Chaotic Enby: /* References */ forgor my brain
{{short description|Climate patterns of the moon Triton}}
[[File:Voyager 2 Triton 14bg r90ccw.jpg|thumb|upright=1.5|Triton's southern polar cap and dark plume streaks]]
The '''climate of Triton''' encompasses the atmospheric dynamics, weather, and long-term atmospheric trends of [[Neptune]]'s moon [[Triton (moon)|Triton]]. Although the [[atmosphere of Triton]] is rather thin, with a [[Atmospheric pressure|surface pressure]] of only {{convert|1.4|Pa|atm|sigfig=3|abbr=on}} at the time of ''[[Voyager 2]]''{{'}}s flyby<ref name="McKinnon2014"/>{{rp|page=873}} but heavily variable, it still drives active, global weather and climate cycles and heavily influences Triton's glacial activity.
Triton's climate is dominated by extreme [[season|seasonal]] fluctuations that induce global [[Volatile (astrogeology)|volatile]] transport between its polar caps, leading to variable atmospheric circulation. The atmosphere of Triton also supports the formation of [[haze|atmospheric haze]] and [[cloud]]s, both of which remain poorly-studied. While Triton's climate is similar to the [[climate of Pluto]], important differences separate the two, such as Triton's more chaotic climate cycles and colder atmosphere.
== Atmospheric properties ==
{{main|Atmosphere of Triton}}
[[Atmosphere of Triton|Triton's atmosphere]] possesses a [[Atmospheric pressure|mean surface pressure]] of roughly 1.4 Pa, or roughly {{frac|70,000}} that of Earth's sea level pressure.<ref name="McKinnon2014"/> The mean surface pressure varies significantly with respect to Triton's [[season]]s; by 1997, Triton's atmospheric surface pressure had risen to approximately 1.9{{+-|0.18|0.15}} Pa<ref name="Elliot2000"/> and the surface pressure may have reached a maximum of roughly 4 Pa by 2010 (though there were no direct measurements via [[occultation]] between 2007 and 2017).<ref name="Lellouch2010"/><ref name="Sicardy2024"/> Nevertheless, by 2022 the surface pressure dropped back to 1.454 ± 0.047 Pa, nearly exactly what ''[[Voyager 2]]'' recorded in 1989.<ref name="Sicardy2024"/> Triton's atmosphere is composed mainly of nitrogen (~99%), with minor contributions from other compounds such as [[methane]] (~0.02%) and [[carbon monoxide]] (~0.01%), similar to the [[atmosphere of Pluto]] and, to an extent, the [[atmosphere of Titan]].<ref name="Lellouch2010"/><ref name="Ohno2021"/>
=== Temperature ===
Measurements of Triton's surface temperature by ''Voyager 2'' range between 34 and 44K (−239 and −229°C), with an extrapolated surface temperature of 37.5K (−235.7°C) based on an atmospheric thermal profile. These measurements are consistent with the observed atmospheric surface pressure of ~1.4 Pa by ''Voyager 2'', which is close to nitrogen's [[vapor pressure]] at 37.5K.<ref name="Nelson1990"/> Over the decade following the ''Voyager 2'' flyby, Triton's surface temperature increased to 39.3K (−233.9°C) by 1997.<ref name="Elliot1998"/>
== Atmospheric phenomena ==
[[File:The_Horns_of_Triton_-_Voyager_2_(43407605905).png|thumb|upright=1.5|Departure image of Triton and its atmosphere, with haze lit up by sunlight faintly visible just over Triton's surface]]
Despite the thin and heavily variable atmospheric surface pressure, Triton's atmosphere hosts a variety of global phenomena. Triton appears to host a distinct [[troposphere]], which may be thermally-defined by the atmosphere's vertical temperature profile.<ref name="Yelle1995"/> Alternatively, Triton's lower atmosphere may be dynamically-defined by [[wind shear]].<ref name="Zalucha2013"/>
=== Winds and circulation ===
