As grotesque as the title may appear to suggest, I basically want to understand just that. Why is it that EM radiation of each group of wavelengths (visible, IR, UV etc.) manages to penetrate materials with varying ease. From what I've seen so far - and I haven't studied this directly, I'm just curious - there doesn't seem to be any consistency with the relationship between the wavelength of the radiation and the penetrating ability with each material. e.g. light passes through the atmosphere very well, while the shorter wavelength UV radiation has a much harder time getting through the atmosphere. So from this statistic, it might be concluded that shorter wavelength radiation cannot penetrate matter as well. However, gamma radiation manages to go through much thicker metals than any other longer wavelength types. So, is the penetrating ability of each group of radiation dependant upon the material and its properties (because the gases in the atmosphere shouldn't be strictly compared to a metal) or is it dependant upon the properties of each wavelength of radiation?