What are the differences between UV-A, UV-B and UV-C radiation?
UV-A radiation refers to atmospheric radiation from 320 nm-400 nm (that’s 0.320-0.400 m m). UV-A is very important to photosynthesis and plant studies. UV-B is the shortest wavelength atmospheric radiation that actually reaches the ground, and covers from 280-320 nm (that’s 0.280-0.320 nm). However, it is UV-B that causes skin cancer over prolonged exposure. Due to the strong absorption of UV-B by ozone, the actual amount of UV-B reaching the ground is highly seasonal and depends on the solar zenith angle. With a high enough resolution instrument, the UV-B spectrum will be seen to be highly variable, i.e., it is characterized by spikes and troughs instead of being a smooth curve. This spectral structure of the sun’s radiation arises from atomic absorption within the sun’s approximately 6000 K photosphere. Instruments exist both to measure the total integrated broadband radiation (e.g. the YES UVB-1), as well as to measure radiation along narrow wavelengths (e.g. high resolution narrowb