Most information about Triton's winds come from the numerous dark streaks which mark its southern polar cap that appear to follow prevailing winds in the region. Over 100 of these streaks have been observed, with most extending to the northeast from narrow points—presumably their points of origin. Two active plumes, the Hili and Mahilani Plumes, were also observed; the plume columns abruptly streak westward at an altitude of roughly 8 km, possibly marking Triton's tropopause.<ref name="McKinnon2014"/>{{rp|page=873}} The direction of the plume streaks may indicate [[anticyclone|anticyclonic]] circulation around Triton's south pole, with winds blowing within an [[Ekman layer]] where wind direction is governed by a balance of the [[pressure gradient force]], [[Coriolis force]], and [[drag (physics)|drag]].<ref name="Zalucha2013"/> A temperature gradient drives a thermal wind which eventually weakens eastwards winds before reversing direction with increasing altitude.<ref name="McKinnon2014"/>{{rp|page=874}} The observations of the active plume columns show that Triton's atmosphere is capable of [[aeolian processes|wind-driven material transport]], but the speed of Triton's winds are poorly constrained. Early estimates shortly after the ''Voyager 2'' flyby estimated westerly wind speeds of 5-15 m/s near Triton's south pole, but subsequent modelling resulted in much weaker westerly winds of < 0.5 m/s.<ref name="Zalucha2013"/>
Triton's atmospheric circulation is dominated by the sublimation and deposition of nitrogen. Models of Triton's global circulation during its southern hemisphere summer, where nitrogen sublimates from the southern polar cap and deposits on the northern polar cap, result in a general south-to-north flow. The Coriolis force deflects these winds, leading to retrograde winds that blow up to 10 m/s above Triton's equator. However, the apparent reversal of winds ~8 km above Triton's south polar cap, as indicated by the plumes observed by ''Voyager 2'', remains largely unexplained.<ref name="Bertrand2019EPSC"/>
=== Clouds ===
Images of Triton's limb and terminator by ''Voyager 2'' discovered multiple clouds. Distinct, east-to-west crescent-shaped clouds roughly 10 km wide and hundreds of kilometers long were observed beyond Triton's terminator, with the clouds estimated to be 1-3 kilometers above the surface. Up to one-third of Triton's limb near its southern regions were covered by clouds. The clouds on Triton are likely composed of condensed nitrogen crystals suspended in Triton's atmosphere.<ref name="McKinnon2014"/>{{rp|page=873}}
=== Haze ===
As with the atmospheres of Pluto and Titan, Triton's atmosphere supports layers of organic atmospheric haze. The haze is relatively sparse; Triton's atmosphere is about as hazy as the Martian atmosphere when there are no dust storms are in progress.
<ref name="Cruikshank1989"/> The haze primarily occurs in Triton's lower atmosphere, extending up to ~30 km above Triton's surface, though possibly extending further, due to ''Voyager 2''{{'}}s detection limitations.<ref name="Ohno2021"/> The haze is likely formed by the action of [[ultraviolet]] light on atmospheric methane and nitrogen,<ref name="Moran2022"/><ref name="McKinnon2014"/>{{rp|page=873}} and may be influenced by the presence of carbon monoxide<ref name="Moran2022"/> the condensation of hydrocarbon ice.<ref name="Ohno2021"/> The resulting material aggregates into particles about 100-200 nm in size, largely composed of a variety of hydrocarbons and nitriles termed [[tholin]]s.<ref name="Moran2022"/><ref name="McKinnon2014"/>{{rp|page=873}} Despite the broad similarities between the atmospheres of Triton and Pluto in composition and pressure, models of haze formation indicate that the atmospheric haze on Triton significantly differs from the atmospheric haze of Pluto. This may be due to Triton's lower atmosphere being significantly colder than Pluto's atmosphere by 20-40K, alongside differences in methane abundance in the upper atmospheres of each.<ref name="Ohno2021"/>
== Seasons ==
[[File:Small_section_of_Triton.png|thumb|upright=1.5|Dark plume fans on Triton's southern ice cap, possibly from seasonally-driven geysers powered by prolonged heating from the southern summer Sun]]
