"The impact of cosmic rays on the climate could be greater than scientists suspect after experiments showed they may have a pivotal role in cloud formation.
Researchers have managed to replicate the effect of cosmic rays on the aerosols in the atmosphere that help to create clouds. Henrik Svensmark, a weather scientist in Denmark, said the experiments suggested that man’s influence on global warming might be rather less than was supposed by the bulk of scientific opinion.
Cosmic rays ― radiation, or particles of energy, from stars, which bombard the Earth ― can create electrically charged ions in the atmosphere that act as a magnet for water vapour, causing clouds to form. [...]"