Lightning on Earth may not only be triggered by cosmic rays from space, but also by energetic particles from the sun, according to a recent study The Guardian reported.

Researchers from the University of Reading in the United Kingdom found a link between increased thunderstorm activity on Earth and streams of high-energy particles accelerated by the solar wind, offering compelling evidence that particles from space help trigger lightning bolts.

They found a substantial and significant increase in lightning rates across Europe for up to 40 days after the arrival of high-speed solar winds, which can travel at more than a million miles per hour, into the Earth's atmosphere.

"Our main result is that we have found evidence that high-speed solar wind streams can increase lightning rates. This may be an actual increase in lightning or an increase in the magnitude of lightning, lifting it above the detection threshold of measurement instruments," Dr. Chris Scott, leader of the study, said in a statement. "Cosmic rays, tiny particles from across the Universe accelerated to close to the speed of light by exploding stars, have been thought to play a part in thundery weather down on Earth, but our work provides new evidence that similar, if lower energy, particles created by our own Sun also affect lightning."

For the study, researchers analyzed data from NASA's Advanced Composition Explorer spacecraft, which lies between the Sun and the Earth and measures the characteristics of solar winds. The record of lightning strikes was compared with data from NASA's Advanced Composition Explorer (ACE) spacecraft, which lies between the Sun and the Earth and measures the characteristics of solar winds.

The solar wind consists of a constant stream of energetic particles-mainly electrons and protons-that are propelled from the Sun's atmosphere at around a million miles per hour.

Their research showed there was an average of 422 lightning strikes across the United Kingdom in the following 40 days, compared to an average of 321 lightning strikes in the 40 days prior the arrival of the solar wind. The rate of lightning strikes peaked between 12 and 18 days after the arrival of the solar wind.

The findings were recently published in the journal Environmental Research Letters.