Triton's seasons are very long, owing to Neptune's orbital period of 164.8 years. Neptune's orbit is also nearly circular, with a low eccentricity of 0.0097;<ref name="NeptuneFactSheet"/> as such, each season on Triton lasts roughly 40 years, and Triton's seasonal variations are almost entirely governed by the tilt of its rotational axis relative to the Sun.<ref name="Trafton1984"/>{{efn|Assuming that every season is equal in length, the season length is given by dividing the orbital period by four.}} Triton is [[tidally locked]], with one hemisphere facing Neptune at all times; Triton's rotational period is 5 days and 21 hours and it has nearly zero axial tilt with respect to its orbital plane around Neptune.<ref name="McKinnon2014"/>{{rp|page=866}} However, Triton's orbit is retrograde and significantly inclined with respect to Neptune's equatory, at roughly 23°, and Neptune itself has an axial tilt of roughly 28°.<ref name="Bertrand2022"/> Triton's orbit also experiences rapid [[precession]], with a nodal precession period of 637 ± 40 years.<ref name="Trafton1984"/> The combination of these factors results in complex seasonal cycles which vary significantly between each Neptune year, with its summer solstice subsolar latitude varying between 5° latitude to 50° latitude over a 140-180 year period.<ref name="Bertrand2022"/>
Similar to the [[climate of Pluto#Characteristics and climate zones|seasons of Pluto]] (and, to a lesser extent, the [[climate of Mars#Seasons|seasons of Mars]]), Triton's seasons strongly affect its volatile cycles and [[solid nitrogen|nitrogen ice]] caps. Triton's volatile cycles are largely controlled by the [[sublimation (phase transition)|sublimation]] and [[deposition (phase transition)|deposition]] of nitrogen and other volatile compounds.<ref name="BrownRH1994"/> Freshly-deposited nitrogen is expected to be bright as observed in Triton's southern polar cap and the bright, blue equatorial surface frost observed by ''Voyager 2''.<ref name="Bertrand2022"/> However, despite large regions of Triton being comparatively darker, ground-based spectral observations indicate that Triton's surface is mostly covered in a layer of transparent or translucent nitrogen ice; furthermore, modelling fails to replicate the observed distribution of bright and dark surfaces.<ref name="Duxburyetal1993"/> It has been suggested that small, freshly-deposited grains of nitrogen ice eventually metamorphize into a clear, transparent layer within a Triton season.<ref name="Bertrand2022"/> Conversely, freshly-deposited nitrogen ice may be translucent, before later shattering as seasonal swings in temperature induce repeated phase changes between solid nitrogen's α- and β-[[phase (matter)#Crystal phases|phases]], brightening older ice.<ref name="Duxburyetal1993"/>
At the time of ''Voyager 2''{{'}}s arrival, Triton was experiencing an unusually intense southern hemisphere summer. Triton's southern polar cap extended nearly or entirely up to the equator, covering large swathes of Triton's lower latitudes.<ref name="BrownRH1994"/> To extend so far indicates that Triton's southern polar cap likely maintains a large, permanent sheet of nitrogen ice (as opposed to completely seasonal polar caps). Triton's northern polar cap was not observed directly, but it is presumed to exist, albeit at a significantly smaller extent than Triton's southern cap. Modelling of Triton's seasonal cycles support the existence of a permanent northern polar cap with a thickness of at least several hundred meters, and that Triton's southern polar cap is likely to be over a kilometer thick at its maximum.<ref name="Bertrand2022"/>
The extreme southern hemisphere summer which coincided with the ''Voyager 2'' flyby may have contributed to the significant increase in surface temperature and atmospheric surface pressure observed from 1989 to 1997;<ref name="Elliot1998"/> this increase in atmospheric surface pressure continued until at least 2007, before returning to ''Voyager 2'' levels by 2017.<ref name="Lellouch2010"/><ref name="Sicardy2024"/> Climate models predicted a steady decrease in atmospheric pressure through 2005-2060 as sublimated nitrogen from the southern polar cap migrates to and deposits in the expanding northern polar cap, so the causes of the rapid fluctuations in pressure remain unclear.<ref name="Sicardy2024"/>
==See also==
* {{annotated link|Climate of Pluto}}
* {{annotated link|Climate of Mars}}
== Notes ==
