Measurements of the amplitude-probability distributions of atmospheric noise in a power bandwidth of 370c/s, made at the Radio Research Station, Slough, England, during the International Geophysical Year, are presented for frequencies of 24kc/s, 135kc/s, 11Mc/s and 20Mc/s. The diurnal and seasonal variations of the noise power and average value of the noise envelope are derived, and a comparison is made between the measured noise power and predictions prepared under the auspices of the International Radio Consultative Committee (C.C.I.R.).The distributions are normalized to the r.m.s. level and summarized in representative curves. The variations of these composite distributions are expressed in statistical terms, with particlar reference to the r.m.s. to average ratio and the overall dynamic range.