Radio atmospheric the Earth's surface and the ionospheric D- and E- layers. Whistlers generated by lightning strokes can propagate into the magnetosphere along the geomagnetic lines of force. Finally, upper-atmospheric lightning or sprites, that occur at mesospheric altitudes, are short-lived electric breakdown phenomena, probably generated by giant lightning events on the ground. In a typical cloud-to-ground stroke (R stroke), negative electric charge (electrons) of the order of Q = 1 C stored within the lightning channel is lowered to the ground within a typical impulse time interval of τ = 100 μs. This corresponds to an average current flowing within the channel
Radio propagation propagation. The interference between the direct beam line-of-sight and the ground reflected beam often leads to an effective inverse-fourth-power (1/distance) law for ground-plane limited radiation. Lower frequency (between 30 and 3,000 kHz) vertically polarized radio waves can travel as surface waves following the contour of the Earth; this is called "groundwave" propagation. In this mode the radio wave propagates by interacting with the conductive surface of the Earth. The wave "clings" to the surface and thus follows the curvature of the Earth, so groundwaves can travel over mountains and beyond the horizon. Ground waves propagate in vertical polarization so vertical