{{Noteslist}}
== References ==
{{reflist
|refs=
<ref name="Elliot1998">{{cite journal| title=Global warming on Triton | url=http://occult.mit.edu/_assets/documents/publications/Elliot1998Nature393.766.pdf | last=Elliot | first=J.L. |author2=Hammel, H.B. |author3=Wasserman, L.H. | journal=[[Nature (journal)|Nature]] |volume=393 |date=1998| issue=6687 |pages=765–767 |doi=10.1038/31651 |bibcode=1998Natur.393..765E | s2cid=40865426 |display-authors=etal}}</ref>
<ref name="Nelson1990">{{cite journal |first1=Nelson |last1=R. M. |last2=Smythe |first2=W. D. |last3=Wallis |first3=B. D. |last4=Horn |first4=L. J. |last5=Lane |first5=A. L. |last6=Mayo |first6=M. J. |title=Temperature and Thermal Emissivity of the Surface of Neptune's Satellite Triton |journal=Science |date=October 1990 |volume=250 |issue=4979 |pages=429–31 |doi=10.1126/science.250.4979.429 |pmid=17793020 |bibcode=1990Sci...250..429N|s2cid=20022185 }}</ref>
<ref name="Sicardy2024">{{cite journal |last1=Sicardy |first1=B. |last2=Tej |first2=A. |last3=Gomez-Júnior |first3=A. R. |display-authors=et al. |title=Constraints on the evolution of the Triton atmosphere from occultations: 1989-2022 |journal=Astronomy & Astrophysics |date=February 2024 |volume=682 |pages=8 |doi=10.1051/0004-6361/202348756 |bibcode=2024A&A...682L..24S }}</ref>
<ref name="Elliot2000">{{cite journal|first1=J.L.|last1=Elliot|last2=Strobel|first2=D.F.|first3=X.|last3=Zhu|title=The Thermal Structure of Triton's Middle Atmosphere |journal=Icarus |volume=143 |issue=2 |pages=425–428 |doi=10.1006/icar.1999.6312 |url=http://occult.mit.edu/_assets/documents/publications/Elliot2000Icarus143.425.pdf |date=2000 |bibcode=2000Icar..143..425E |display-authors=etal}}</ref>
<ref name="Moran2022">{{Cite journal |last1=Moran |first1=Sarah E. |last2=Hörst |first2=Sarah M. |last3=He |first3=Chao |last4=Radke |first4=Michael J. |last5=Sebree |first5=Joshua A. |last6=Izenberg |first6=Noam R. |last7=Vuitton |first7=Véronique |last8=Flandinet |first8=Laurène |last9=Orthous-Daunay |first9=François-Régis |last10=Wolters |first10=Cédric |date=January 2022 |title=Triton Haze Analogs: The Role of Carbon Monoxide in Haze Formation |journal=Journal of Geophysical Research: Planets |language=en |volume=127 |issue=1 |doi=10.1029/2021JE006984 |arxiv=2112.11627 |bibcode=2022JGRE..12706984M |s2cid=245385730 |issn=2169-9097|doi-access=free }}</ref>
<ref name=Lellouch2010>{{cite journal|last1=Lellouch|first1=E. |last2=de Bergh|first2=C.|last3=Sicardy|first3=B.|title=Detection of CO in Triton's atmosphere and the nature of surface-atmosphere interactions|date=2010|journal=Astronomy and Astrophysics|volume=512|pages=L8|doi=10.1051/0004-6361/201014339|bibcode=2010A&A...512L...8L|arxiv = 1003.2866 |s2cid=58889896 |display-authors=etal}}</ref>
<ref name="McKinnon2014">{{cite book |last1=McKinnon |first1=William B. |last2=Kirk |first2=Randloph L. |date=2014 |title=Encyclopedia of the Solar System |edition=Third |url=https://www.sciencedirect.com/book/9780124158450/encyclopedia-of-the-solar-system |access-date=15 April 2024 |publisher= |doi=10.1016/C2010-0-67309-3 |isbn=978-0-12-415845-0}}</ref>
<ref name="Cruikshank1989">{{Cite journal |last1=Cruikshank |first1=D. P. |last2=Brown |first2=R. H. |last3=Giver |first3=L. P. |last4=Tokunaga |first4=A. T. |date=February 2022 |title=Triton: Do We See to the Surface? |journal=Science |volume=245 |issue=4915 |pages=283-286 |bibcode=1989Sci...245..283C |doi=10.1126/science.245.4915.283 |url=https://www.science.org/doi/10.1126/science.245.4915.283 |access-date=15 April 2024 }}</ref>
<ref name="Ohno2021">{{Cite journal |last1=Ohno |first1=Kazumasa |last2=Zhang |first2=Xi |last3=Tazaki |first3=Ryo |last4=Okuzumi |first4=Satoshi |date=May 2021 |title=Haze Formation on Triton |journal=The Astrophysical Journal |language=en |volume=912 |issue=1 |page=37 |doi=10.3847/1538-4357/abee82 |doi-access=free |arxiv=2012.11932 |bibcode=2021ApJ...912...37O }}</ref>
