A new study suggests that lightning is triggered by cosmic rays. Cosmic rays are highly charged particles believed to have originated outside of the solar system and have penetrated Earth's atmosphere.
The study is the first to use Low Frequency Array (LOFAR), a network of radio antennas and particle detectors spread around five European countries developed to study radio waves produced by cosmic rays in the Earth's atmosphere. Earlier studies used airborne equipment, such as sounding rockets and balloons.
Astrophysicist Heino Falcke from Radboud University Nijmegen in the Netherlands used the radio observatory to monitor the electromagnetic bursts caused by cosmic rays and to measure the electricity inside the thunderclouds.
"Thunderstorm electric fields have been tricky to measure, and there is a lot of uncertainty about how big the fields can get," Joseph Dwyer, an atmospheric physicist at the University of New Hampshire in Durham, told APS News. "Having a technique like this to remotely measure the electric field is very useful and may help us make progress in understanding thunderstorms and lightning."
The researchers observed that when a cosmic ray particle hits an air molecule, a chain reaction is formed, which sends millions of electrons to the ground. The charged particles are detected by the radio observatory. They then feed the information to the computer models to simulate the movements of the cosmic ray particles in the atmosphere. They observed that the particles are all in one line during a fair weather then scattered when a thundercloud is in the air.
The researchers decided to redesign their computer models to add the electric fields in the thunderclouds to see if there will be changes on the arrangement of the cosmic ray particles. The new simulations showed that the particles remained scattered whether a thundercloud is nearby or not which is exactly what they predicted.
"This paper is groundbreaking since it demonstrates that the idea actually works," Dwyer said to Nature.com
The study was published in April 24 issue of Physical Review Letters.
