Editing Meteor (section)

== Effect on atmosphere ==
{{redirect2|Ionization trail|Dark flight (astronomy)|the movie|Dark Flight}}
[[File:P10220XX.01.49.MESZ.14.08.2019.Berlin.Perseiden.x1.0.gif|thumb|A meteoroid of the [[Perseids]] with a size of about ten millimetres entering the earth's atmosphere in real time. The meteoroid is at the bright head of the trail, and the ionisation of the [[mesosphere]] is still visible in the tail.]]

The entry of meteoroids into Earth's atmosphere produces three main effects: ionization of atmospheric molecules, dust that the meteoroid sheds, and the sound of passage. During the entry of a meteoroid or asteroid into the [[upper atmosphere]], an '''ionization trail''' is created, where the air molecules are [[ionization|ionized]] by the passage of the meteor. Such ionization trails can last up to 45 minutes at a time.

Small, [[sand-grain]] sized meteoroids are entering the atmosphere constantly, essentially every few seconds in any given region of the atmosphere, and thus ionization trails can be found in the upper atmosphere more or less continuously. When radio waves are bounced off these trails, it is called [[meteor burst communications]]. Meteor radars can measure atmospheric density and winds by measuring the [[decay rate]] and [[Doppler shift]] of a meteor trail. Most meteoroids burn up when they enter the atmosphere. The left-over debris is called ''meteoric dust'' or just meteor dust. Meteor dust particles can persist in the atmosphere for up to several months. These particles might affect climate, both by scattering electromagnetic radiation and by catalyzing chemical reactions in the upper atmosphere.<ref name="Nature-443141a">{{cite journal |first=Jeff |last=Kanipe |title=Climate change: A cosmic connection |journal=Nature |volume=443 |issue=7108 |pages=141–143 |date=14 September 2006 |doi=10.1038/443141a |pmid=16971922 |bibcode=2006Natur.443..141K |s2cid=4400113 |doi-access=free }}</ref> Meteoroids or their fragments achieve '''dark flight''' after deceleration to [[terminal velocity]].<ref name="IMO-meteorites">{{cite web
  |title=Fireballs and Meteorite Falls
  |publisher=International Meteor Organization
  |url = http://www.imo.net/fireball/meteorites
  |access-date=2013-03-05 }}</ref> Dark flight starts when they decelerate to about {{convert|2|–|4|km/s|mph|abbr=on}}.
<ref name="AMS-Fireball">{{cite web
  |title=Fireball FAQS
  |publisher=American Meteor Society
  |url = http://www.amsmeteors.org/fireballs/faqf/#8
  |access-date=2013-03-05 }}</ref> Larger fragments fall further down the [[strewn field]].

=== Colours ===
[[File:Leonid Meteor.jpg|thumb|A meteor of the [[Leonid meteor shower]]; the photograph shows the meteor, afterglow, and wake as distinct components]]

The visible light produced by a meteor may take on various hues, depending on the chemical composition of the meteoroid, and the speed of its movement through the atmosphere. As layers of the meteoroid abrade and ionize, the colour of the light emitted may change according to the layering of minerals. Colours of meteors depend on the relative influence of the metallic content of the meteoroid versus the superheated air plasma, which its passage engenders:<ref>{{cite web| title = Background facts on meteors and meteor showers.
 | publisher = NASA
 | url = http://leonid.arc.nasa.gov/meteor.html
 | access-date = 2014-02-24}}
</ref>
* Orange-yellow ([[sodium]])
* Yellow ([[iron]])
* Blue-green ([[magnesium]])
* Violet ([[calcium]])
* Red (atmospheric [[nitrogen]] and [[oxygen]])