<ref name="Bertrand2022">{{Cite journal |last1=Bertrand |first1=T. |last2=Lellouch |first2=E. |last3=Holler |first3=B. J. |display-authors=etal |date=February 2022 |title=Volatile transport modeling on Triton with new observational constraints |url=https://www.sciencedirect.com/science/article/pii/S0019103521004164 |journal=Icarus|volume=373 |bibcode=2022Icar..37314764B |doi=10.1016/j.icarus.2021.114764 |access-date=15 April 2024 }}</ref>
<ref name="Trafton1984">{{Cite journal |last1=Trafton |first1=L. |date=May 1984 |title=Large seasonal variations in Triton's atmosphere |journal=Icarus |volume=58 |issue=2 |pages=312-324 |bibcode=1984Icar...58..312T |doi=10.1016/0019-1035(84)90048-4
}}</ref>
<ref name="Bertrand2019EPSC">{{cite conference |url=https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-376-1.pdf |title=Climate modeling on Triton with a hierarchy of models |access-date=16 April 2024 |last1=Bertrand |first1=Tanguy |last2=Forget |first2=François |last3=Sicardy |first3=Bruno |display-authors=et al. |date=September 2019 |pages=EPSC-DPS2019-376 conference=EPSC-DPS Joint Meeting 2019 |location=Geneva, Switzerland |bibcode=2019EPSC...13..376B }}</ref>
<ref name="NeptuneFactSheet">{{cite web |last=Williams |first=David R. |date=1 September 2004 |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html |title=Neptune Fact Sheet |publisher=NASA |access-date=14 August 2007 |archive-url=https://web.archive.org/web/2010070...nasa.gov/planetary/factsheet/neptunefact.html |archive-date=1 July 2010 |url-status=live }}</ref>
<ref name="BrownRH1994">{{Cite journal |last1=Brown |first1=Robert H. |last2=Kirk |first2=Randolph L. |date=January 1994 |title=Coupling of volatile transport and internal heat flow on Triton |journal=Journal of Geophysical Research |volume=99 |issue=E1 |pages=1965-1982 |bibcode=1994JGR....99.1965B |doi=10.1029/93JE02618 }}</ref>
<ref name="Duxburyetal1993">
{{cite journal
| title = The Phase Composition of Triton's Polar Caps
| bibcode = 1993Sci...261..748D
| author = Duxbury, N S |author2 = Brown, R H
| journal = Science
| volume = 261
| issue = 5122
| pages = 748–751
|date=August 1993
| doi = 10.1126/science.261.5122.748
| pmid = 17757213
| s2cid = 19761107
}}
</ref>
<ref name="Yelle1995">
{{cite journal |title=Lower atmospheric structure and surface-atmosphere interactions on Triton |date=1995 |last1=Yelle |first1=R. V. |last2=Lunine |first2=J. I. |last3=Pollack |first3=J. B. |last4=Brown |first4=R. H. |journal=Neptune and Triton |volume= |issue= |pages=1031 - 1105 |doi= |bibcode=1995netr.conf.1031Y }}</ref>
<ref name="Zalucha2013">
{{cite journal |title=A 3D general circulation model for Pluto and Triton with fixed volatile abundance and simplified surface forcing |date=April 2013 |last1=Zalucha |first1=Angela M. |last2=Michaels |first2=Timothy I. |journal=Icarus |volume=223 |issue=2 |pages=819-831 |doi=10.1016/j.icarus.2013.01.026 |bibcode=2013Icar..223..819Z }}</ref>
}} <!-- end of reflist -->
{{Moons of Neptune}}
[[Category:Triton (moon)]]
[[Category:Climates of the Solar System|Triton]]
Okumaya devam et...
{{short description|Climate patterns of the moon Triton}}
[[File:Voyager 2 Triton 14bg r90ccw.jpg|thumb|upright=1.5|Triton's southern polar cap and dark plume streaks]]
The '''climate of Triton''' encompasses the atmospheric dynamics, weather, and long-term atmospheric trends of [[Neptune]]'s moon [[Triton (moon)|Triton]]. Although the [[atmosphere of Triton]] is rather thin, with a [[Atmospheric pressure|surface pressure]] of only {{convert|1.4|Pa|atm|sigfig=3|abbr=on}} at the time of ''[[Voyager 2]]''{{'}}s flyby<ref name="McKinnon2014"/>{{rp|page=873}} but heavily variable, it still drives active, global weather and climate cycles and heavily influences Triton's glacial activity.
Triton's climate is dominated by extreme [[season|seasonal]] fluctuations that induce global [[Volatile (astrogeology)|volatile]] transport between its polar caps, leading to variable atmospheric circulation. The atmosphere of Triton also supports the formation of [[haze|atmospheric haze]] and [[cloud]]s, both of which remain poorly-studied. While Triton's climate is similar to the [[climate of Pluto]], important differences separate the two, such as Triton's more chaotic climate cycles and colder atmosphere.
