Clouds in a jar
A new experiment with old apparatus reveals a flaw in models of the climate
The Economist
CLOUD chambers have an honoured place in the history of physics. These devices, which generate vapour trails that mark the passage of high-energy subatomic particles, were the first apparatus that allowed such passage to be tracked. That was in the 1920s and led, among other things, to the discovery of cosmic rays. Science has moved on since then, of course, and cloud chambers are now largely museum pieces. But the world’s leading high-energy physics laboratory, CERN, outside Geneva, is dusting the idea off and putting it into reverse. Instead of using clouds to study cosmic rays, it is using cosmic rays to study clouds. In doing so, it may have thrown a spanner into the works of the world’s computer models of the climate.