Thought this was interesting, I'd like to see the results
In Honour of Warfish:
Oct 26th 2006
From The Economist print edition
A new experiment to test the role of cosmic rays in global warming
SIR WILLIAM HERSCHEL, an 18th-century astronomer, is credited with being the first person to notice the effect of variations in the sun's activity on the Earth. In 1801 he observed that when the sun had many spots on its surface, the price of wheat fell—a connection he attributed to the weather being more temperate. Over the next 200 years scientists tried, without much success, to understand exactly how these transient sunspots might affect the climate. Now an experiment has begun that could explain what is going on.
The Earth is continually bombarded by streams of particles that come from outside the solar system. These cosmic rays, as they are called, consist mostly of protons. They strike the gases of the Earth's atmosphere at great speeds, creating showers of debris including streams of electron-like particles called muons. An international team of physicists led by Jasper Kirkby, who works at CERN, the European particle physics laboratory near Geneva, has devised an experiment to find out how this process might affect the climate.
When scientists first turned their attention to subatomic particles, including cosmic rays, they used a device called a cloud chamber to study them. These are boxes containing air that is super-saturated with water vapour. When a charged particle zips through the chamber, the vapour condenses into a trail of droplets showing the particle's path and, if the box is placed in a magnetic field, its electrical charge.
In an updated version of a cloud chamber the researchers are recreating the Earth's atmosphere. They fill the container with pure air made by evaporating liquid nitrogen and liquid oxygen, and add water vapour and some trace gases. They adjust the temperature and pressure of the mix to mimic conditions at various heights above sea level. Then they zap the results with a stream of particles from the laboratory's elderly proton synchrotron. Ideally, they would use muons but, in practice, they are using a close cousin, the pion.
The theory is that when a muon encounters a gas molecule, it can knock off an electron, leaving a positively charged ion in its wake. The electron soon attaches itself to another molecule, making a negatively charged ion. These ions are thought to help create new particles called aerosols and, when aerosols grow above a certain size, they become the seeds around which cloud droplets form.
The experiment is testing this theory. If it is correct, then cosmic rays may create clouds with more small droplets than would otherwise be the case. Such clouds would persist for an unusually long time because small water droplets are less likely than big ones to turn into rain. Physicists also think that such clouds would be brighter and more reflective than normal clouds. So they would cool the Earth by hanging around and by reflecting more heat from the sun back into space.
The link between the sun's activity and climate involves another lot of particles streaming past the Earth. The planet and its neighbours are bathed in the solar wind, a stream of charged particles ejected from the upper atmosphere of the sun. The magnetic field associated with these particles helps protect the Earth from cosmic rays by deflecting them from the planet.
When the sun is at its most active, which is when it is spotty, the solar wind is stronger and fewer cosmic rays penetrate. Conversely, when solar activity is less intense, more cosmic rays get through. A study using data on cloud cover taken from satellite images dating from 1979 found that 65% of the world's skies were covered by cloud when cosmic rays were weakest and 68% when they were strongest.
Scientists modelling climate change have ignored cosmic rays up to now because there was not enough evidence about how they might work. However, the results of this experiment, expected by summer 2007, could show how nature periodically sticks her oar in. The experiment on cloud formation also seems likely to undermine the particle physics laboratory's reputation for pursuing only blue skies research.