Cosmic rays and cloud formation
Scientists has reproduced the Earth’s atmosphere in the laboratory and proved that clouds are seeded in part by incoming cosmic rays. Fluctuations in the cosmic-ray flux caused by changes in solar activity could play a role in climate change.
Cosmic rays are very high-energy particles, mainly originating outside the Solar System. They may produce showers of secondary particles that penetrate and impact the Earth’s atmosphere and sometimes even reach the surface. Composed primarily of high-energy protons and atomic nuclei, they are of mysterious origin. Data from the Fermi space telescope (2013) have been interpreted as evidence that a significant fraction of primary cosmic rays originate from the supernovae of massive stars. However, this is not thought to be their only source. Active galactic nuclei probably also produce cosmic rays.
The term ray is a historical accident, as cosmic rays were at first, and wrongly, thought to be mostly electromagnetic radiation. In modern common usage high-energy particles with intrinsic mass are known as “cosmic” rays, and photons, which are quanta of electromagnetic radiation (and so have no intrinsic mass) are known by their common names, such as “gamma rays” or “X-rays”, depending on their frequencies.
Cosmic rays attract great interest practically, due to the damage they inflict on microelectronics and life outside the protection of an atmosphere and magnetic field, and scientifically, because the energies of the most energetic ultra-high-energy cosmic rays (UHECRs) have been observed to approach 3 × 1020 eV, about 40 million times the energy of particles accelerated by the Large Hadron Collider. At 50 J, the highest-energy ultra-high-energy cosmic rays have energies comparable to the kinetic energy of a 90-kilometre-per-hour (56 mph) baseball.
Cloud seeding, a form of intentional weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei, which alter the microphysical processes within the cloud. The usual intent is to increase precipitation (rain or snow), but hail and fog suppression are also widely practiced in airports.
Cosmoclimatology theory of climate change
Henrik Svensmark (born 1958) is a physicist and professor in the Division of Solar System Physics at the Danish National Space Institute (DTU Space) in Copenhagen. He is known for his theory on the effects of cosmic rays on cloud formation as an indirect cause of global warming.
Svensmark detailed his theory of cosmoclimatology in a paper published in 2007. The Center for Sun-Climate Research at the Danish National Space Institute “investigates the connection between solar activity and climatic changes on Earth”. Its homepage lists several publications earlier works related to cosmoclimatology.
Svensmark and Nigel Calder published a book The Chilling Stars: A New Theory of Climate Change (2007) describing the Cosmoclimatology theory that cosmic rays “have more effect on the climate than manmade CO2”:
“During the last 100 years cosmic rays became scarcer because unusually vigorous action by the Sun batted away many of them. Fewer cosmic rays meant fewer clouds—and a warmer world.”
A documentary film on Svensmark’s theory, The Cloud Mystery, was produced by Lars Oxfeldt Mortensen and premiered in January 2008 on Danish TV 2.