Image of the Day: Giant Natural Particle Accelerators 40 Kilometers Above Earth

1004132028508321925 A lightning researcher at the University of Bath has discovered that during thunderstorms, giant natural particle accelerators can form 40 kilometers above the surface of the Earth — a fascinating example of the interaction between the Earth and the Universe. In the next few years five different planned space missions (the TARANIS, ASIM, CHIBIS, IBUKI and FIREFLY satellites) will be able to measure the particle beams directly.

When intense lightning discharged in thunderstorms coincides with high-energy particles coming in from space (cosmic rays), nature provides the right conditions to form a giant particle accelerator above the thunderclouds.

The cosmic rays strip off electrons from air molecules that are accelerated upwards by the electric field of the lightning discharge. The free electrons and the lightning electric field then make up a rare natural particle accelerator.

The accelerated electrons then develop into a narrow particle beam which can propagate from the lowest level of the troposphere, through the middle atmosphere and into near-Earth space, where the energetic electrons are trapped in the Earth's radiation belt. For the blink of an eye, the power of the accelerator's electron beam can be as large as the power of a nuclear power plant.

These radio waves were predicted by Dr. Robert Roussel-Dupré using computer simulations at the Los Alamos National Laboratory supercomputer facility.

A team of European scientists, from Denmark, France, Spain and the UK  monitored the area above thunderstorms in southern France with video cameras and reported lightning discharges which were strong enough to produce transient airglows above thunderstorms known as sprites. A small fraction of which were found to coincide with the particle beams.

The zone above thunderstorms has been a suspected natural particle accelerator since the Scottish physicist and Nobel Prize winner Charles Thomson Rees Wilson speculated about lightning discharges above these storms in 1925.

The Daily Galaxy via

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Image top of page: The image shows a transient airglow or 'sprite' above a thunderstorm in France in September 2009. (Credit: Serge Soula / Oscar van der Velde)


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