06 August, 2009, 12:01
Clouds may seem one of the most familiar things in our lives, but scientists still fail to fully explain how they come into existence. A new study says cosmic rays contribute to cloud formation.
Cosmic rays are high-energy particle beams travelling through space at high speeds. According to a theory proposed by physicist Henrik Svensmark of the Technical University of Denmark in Copenhagen, the rays collide with water molecules in the atmosphere, turning them into charged ions. Those can then attract other water molecules, eventually forming nuclei for droplets, much like dust and pollen can do.
The team led by Svensmark proved the process possible in a lab in 2006. In a new study they proved it can happen in nature also, reports Science.
Researchers focused on a phenomenon called Forbush decrease, when cosmic rays are blocked from Earth by a massive ejection of plasma coming from the Sun. They have analyzed statistical data on clouds gathered by weather satellites over the past 22 years and compared them with 26 registered Forbush decreases. For the five strongest events they report an average 7% decrease of droplet content in the Earth’s clouds. Eventually, in a matter of weeks, the cloud patterns reverted to normal.
“We are now convinced that aerosols are affected by the Forbush decrease,” Svensmark said.
Clouds may seem one of the most familiar things in our lives, but scientists still fail to fully explain how they come into existence. A new study says cosmic rays contribute to cloud formation.
Cosmic rays are high-energy particle beams travelling through space at high speeds. According to a theory proposed by physicist Henrik Svensmark of the Technical University of Denmark in Copenhagen, the rays collide with water molecules in the atmosphere, turning them into charged ions. Those can then attract other water molecules, eventually forming nuclei for droplets, much like dust and pollen can do.
The team led by Svensmark proved the process possible in a lab in 2006. In a new study they proved it can happen in nature also, reports Science.
Researchers focused on a phenomenon called Forbush decrease, when cosmic rays are blocked from Earth by a massive ejection of plasma coming from the Sun. They have analyzed statistical data on clouds gathered by weather satellites over the past 22 years and compared them with 26 registered Forbush decreases. For the five strongest events they report an average 7% decrease of droplet content in the Earth’s clouds. Eventually, in a matter of weeks, the cloud patterns reverted to normal.
“We are now convinced that aerosols are affected by the Forbush decrease,” Svensmark said.
