A series of observations of the atmospheric potential gradient have been made over a period of six years and have been correlated with positions of the sun-spots and weather conditions. Maxima or minima of the potential gradient and storms appear to recur at intervals of approximately 27 days and at the same time that sun-spots appear near a plane through the axis of the sun and the earth. The supposition is made that the variations of the potential gradient and the storms are associated with radiation which travels approximately with the velocity of light from the sun. Since the light received from the sun-spot group cannot change rapidly as the group passes its position of nearest approach to the earth it seems more reasonable to suppose that a radiation not distributed according to Lambert's cosine law is involved.