How does radiation appear in the atmosphere?

-- A gradient (change) in temperature, pressure, and humidity with altitude can bend the path of radio waves. The effect is independent of frequency. -- Ionized atmosphere, such as intermittently arises between roughly 70 to 250 miles above the surface, reflects radio waves at the lower frequencies ... below perhaps 35 MHz depending on the depth and intensity of the ionized layers. -- The presence of rain, sleet, and fog can attenuate the radio waves by absorbing some of the RF energy. The effect is greater at higher frequencies (essentially negligible below perhaps 8 GHz). -- Atmospheric gases alone exhibit non-negligible absorption of RF at high microwave frequencies, e.g. 28 GHz and above. -- High winds can have a significant effect on the transmission of E&M waves, not so much in any way that would have interested Maxwell, but rather when an antenna is blown off path due to loose or under-rated mounting hardware. Ask me about it !