== Atmospheric properties ==
{{main|Atmosphere of Triton}}
[[Atmosphere of Triton|Triton's atmosphere]] possesses a [[Atmospheric pressure|mean surface pressure]] of roughly 1.4 Pa, or roughly {{frac|70,000}} that of Earth's sea level pressure.<ref name="McKinnon2014"/> The mean surface pressure varies significantly with respect to Triton's [[season]]s; by 1997, Triton's atmospheric surface pressure had risen to approximately 1.9{{+-|0.18|0.15}} Pa<ref name="Elliot2000"/> and the surface pressure may have reached a maximum of roughly 4 Pa by 2010 (though there were no direct measurements via [[occultation]] between 2007 and 2017).<ref name="Lellouch2010"/><ref name="Sicardy2024"/> Nevertheless, by 2022 the surface pressure dropped back to 1.454 ± 0.047 Pa, nearly exactly what ''[[Voyager 2]]'' recorded in 1989.<ref name="Sicardy2024"/> Triton's atmosphere is composed mainly of nitrogen (~99%), with minor contributions from other compounds such as [[methane]] (~0.02%) and [[carbon monoxide]] (~0.01%), similar to the [[atmosphere of Pluto]] and, to an extent, the [[atmosphere of Titan]].<ref name="Lellouch2010"/><ref name="Ohno2021"/>
=== Temperature ===
Measurements of Triton's surface temperature by ''Voyager 2'' range between 34 and 44K (−239 and −229°C), with an extrapolated surface temperature of 37.5K (−235.7°C) based on an atmospheric thermal profile. These measurements are consistent with the observed atmospheric surface pressure of ~1.4 Pa by ''Voyager 2'', which is close to nitrogen's [[vapor pressure]] at 37.5K.<ref name="Nelson1990"/> Over the decade following the ''Voyager 2'' flyby, Triton's surface temperature increased to 39.3K (−233.9°C) by 1997.<ref name="Elliot1998"/>
== Atmospheric phenomena ==
[[File:The_Horns_of_Triton_-_Voyager_2_(43407605905).png|thumb|upright=1.5|Departure image of Triton and its atmosphere, with haze lit up by sunlight faintly visible just over Triton's surface]]
Despite the thin and heavily variable atmospheric surface pressure, Triton's atmosphere hosts a variety of global phenomena. Triton appears to host a distinct [[troposphere]], which may be thermally-defined by the atmosphere's vertical temperature profile.<ref name="Yelle1995"/> Alternatively, Triton's lower atmosphere may be dynamically-defined by [[wind shear]].<ref name="Zalucha2013"/>
=== Winds and circulation ===
Most information about Triton's winds come from the numerous dark streaks which mark its southern polar cap that appear to follow prevailing winds in the region. Over 100 of these streaks have been observed, with most extending to the northeast from narrow points—presumably their points of origin. Two active plumes, the Hili and Mahilani Plumes, were also observed; the plume columns abruptly streak westward at an altitude of roughly 8 km, possibly marking Triton's tropopause.<ref name="McKinnon2014"/>{{rp|page=873}} The direction of the plume streaks may indicate [[anticyclone|anticyclonic]] circulation around Triton's south pole, with winds blowing within an [[Ekman layer]] where wind direction is governed by a balance of the [[pressure gradient force]], [[Coriolis force]], and [[drag (physics)|drag]].<ref name="Zalucha2013"/> A temperature gradient drives a thermal wind which eventually weakens eastwards winds before reversing direction with increasing altitude.<ref name="McKinnon2014"/>{{rp|page=874}} The observations of the active plume columns show that Triton's atmosphere is capable of [[aeolian processes|wind-driven material transport]], but the speed of Triton's winds are poorly constrained. Early estimates shortly after the ''Voyager 2'' flyby estimated westerly wind speeds of 5-15 m/s near Triton's south pole, but subsequent modelling resulted in much weaker westerly winds of < 0.5 m/s.<ref name="Zalucha2013"/>
Triton's atmospheric circulation is dominated by the sublimation and deposition of nitrogen. Models of Triton's global circulation during its southern hemisphere summer, where nitrogen sublimates from the southern polar cap and deposits on the northern polar cap, result in a general south-to-north flow. The Coriolis force deflects these winds, leading to retrograde winds that blow up to 10 m/s above Triton's equator. However, the apparent reversal of winds ~8 km above Triton's south polar cap, as indicated by the plumes observed by ''Voyager 2'', remains largely unexplained.<ref name="Bertrand2019EPSC"/>
=== Clouds ===
Images of Triton's limb and terminator by ''Voyager 2'' discovered multiple clouds. Distinct, east-to-west crescent-shaped clouds roughly 10 km wide and hundreds of kilometers long were observed beyond Triton's terminator, with the clouds estimated to be 1-3 kilometers above the surface. Up to one-third of Triton's limb near its southern regions were covered by clouds. The clouds on Triton are likely composed of condensed nitrogen crystals suspended in Triton's atmosphere.<ref name="McKinnon2014"/>{{rp|page=873}}
=== Haze ===
As with the atmospheres of Pluto and Titan, Triton's atmosphere supports layers of organic atmospheric haze. The haze is relatively sparse; Triton's atmosphere is about as hazy as the Martian atmosphere when there are no dust storms are in progress.
