Editing Electromagnetic radiation (section)

== Atmosphere and magnetosphere ==
{{Main|ozone layer|shortwave radio|skywave|ionosphere|atmospheric window|optical window}}
[[File:Atmospheric electromagnetic opacity.svg|thumb|upright=2.25|Rough plot of Earth's atmospheric absorption and scattering (or [[opacity (optics)|opacity]]) of various [[wavelength]]s of electromagnetic radiation]]
Most UV and X-rays are blocked by absorption first from molecular [[nitrogen]], and then (for wavelengths in the upper UV) from the electronic excitation of [[dioxygen]] and finally [[ozone]] at the mid-range of UV. Only 30% of the Sun's ultraviolet light reaches the ground, and almost all of this is well transmitted.

Visible light is well transmitted in air, a property known as an [[optical window|atmospheric window]], as it is not energetic enough to excite nitrogen, oxygen, or ozone, but too energetic to excite molecular vibrational frequencies of water vapor and carbon dioxide.<ref>{{cite book |last1=Tao |first1=Jiasheng |title=Space Optical Remote Sensing |publisher=Springer, Singapore |isbn=978-981-99-3318-1 |chapter=Radiation Source and Optical Atmospheric Transmission |series=Advances in Optics and Optoelectronics |date=2023 |pages=111–188 |doi=10.1007/978-981-99-3318-1_4}}</ref> Absorption bands in the infrared are due to modes of vibrational excitation in water vapor. However, at energies too low to excite water vapor, the atmosphere becomes transparent again, allowing free transmission of most microwave and radio waves.<ref>{{cite journal |last1=Chaplin |first1=Martin |title=Infared Spectroscopy |date=May 15, 2013 |page=water.lsbu.ac.uk |url=https://www.ifsc.usp.br/~lavfis2/BancoApostilasImagens/ApLuminescencia/Infrared%20Spectroscop1.pdf |access-date=April 19, 2022 |archive-date=24 March 2022 |archive-url=https://web.archive.org/web/20220324185050/https://www.ifsc.usp.br/~lavfis2/BancoApostilasImagens/ApLuminescencia/Infrared%20Spectroscop1.pdf |url-status=dead }}</ref>

Finally, at radio wavelengths longer than 10&nbsp;m or so (about 30&nbsp;MHz), the air in the lower atmosphere remains transparent to radio, but plasma in certain layers of the [[ionosphere]] begins to interact with radio waves (see [[skywave]]). This property allows some longer wavelengths (100&nbsp;m or 3&nbsp;MHz) to be reflected and results in [[shortwave radio]] beyond line-of-sight. However, certain [[Ionosphere#D layer|ionospheric effects]] begin to block incoming radiowaves from space, when their frequency is less than about 10&nbsp;MHz (wavelength longer than about 30&nbsp;m).<ref>{{Cite journal|last=Dabas|first=R S|title=Ionosphere and its influence on radio communications|journal=Resonance|language=en|volume=5|issue=7|pages=28–43|doi=10.1007/bf02867245|issn=0971-8044|date=July 2000|s2cid=121347063}}</ref>