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Proc. R. Soc. A doi:10.1098/rspa.2011.0040
 

Summary: Proc. R. Soc. A
doi:10.1098/rspa.2011.0040
Published online
Cloud base height and cosmic rays
BY R. GILES HARRISON*, MAARTEN H. P. AMBAUM
AND MICHAEL LOCKWOOD
Department of Meteorology, University of Reading, PO Box 243, Earley Gate,
Reading RG6 6BB, UK
Cosmic rays modify current flow in the global atmospheric electrical circuit. Charging
at horizontal layer cloud edges has been observed to be consistent with global circuit
vertical current flow through the cloud, which can modify the properties of small and pure
water droplets. Studies have been hampered by the absence of cloud edge observations,
hence cloud base height information is investigated here. Cloud base height measured at
the Lerwick Observatory, Shetland, UK, is analysed using threshold tests and spectral
analysis. The cloud base height distributions for low cloud (cloud base less than 800 m)
are found to vary with cosmic ray conditions. Further, 27 day and 1.68 year periodicities
characteristic of cosmic ray variations are present, weakly, in the cloud base height data
of stratiform clouds, when such periodicities are present in neutron monitor cosmic ray
data. These features support the idea of propagation of heliospheric variability into layer
clouds, through the global atmospheric electric circuit.

  

Source: Ambaum, Maarten - Department of Meteorology, University of Reading

 

Collections: Geosciences