<ref name="Cruikshank1989"/> The haze primarily occurs in Triton's lower atmosphere, extending up to ~30 km above Triton's surface, though possibly extending further, due to ''Voyager 2''{{'}}s detection limitations.<ref name="Ohno2021"/> The haze is likely formed by the action of [[ultraviolet]] light on atmospheric methane and nitrogen,<ref name="Moran2022"/><ref name="McKinnon2014"/>{{rp|page=873}} and may be influenced by the presence of carbon monoxide<ref name="Moran2022"/> the condensation of hydrocarbon ice.<ref name="Ohno2021"/> The resulting material aggregates into particles about 100-200 nm in size, largely composed of a variety of hydrocarbons and nitriles termed [[tholin]]s.<ref name="Moran2022"/><ref name="McKinnon2014"/>{{rp|page=873}} Despite the broad similarities between the atmospheres of Triton and Pluto in composition and pressure, models of haze formation indicate that the atmospheric haze on Triton significantly differs from the atmospheric haze of Pluto. This may be due to Triton's lower atmosphere being significantly colder than Pluto's atmosphere by 20-40K, alongside differences in methane abundance in the upper atmospheres of each.<ref name="Ohno2021"/>
== Seasons ==
[[File:Small_section_of_Triton.png|thumb|upright=1.5|Dark plume fans on Triton's southern ice cap, possibly from seasonally-driven geysers powered by prolonged heating from the southern summer Sun]]
Triton's seasons are very long, owing to Neptune's orbital period of 164.8 years. Neptune's orbit is also nearly circular, with a low eccentricity of 0.0097;<ref name="NeptuneFactSheet"/> as such, each season on Triton lasts roughly 40 years, and Triton's seasonal variations are almost entirely governed by the tilt of its rotational axis relative to the Sun.<ref name="Trafton1984"/>{{efn|Assuming that every season is equal in length, the season length is given by dividing the orbital period by four.}} Triton is [[tidally locked]], with one hemisphere facing Neptune at all times; Triton's rotational period is 5 days and 21 hours and it has nearly zero axial tilt with respect to its orbital plane around Neptune.<ref name="McKinnon2014"/>{{rp|page=866}} However, Triton's orbit is retrograde and significantly inclined with respect to Neptune's equatory, at roughly 23°, and Neptune itself has an axial tilt of roughly 28°.<ref name="Bertrand2022"/> Triton's orbit also experiences rapid [[precession]], with a nodal precession period of 637 ± 40 years.<ref name="Trafton1984"/> The combination of these factors results in complex seasonal cycles which vary significantly between each Neptune year, with its summer solstice subsolar latitude varying between 5° latitude to 50° latitude over a 140-180 year period.<ref name="Bertrand2022"/>
Similar to the [[climate of Pluto#Characteristics and climate zones|seasons of Pluto]] (and, to a lesser extent, the [[climate of Mars#Seasons|seasons of Mars]]), Triton's seasons strongly affect its volatile cycles and [[solid nitrogen|nitrogen ice]] caps. Triton's volatile cycles are largely controlled by the [[sublimation (phase transition)|sublimation]] and [[deposition (phase transition)|deposition]] of nitrogen and other volatile compounds.<ref name="BrownRH1994"/> Freshly-deposited nitrogen is expected to be bright as observed in Triton's southern polar cap and the bright, blue equatorial surface frost observed by ''Voyager 2''.<ref name="Bertrand2022"/> However, despite large regions of Triton being comparatively darker, ground-based spectral observations indicate that Triton's surface is mostly covered in a layer of transparent or translucent nitrogen ice; furthermore, modelling fails to replicate the observed distribution of bright and dark surfaces.<ref name="Duxburyetal1993"/> It has been suggested that small, freshly-deposited grains of nitrogen ice eventually metamorphize into a clear, transparent layer within a Triton season.<ref name="Bertrand2022"/> Conversely, freshly-deposited nitrogen ice may be translucent, before later shattering as seasonal swings in temperature induce repeated phase changes between solid nitrogen's α- and β-[[phase (matter)#Crystal phases|phases]], brightening older ice.<ref name="Duxburyetal1993"/>
