Possible mechanisms for sun-weather relationships

There is no doubt that the sun affects the weather, nor that solar variation leads to a corresponding variation in the weather. What is in doubt is that such an association has been correctly identified and broadly described by the available data. Normally, belief in the validity of data is conditioned by some reasonable h~theti~ connection between cause and effect. At present there are no strong theories for such a connection. There remains various statistical tests. These, again, lack a physical hypothesis to be tested. Some of these statistics suggest that extremely high confidence should be placed in the stated sun-weather relationship. I suspect that these tests express the improbability of some exceedingly unlikely physical hypotheses. HINES and HALFSY (1976) suggest confidence limits of 1 chance in 20 for a certain relation. This seems about right to me, and an adequate basis for studying the association. Passage of solar magnetic-sector boundaries detected at the Earth have a time scale of about 1 week. Association with the generation of vorticity and enhancement of troughs suggested by WILCOX et al. (1974). Solar rotation period of (nearly) 27.5 days detected in solar flux at 10.7 cm and sunspot number. Associated with ionospheric critical frequencies, height of the 500 mb surface, surface pressure by KING et al. (1977) and persistence of anticyclones, known as blocking, more recently. Sunspot cycle associated with surface pressure, thunderstorm activity, tree-ring width over 2000 years, various climatic trends. Many other associations have been suggested and it is not obvious that the ones listed here have the same cause, but it is a reasonable supposition.