The upper atmosphere as a parallel combination of three variable bandpass filters

Summary We show that the upper atmosphere acts as a parallel combination of three main variable bandpass filters whose bandwidths extend from ∼10¹³ to ∼10¹⁵ Hz, ∼3 MHz to ∼10 GHz and ∼40 Hz to ∼10 kHz. The transmission coefficient of the first bandwidth increases as the intensity of the incident electromagnetic radiation within its passband increases. One consequence of the latter is that the eccentricity effects of the Earth's orbital geometry are (stochastically) amplified. This apparently explains why the 100 000 year eccentricity cycle cannot be predicted by the Milankovitch version of the astronomical theory or any other version that involves a linear response. Revised version of a paper presented at an International Symposium on ?Environmental Protection? held at Dar es Salaam, Tanzania from 6 to 15 May 1988.