Solar Wind Sparks Lightning Strikes

Activity on the Sun sparks more lightning strikes on Earth, a new study suggests - knowledge that may make it possible to predict when these hazardous storms will hit.

Researchers found that when streams of high-speed solar particles strike the Earth's atmosphere, the average rate of lightning strikes increases by 32 percent in the months following the start of such activity.

Previous research had suggested that highly energetic cosmic rays were responsible for the lightning that lights up our skies, and that solar winds' magnetic fields in fact protected the Earth. But details in the journal Environmental Research Letters shows the opposite effect.

"We expected to see a decrease in lightning rates with the solar wind stream but what we actually saw was an enhancement. This caused us a bit of head-scratching," lead investigator Chris Scott, from the University of Reading, told The Guardian.

Scott notes that some 24,000 people are struck by lightning each year. With satellites closely monitoring solar activity, scientists may be able to forecast lightning storms before they hit as a sort of early warning system.

According to BBC News, as the Sun rotates, it hurls out these solar winds at over one million mph. These particles - mostly electrons and protons - can trigger the fascinating Northern Lights display, but have an effect on the weather as well.

The scientists found that when the speed and intensity of the solar winds increased, so did the rate of lightning strikes. And it lasts for over a month after they reach the atmosphere.

Compiling weather data from the UK Met Office's lightning detection system, Nasa's Advanced Composition Explorer and Geostationary Operational Environmental Satellites spacecraft, researchers found there was an average of 422 lightning strikes in the 40 days after the high-speed solar wind arrived, compared with 321 strikes in the 40 days prior.

The results suggest that the solar wind helps accelerate particles into our atmosphere rather than deflecting them, but the exact mechanism remains unknown.

"What we need to do now is to track these energetic particles down through the atmosphere, to see if we can see where they end up," Scott said.

Scott noted that solar winds can be predictable, making storm forecasting feasible.

We know the Sun rotates every 27 days, so there is a very strong recurrence rate. If we see them at one time, we know 27 days later it will be back again," he added.