In the present paper the AA. search an eventual phenomenon<br />with the universal diurnal variation, which may influence the<br />natural terrestrial phenomena. Considering that the first cause of the<br />diurnal variations is the solar radiation arriving 011 the Earth, such a phenomenon<br />may be founded in the diurnal rotation of the Earth, therefore<br />1 lie regions illuminated by the sun are different according to the universal<br />time. Since the regions of the Earth have different albedo, the solar radiation<br />absorbed by the entire Earth will have an universal diurnal variation.<br />The A A. have calculated the apparent surface (with the sun as a point<br />of view) of the lands and of the seas at different hours (U.T.) and in the<br />different period of the year.<br />In order of include in computation the absorption of the solar radiation<br />by the atmosphere, the AA. have calculated these surfaces with a<br />correction due to this absorption. In these computations the eventual<br />cloudiness not appears, because in this first approximation the cloudiness<br />is supposed equal 011 the entire Earth. These surfaces with the correction<br />of the atmospheric absorption are proportional to the solar energy really<br />absorbed by the entire Earth.<br />By the comparison of the universal diurnal variation of those surfaces<br />with that of a natural phenomenon (the atmospheric electric field), the<br />AA. show that it is possible, with some reductions, to make these variations<br />coincide. These reductions are an advance of the maximum (4 hours) and<br />a coefficient which reckons the albedo's difference.<br />The AA. recognize that it is no possible with this preliminary study<br />to explain the influence of the solar energy absorbed by the entire Earth<br />011 the atmospheric electric field; but according to the AA. this correlation<br />will take an important contribution also to the researches for the general<br />atmospheric circulation.