Cosmic raise in cloud (Forwarded)

University of Reading
Reading, U.K.

Media contact:

Dr Giles Harrison
Department of Meteorology, The University of Reading
Tel: +44 (0)118 378 6690

Dr David Stephenson
Department of Meteorology
Tel: +44 (0)118 378 6296

Craig Hillsley, Press Officer
The University of Reading
Tel: +44 (0)118 378 7388

Release date: January 18, 2006

Cosmic raise in cloud

New evidence that events in outer space affect the weather and climate of
Earth has been revealed in a study by meteorologists at the University of
Reading published in the Proceedings of the Royal Society on Wednesday 18
January.

In their paper 'Empirical evidence for a non-linear effect of galactic
cosmic rays on clouds', Drs Giles Harrison and David Stephenson suggest
that cosmic rays have a significant effect on the Earth's lower atmosphere
-- particularly on levels of cloudiness.

The Reading meteorologists discovered that the chance of an overcast day
decreases by 20% on days with low cosmic ray fluxes. The effect is
strongest when low cosmic ray fluxes occur -- this is often associated
with solar flares, but may also result from changes outside the solar
system.

"Back in 1959, Edward Ney suggested that variations in cosmic rays, which
are charged particles mostly originating outside the solar system, could
affect our weather," said Dr Harrison. "This research now provides strong
evidence supporting Ney's suggestion, which effectively links atmospheric
and space science."

"As well as the influence of weather, our evidence shows a small yet
statistically significant effect of cosmic rays on daily cloudiness. This
suggests that cosmic rays are an additional external source of climate
variability that should be considered when modelling past and future
climate."

To detect changes in the atmosphere from cosmic rays, Harrison and
Stephenson used solar radiation measurements made by meteorological
stations. They conducted a careful analysis of the UK archives of daily
solar radiation observations from 1951-2004 and compared them with neutron
counter cosmic ray measurements taken at Climax, Colorado, between 1951
and 2000.

End

Notes for editors

1. In 1927, the British physicist C.T.R. Wilson received the Nobel Prize
for the cloud chamber, which he invented to simulate atmospheric cloud
processes. The cloud chamber makes cosmic rays visible by condensing water
droplets on ions produced by the cosmic rays. Wilson developed the cloud
chamber in the 1890s to simulate atmospheric cloud production processes.
He initially thought that ions provided all the nuclei in the atmosphere
for cloud formation, but subsequently discovered that clouds formed on
uncharged particles too. The mechanism suggested by Harrison and
Stephenson to explain the effect of cosmic rays on clouds found is
different to Wilson's, and depends on the particles formed by ions, rather
than the action of the ions themselves. This is an important distinction,
as the cloud chamber does not reproduce real atmospheric conditions.
Wilson's work was also published in the Proceedings of the Royal Society.

2. Cosmic rays were discovered by Viktor Hess, following a high altitude
balloon flight in August 1912. Hess received the Nobel prize for the
discovery in 1936. (http://www.ast.leeds.ac.uk/haverah/cosrays.shtml)

3. The archive meteorological measurements used for this study were
originally obtained by the UK Met Office. These solar radiation
measurements began at Kew Observatory in 1947, and have continued at nine
other sites across the UK, from Jersey to Lerwick. Measurements of solar
radiation continue at the University of Reading.

The Cosmic ray measurements used in this study were obtained from the
Climax neutron monitor station
(http://ulysses.sr.unh.edu/NeutronMon...ackground.html)