We use experimental data to show that the amplitudeA of the oscillations impressed upon upper atmospheric electrons by the electric field vectors of incident solar radiation increases with the solar energy wavelength λ over the visible spectrum. Calculations based upon experimental data show that the transmission coefficientT of the upper atmosphere for incident solar energy (say at intensityI 0) also increases with λ over the visible spectrum, implying thatT increases withA over the latter range. Finally we show thatI 0 1/2 λ2 bears a positive linear relationship withT over the visible solar spectrum. The latter conclusion, which confirms theoretical results contained in a recent paper, is then used to show that the 100 000 year eccentricity cycle effectively causes a maximum change in the total solar energy reaching the lower atmosphere of approximately 4.5% which is enough to trigger an ice age.