The Sun plays a significant role in the generation of lightning strikes on Earth, according to a new study that found that over a 5-year period the United Kingdom experienced 50 percent more lightning strikes when the magnetic field of our planet was skewed by that of the Sun.
“We’ve discovered that the Sun’s powerful magnetic field is having a big influence on UK lightning rates,” said Dr Matt Owens of the Department of Meteorology’s University of Reading, who is the lead author of the paper published in the journal Environmental Research Letters.
“The solar magnetic field is like a bar magnet, so as the Sun rotates its magnetic field alternately points toward and away from the Earth, pulling the terrestrial magnetic field one way and then another.”
It is hoped the finding could lead to a reliable lightning forecast system that could provide warnings of hazardous events many weeks in advance. To do so, weather forecasters would need to combine conventional forecasts with accurate predictions of the Sun’s spiral-shaped magnetic field known as the heliospheric magnetic field.
In this study, Dr Owen’s team used satellite and ground data to show that during 2001-2006, the UK experienced a 50 percent increase in thunderstorms when the heliospheric magnetic field pointed towards the Sun and away from Earth.
This change of direction can temporarily bend the Earth’s magnetic field and allow a shower of cosmic energetic particles from across the Universe to enter the upper atmosphere.
“From our results, we propose that galactic cosmic rays are channeled to different locations around the globe, which can trigger lightning in already charged-up thunderclouds,” Dr Owens said.
“The changes to the Earth’s magnetic field could also make thunderstorms more likely by acting like an extra battery in the atmospheric electric circuit, helping to further charge up clouds.”
“This latest finding is an important step forward in our knowledge of how the weather on Earth is influenced by what goes on in space,” said co-author Prof Giles Harrison of the University of Reading.
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M.J. Owens et al. 2014. Modulation of UK lightning by heliospheric magnetic field polarity. Environ. Res. Lett. 9, 115009; doi: 10.1088/1748-9326/9/11/115009