Atmospheric electrical conductivity variations over different environments

Atmospheric electrical conductivities have been monitored at a coastal site having a large deposit of radioactive minerals. Conductivities were also monitored at two other sites, one coastal and the other inland, both non-radioactive. The ratio of conductivity at the radioactive site to that at the others is about 6, in agreement with the ratio of radioactivity. The diurnal variation pattern at this site in May, a pre-monsoon month, agrees with the known variation of radon concentration in air. However, in June, a monsoon month, it is different, a double oscillation similar to that at the other sites. With the onset of the monsoon, conductivity at the radioactive site shows a large decrease, which is not seen at the other sites. The ratio of positive polar conductivity to negative polar conductivity shows a reduction after the onset of the monsoon rainfall. The diurnal variation pattern shows differences between pre-monsoon and monsoon periods at the radioactive site, while there is no change at the non-radioactive sites. The diurnal variation at all these sites in all seasons shows a sharp decrease starting at about 0400 hrs local time and reaching a minimum at about 0800 hrs. Such a decrease has been attributed to human activity associated with sunrise. The present results, however, suggest that this may be incorrect. Fourier analysis of the data shows that there exists a strong semi-diurnal component that is inversely correlated with the clearly seen semi-diurnal variation in pressure in the tropics.