Editing Solar wind (section)

===Coronal mass ejection===
{{Main|Coronal mass ejection}}

[[File:Magnificent CME Erupts on the Sun - August 31.jpg|thumb|CME erupts from Earth's Sun]]
Both the fast and slow solar wind can be interrupted by large, fast-moving bursts of plasma called [[coronal mass ejection]]s, or CMEs. CMEs are caused by a release of magnetic energy at the Sun. CMEs are often called "solar storms" or "space storms" in the popular media. They are sometimes, but not always, associated with [[solar flare]]s, which are another manifestation of magnetic energy release at the Sun. CMEs cause shock waves in the thin plasma of the heliosphere, launching electromagnetic [[wave]]s and accelerating particles (mostly [[proton]]s and [[electrons]]) to form showers of [[ionizing radiation]] that precede the CME.<ref>{{Cite web|title=Coronal Mass Ejections {{!}} NOAA / NWS Space Weather Prediction Center|url=https://www.swpc.noaa.gov/phenomena/coronal-mass-ejections|access-date=2022-01-19|website=www.swpc.noaa.gov}}</ref>

When a CME impacts the Earth's magnetosphere, it temporarily deforms the Earth's [[magnetic field]], changing the direction of [[compass]] needles and inducing large electrical ground currents in Earth itself; this is called a [[geomagnetic storm]] and it is a global phenomenon. CME impacts can induce [[magnetic reconnection]] in Earth's [[Magnetosphere#Magnetic tails|magnetotail]] (the midnight side of the magnetosphere); this launches protons and electrons downward toward Earth's atmosphere, where they form the [[Aurora (phenomenon)|aurora]].

CMEs are not the only cause of [[space weather]]. Different patches on the Sun are known to give rise to slightly different speeds and densities of wind depending on local conditions. In isolation, each of these different wind streams would form a spiral with a slightly different angle, with fast-moving streams moving out more directly and slow-moving streams wrapping more around the Sun. Fast-moving streams tend to overtake slower streams that originate [[west]]ward of them on the Sun, forming turbulent co-rotating interaction regions that give rise to wave motions and accelerated particles, and that affect Earth's magnetosphere in the same way as, but more gently than, CMEs. 

CMEs have a complex internal structure, with a highly [[turbulent]] region of hot and compressed plasma (known as sheath) preceding an arrival of relatively cold and strongly magnetized plasma region (known as magnetic cloud or ejecta).<ref>{{cite journal |last1=Tsurutani|first1=B.T.|last2=Gonzalez|first2=W.D.|last3=Gonzalez|first3=A.L.C.|last4=Guarnieri|first4=F.L.|display-authors=et al.|title= Corotating solar wind streams and recurrent geomagnetic activity: A review | journal=Journal of Geophysical Research|date=2006-06-29|volume=111|issue=A7|doi=10.1029/2005JA011273|bibcode=2006JGRA..111.7S01T |url=http://urlib.net/sid.inpe.br/mtc-m16@80/2006/08.02.14.43 }}</ref> Sheath and ejecta have very different impact on the Earth's [[magnetosphere]] and on various [[space weather]] phenomena, such as the behavior of [[Van Allen radiation belts]].<ref>{{cite journal |last1=Pokhotelov|first1=D.|last2=Rae |first2=I.J.|last3=Murphy|first3=K.R.|last4=Mann|first4=I.R.|display-authors=et al. |title= Effects of ULF wave power on relativistic radiation belt electrons: 8-9 October 2012 geomagnetic storm | journal=Journal of Geophysical Research: Space Physics|date=2016-11-21|volume=121|issue=12|doi=10.1002/2016JA023130|bibcode=2016JGRA..12111766P }}</ref>