Editing Solar cycle (section)

==== Organisms ====
The impact of the solar cycle on living organisms has been investigated (see [[chronobiology]]). Some researchers claim to have found connections with human health.<ref>{{cite journal | journal = Neuroendocrinology Letters | title = Cross-spectrally coherent ~10.5- and 21-year biological and physical cycles, magnetic storms and myocardial infarctions | date = 2000 | pages = 233–258 | url = http://www.nel.edu/21_3/3StoryBeh_Halb.htm | volume = 21 | issue = 3 | pmid = 11455355 | last2 = Cornélissen | first2 = G | last3 = Otsuka | first3 = K | last4 = Watanabe | first4 = Y | last5 = Katinas | first5 = GS | last6 = Burioka | first6 = N | last7 = Delyukov | first7 = A | last8 = Gorgo | first8 = Y | last9 = Zhao | first9 = Z | last1 = Halberg | first1 = F | archive-url = https://web.archive.org/web/20080729003640/http://www.nel.edu/21_3/3StoryBeh_Halb.htm | archive-date = 2008-07-29 }}</ref>

The amount of ultraviolet UVB light at 300&nbsp;nm reaching the Earth's surface varies by a few percent over the solar cycle due to variations in the protective [[ozone layer]]. In the stratosphere, [[ozone]] is [[Ozone-oxygen cycle|continuously regenerated]] by the [[Photodissociation|splitting]] of [[Oxygen|O<sub>2</sub>]] molecules by ultraviolet light. During a solar minimum, the decrease in ultraviolet light received from the Sun leads to a decrease in the concentration of ozone, allowing increased UVB to reach the Earth's surface.<ref>{{cite book |chapter-url=https://www.nap.edu/read/4778/chapter/5#66 |title=Solar Influences on Global Change |chapter=Solar Variations, Ozone, and the Middle Atmosphere |author=National Research Council |year=1994 |pages=66–68 |location=Washington DC |publisher=National Academies Press |doi=10.17226/4778|hdl=2060/19950005971 |isbn=978-0-309-05148-4 }}</ref><ref>{{cite journal |first1=E |last1=Echer |first2=VWJH |last2=Kirchhoff |first3=Y |last3=Sahai |first4=N |last4=Paes Leme |title=A study of the solar cycle signal on total ozone over low-latitude Brazilian observation stations |journal=Advances in Space Research |volume=27 |issue=12 |year=2001 |pages=1983–1986 |doi=10.1016/S0273-1177(01)00270-8|bibcode=2001AdSpR..27.1983E }}</ref>