=== Acoustic manifestations ===
The sound generated by a meteor in the upper atmosphere, such as a [[sonic boom]], typically arrives many seconds after the visual light from a meteor disappears. Occasionally, as with the [[Leonid meteor shower]] of 2001, "crackling", "swishing", or "hissing" sounds have been reported,<ref name="find-87854873">{{cite news |url=http://findarticles.com/p/articles/mi_m1134/is_6_111/ai_87854873/pg_1 |work=Natural History |title=Psst! Sounds like a meteor: in the debate about whether or not meteors make noise, skeptics have had the upper hand until now |first=Alan |last=Burdick |year=2002 |archive-url=https://archive.today/20120715100344/http://findarticles.com/p/articles/mi_m1134/is_6_111/ai_87854873/pg_1 |archive-date=2012-07-15 }}</ref> occurring at the same instant as a meteor flare. These are sometimes called [[electrophonic sounds]].<ref>{{Cite journal |last1=Zgrablić |first1=Goran |last2=Vinković |first2=Dejan |last3=Gradečak |first3=Silvija |last4=Kovačić |first4=Damir |last5=Biliškov |first5=Nikola |last6=Grbac |first6=Neven |last7=Andreić |first7=Željko |last8=Garaj |first8=Slaven |date=2002 |title=Instrumental recording of electrophonic sounds from Leonid fireballs |url=https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2001JA000310 |journal=Journal of Geophysical Research: Space Physics |language=en |volume=107 |issue=A7 |pages=SIA 11–1–SIA 11-9 |doi=10.1029/2001JA000310 |bibcode=2002JGRA..107.1124Z |issn=2156-2202}}</ref> Similar sounds have also been reported during intense displays of Earth's [[Aurora (astronomy)|auroras]].<ref name="auroral-sounds">{{cite web |url=https://sites.google.com/site/auroralsound/ |first=Andris |last=Vaivads |year=2002 |title=Auroral Sounds |access-date=2011-02-27 }}</ref><ref name="auroral-acoustics">{{cite web |url=http://www.acoustics.hut.fi/projects/aurora/ |title=Auroral Acoustics |work=Laboratory of Acoustics and Audio Signal Processing, Helsinki University of Technology |access-date=2011-02-17 }}</ref><ref name="AG16-155">{{cite book |doi=10.1016/S0065-2687(08)60352-0 |first1=Sam M. |last1=Silverman |first2=Tai-Fu |last2=Tuan |year=1973 |title=Auroral Audibility |volume=16 |pages=155–259 |series=Advances in Geophysics |isbn=978-0-12-018816-1 |bibcode = 1973AdGeo..16..155S }}</ref><ref name="JRASC-373K">{{cite journal |first=Colin S. L. |last=Keay |year=1990 |title=C. A. Chant and the Mystery of Auroral Sounds |journal=Journal of the Royal Astronomical Society of Canada |volume=84 |pages=373–382 |bibcode=  1990JRASC..84..373K}}</ref> 

Theories on the generation of these sounds may partially explain them. For example, scientists at NASA suggested that the turbulent ionized wake of a meteor interacts with [[geomagnetic field|Earth's magnetic field]], generating pulses of [[radio wave]]s. As the trail dissipates, [[megawatt]]s of electromagnetic power could be released, with a peak in the [[power spectrum]] at [[audio frequencies]]. Physical [[vibration]]s induced by the electromagnetic impulses would then be heard if they are powerful enough to make grasses, plants, eyeglass frames, the hearer's own body (see [[microwave auditory effect]]), and other conductive materials vibrate.<ref name="NASA-ast26">{{cite web |url=https://science.nasa.gov/headlines/y2001/ast26nov_1.htm |title=Listening to Leonids |publisher=science.nasa.gov |access-date=2011-09-16 |archive-url=https://web.archive.org/web/20090908035648/http://science.nasa.gov/headlines/y2001/ast26nov_1.htm |archive-date=2009-09-08 }}</ref><ref>{{cite journal |last1=Sommer |first1=H. C. |last2=Von Gierke |first2=H. E. |title=Hearing sensations in electric fields |journal=Aerospace Medicine |date=September 1964 |volume=35 |pages=834–839 |pmid=14175790 }} [https://web.archive.org/web/20110629080138/http://homepages.tesco.net/~John.Dawes2/extract.htm Extract text archive.]</ref><ref>{{cite journal |last1=Frey |first1=Allan H. |title=Human auditory system response to modulated electromagnetic energy |journal=Journal of Applied Physiology |date=1 July 1962 |volume=17 |issue=4 |pages=689–692 |doi=10.1152/jappl.1962.17.4.689 |pmid=13895081 |s2cid=12359057 }} [https://web.archive.org/web/20110629121952/http://homepages.tesco.net/~John.Dawes2/frey.htm Full text archive.]</ref><ref>{{cite journal |last1=Frey |first1=Allan H. |last2=Messenger |first2=Rodman |title=Human Perception of Illumination with Pulsed Ultrahigh-Frequency Electromagnetic Energy |journal=Science |date=27 Jul 1973 |volume=181 |issue=4097 |pages=356–358 |doi=10.1126/science.181.4097.356 |pmid=4719908 |bibcode = 1973Sci...181..356F |s2cid=31038030 }} [https://web.archive.org/web/20110629122016/http://homepages.tesco.net/~John.Dawes2/frey2.htm Full text archive.]</ref> This proposed mechanism, although proven plausible by laboratory work, remains unsupported by corresponding measurements in the field. Sound recordings made under controlled conditions in Mongolia in 1998 support the contention that the sounds are real.<ref name="BBC-321596">{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/321596.stm |title=Sound of shooting stars |work=BBC News |first=Chris |last=Riley |date=1999-04-21 |access-date=2011-09-16 }}</ref> ''(Also see [[Bolide]].)''