COSMIC RAYS AND CLOUDS
On the 17th of August this year, a few of us from Vagaries had the privilege of visiting the Cloud Physics Laboratory in Mahabaleshwar, on the invitation of IITM, under guidance from Rajesh sir. It was interesting to see the various instruments used to study the formation of clouds and their various attributes using physical and chemical methods.
One of the instruments we saw was a cloud chamber. This is used to analyse the formation of water droplets when a charged particle passes by. One of the reasons for formation of water droplets that eventually collectively form a cloud which produces rain, is cosmic rays.
Cosmic rays are atomic fragments that rain down on Earth from outside the solar system. Their origins are mysterious and some scientists claim supernovas as the point of origin. Recently the Pierre Auger Observatory ( Argentina) studied the trajectory of 30,000 particles. "It concluded that there is a difference in how frequently these cosmic rays arrive, depending on where you look. While their origins are still nebulous, knowing where to look is the first step in learning where they came from, the researchers said. (space.com)"
The Solar activity/cosmic ray link climate modulation system can be summarized by the following chart:
So essentially cosmic rays help in the formation of 1-2nm sized Ions. These coalesce to form 20nm sized and then 50nm sized Cloud Condensation Nuclei (CCN). These lead to further 15micrometer sized cloud droplets.
But what is the actual link between cosmic rays and clouds? Mr. Henrik Svensmark, Danish scientist, recently made a presentation at the 12th International Climate Conference in Munich, where he showed the link between solar activity via cosmic rays and cloud cover and how this cloud cover influences climate.