New research, published in Environmental Research Letters, suggests that the number of lightning events across the UK has been strongly influenced by solar activity – specifically the Sun’s magnetic field.
It may come as a surprise that we are still somewhat puzzled by lightning. It is not fully understood how the built up electric charges actually reach the ground, for example. This is because the air we breathe is not a good conductor of electricity. The theory that best fits at the moment is that these cosmic rays allow for the current to form a lightning bolt.
The research has suggested that the orientation of the Sun’s magnetic field bends the Earth’s magnetic field. As the star spins, sometimes the field is pointing towards the earth, sometimes away.
Dr Matt Owens from the University of Reading said: “What we think is happening is that the Sun’s magnetic field is pulling or pushing on the Earth’s field and that’s letting energetic charged particles down into the atmosphere at different locations and the idea is that these actually trigger lightning”.
He added: “For lightning, you need a thin conducting channel like a wire, and galactic cosmic rays can provide this thin column of ionisation in the atmosphere”.
Over five years, the UK showed a 50% increase in thunder and lightning rates, which corresponds to Sun’s field pointing away from the Earth.