A mathematical description of the diurnal variation of radon progeny.

The variation of the alpha radioactivity in the air near the ground and the ground-level total gamma radiation has been monitored in North-eastern Greece over several days. Meteorological information regarding the temperature of the air and humidity has been simultaneously recorded. The alpha-radioactivity shows a periodic diurnal variation with a peak in the morning followed by a decrease in the afternoon; then, the variation rises again to the peak the next morning. The variation of the ground gamma-radiation follows that of the air alpha-radioactivity. Furthermore, their significant dependence on the air temperature and humidity is confirmed, rising with an increase in humidity and a decrease in temperature. Hence, a mathematical function has been developed to describe the diurnal variation of the alpha-radioactivity in terms of the ground-level gamma-radiation and the meteorological variables of temperature and humidity.