this new paper suggests that lower energy particles that the Sun is constantly emitting can also have an effect.
Looking at lightning strikes occurring within 500 kilometers of central England between 2004 and 2005, lead author Dr. Chris Scott and his team found that lightning strikes were more prevalent in the 40 days following the arrival of a strong bout of solar wind. These particles could carve a path through the upper atmosphere and start lightning.
We already know that solar wind interacts with our atmosphere in astonishing ways. Aurorae—the gorgeous green and blue bands that slither near Earth’s poles—are a direct result from the channeling of solar particles through Earth’s magnetopshere. Creating lightning could be another of the Sun’s peculiarities.
However, the data is still correlational. The authors of the study do not offer a causal mechanism for how lightning actually starts. Particles from the solar wind could be working in tandem with cosmic rays, or causing lightning all by itself, or not at all. We still don’t know.
“We propose that these particles, while not having sufficient energies to reach the ground and be detected there, nevertheless electrify the atmosphere as they collide with it, altering the electrical properties of the air and thus influencing the rate or intensity at which lightning occurs,” said Dr Scott in a press release.
The authors also explained their findings in a video abstract below:
IMAGES: Lightning From Space by NASA, University of Reading