At the time of ''Voyager 2''{{'}}s arrival, Triton was experiencing an unusually intense southern hemisphere summer. Triton's southern polar cap extended nearly or entirely up to the equator, covering large swathes of Triton's lower latitudes.<ref name="BrownRH1994"/> To extend so far indicates that Triton's southern polar cap likely maintains a large, permanent sheet of nitrogen ice (as opposed to completely seasonal polar caps). Triton's northern polar cap was not observed directly, but it is presumed to exist, albeit at a significantly smaller extent than Triton's southern cap. Modelling of Triton's seasonal cycles support the existence of a permanent northern polar cap with a thickness of at least several hundred meters, and that Triton's southern polar cap is likely to be over a kilometer thick at its maximum.<ref name="Bertrand2022"/>
The extreme southern hemisphere summer which coincided with the ''Voyager 2'' flyby may have contributed to the significant increase in surface temperature and atmospheric surface pressure observed from 1989 to 1997;<ref name="Elliot1998"/> this increase in atmospheric surface pressure continued until at least 2007, before returning to ''Voyager 2'' levels by 2017.<ref name="Lellouch2010"/><ref name="Sicardy2024"/> Climate models predicted a steady decrease in atmospheric pressure through 2005-2060 as sublimated nitrogen from the southern polar cap migrates to and deposits in the expanding northern polar cap, so the causes of the rapid fluctuations in pressure remain unclear.<ref name="Sicardy2024"/>
==See also==
* {{annotated link|Climate of Pluto}}
* {{annotated link|Climate of Mars}}
== Notes ==
{{Noteslist}}
== References ==
{{reflist
|refs=
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<ref name="Trafton1984">{{Cite journal |last1=Trafton |first1=L. |date=May 1984 |title=Large seasonal variations in Triton's atmosphere |journal=Icarus |volume=58 |issue=2 |pages=312-324 |bibcode=1984Icar...58..312T |doi=10.1016/0019-1035(84)90048-4
}}</ref>
<ref name="Bertrand2019EPSC">{{cite conference |url=https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-376-1.pdf |title=Climate modeling on Triton with a hierarchy of models |access-date=16 April 2024 |last1=Bertrand |first1=Tanguy |last2=Forget |first2=François |last3=Sicardy |first3=Bruno |display-authors=et al. |date=September 2019 |pages=EPSC-DPS2019-376 conference=EPSC-DPS Joint Meeting 2019 |location=Geneva, Switzerland |bibcode=2019EPSC...13..376B }}</ref>
<ref name="NeptuneFactSheet">{{cite web |last=Williams |first=David R. |date=1 September 2004 |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html |title=Neptune Fact Sheet |publisher=NASA |access-date=14 August 2007 |archive-url=https://web.archive.org/web/2010070...nasa.gov/planetary/factsheet/neptunefact.html |archive-date=1 July 2010 |url-status=live }}</ref>
<ref name="BrownRH1994">{{Cite journal |last1=Brown |first1=Robert H. |last2=Kirk |first2=Randolph L. |date=January 1994 |title=Coupling of volatile transport and internal heat flow on Triton |journal=Journal of Geophysical Research |volume=99 |issue=E1 |pages=1965-1982 |bibcode=1994JGR....99.1965B |doi=10.1029/93JE02618 }}</ref>
<ref name="Duxburyetal1993">
{{cite journal
| title = The Phase Composition of Triton's Polar Caps
| bibcode = 1993Sci...261..748D
| author = Duxbury, N S |author2 = Brown, R H
| journal = Science
| volume = 261
| issue = 5122
| pages = 748–751
|date=August 1993
| doi = 10.1126/science.261.5122.748
| pmid = 17757213
| s2cid = 19761107
}}
</ref>
<ref name="Yelle1995">
{{cite journal |title=Lower atmospheric structure and surface-atmosphere interactions on Triton |date=1995 |last1=Yelle |first1=R. V. |last2=Lunine |first2=J. I. |last3=Pollack |first3=J. B. |last4=Brown |first4=R. H. |journal=Neptune and Triton |volume= |issue= |pages=1031 - 1105 |doi= |bibcode=1995netr.conf.1031Y }}</ref>
<ref name="Zalucha2013">
{{cite journal |title=A 3D general circulation model for Pluto and Triton with fixed volatile abundance and simplified surface forcing |date=April 2013 |last1=Zalucha |first1=Angela M. |last2=Michaels |first2=Timothy I. |journal=Icarus |volume=223 |issue=2 |pages=819-831 |doi=10.1016/j.icarus.2013.01.026 |bibcode=2013Icar..223..819Z }}</ref>
}} <!-- end of reflist -->
{{Moons of Neptune}}
[[Category:Triton (moon)]]
[[Category:Climates of the Solar System|Triton]]
Okumaya devam et...