Diurnal Cycle

Any pattern that recurs every 24 hours as a result of one full rotation of the Earth. As the Earth rotates on its axis, creating the cycle of night and day, there is a delay between the time when the earth-atmosphere system is irradiated and when the temperature begins to increase on the surface of the planet.  Diurnal cycles have a direct correlation with radon levels therefore it is recommended, whenever possible and practical to conduct measurement durations in full diurnal (24-hour) cycles.