Wednesday, January 12, 2011
Thunderstorms, antimatter, and asthma
Image produced by J. Dwyer/FIT, NASA, from this site.
What is antimatter? It is matter composed of antiparticles. Consider our normal particles, electrons and protons, that are the building blocks of normal matter. For example, one electron and one proton combine to become hydrogen. The anti-electron (called a positron) has the same mass as an electron, but the opposite electric charge--in this case, a positive charge. The antiproton would have the mass of a proton, but a negative charge. An antihydrogen atom then consists of an antiproton and an antielectron. Mixing of matter and antimatter results in the annihilation of both, with the production of high energy photons, that is, gamma rays and other particle-antiparticle pairs. Modern concepts of antimatter began in the 1920's when Paul Dirac realised that the Schrodinger wave equation predicted the possibility of antielectrons, which were then discovered by Carl Anderson in 1932. The study of antimatter has largely been the realm of astrophysicists and physicists, but they have been used in medical imaging in positron emission tomograpy (PET).
Scientists using the Fermi Gamma-ray Space Telescope have announced that they have detected beams of antimatter produced by thunderstorms on earth. This was announced by Michael Briggs, a of the Gamma-ray Burst Monitor (GBM) on January 11 at a meeting of the American Astronomical Society. NASA's Fermi spacecraft is designed to monitor gamma rays. The GBM monitors both outer space and the Earth below its orbit. When antimatter strikes Fermi and collides with a particle of normal matter, both particles are annhilated and the GBM detects the high energy gamma rayss produced. In most cases the gamma rays were detected above thunderstorms directly below the GBM, but a few were detected quite far away, as far as 2800 km in one case. Even though the storms were below Fermi's horizon, gamma rays that were produced by it travelled up the earth's magnetic field and struck the spacecraft. Further information is here.
When Googling for information about this phenomenon, I came across a 2008 study by a team of meteorologists and epidemiologists who had found that emergency room visits by asthematics increased in the days after a thunderstorm. They believe that the associated rain and wind break up pollens and spread them around over distances greater than the thunderstorm itself. I remember being surprised when I moved to Illinois that it was such a hotbed of allergies and asthma. What was there to be allergic to here but corn and soybeans? Well, there are other plants than corn and soybeans, and there are lots of thunderstorms!
Other blogs on this site related to storms and weather can be found here: super typhoon Megi,, winter storms in Europe and the Arctic Oscillation, football can be dangerous, and volcanoes and atom bombs.