Editing Orography

{{Short description|Study of the topographic relief of mountains}}
{{Use dmy dates|date=April 2017}}
[[File:Map of Eastern Siberia.png|thumbnail|An orographic map of Eastern [[Siberia]] from 1875 by [[Peter Kropotkin]]]]

'''Orography''' is the study of the [[topographic relief]] of [[mountains]],<ref>{{Cite EB1911|wstitle=Orography|short=x}}</ref> and can more broadly include hills, and any part of a region's elevated terrain.<ref>[http://amsglossary.allenpress.com/glossary/search?p=1&query=Orography&submit=Search Orography] ({{Webarchive|url=https://web.archive.org/web/20070927214627/http://amsglossary.allenpress.com/glossary/search?p=1&query=Orography&submit=Search |date=27 September 2007 }}). [[American Meteorological Society]].</ref> Orography (also known as ''oreography'', ''orology,'' or ''oreology'') falls within the broader discipline of [[geomorphology]].<ref name=WDL1>{{cite web|title=Map of the Southern Half of Eastern Siberia and Parts of Mongolia, Manchuria, and Sakhalin: For a General Sketch of the Orography of Eastern Siberia|url=http://www.wdl.org/en/item/125/|publisher=World Digital Library|access-date=23 January 2013}}</ref> The term orography comes from the [[Ancient Greek|Greek]]: {{lang|grc|όρος}}, hill, {{lang|grc|γράφω}}, to write.

==Uses==
Mountain ranges and elevated land masses have a major impact on [[global climate]]. For instance, the elevated areas of [[East Africa]] substantially determine the strength of the [[Monsoons#Northern Indian Ocean Monsoon|Indian monsoon]].<ref>Srinivasan, J., Nanjundiah, Ravi S. and Chakraborty, Arindam (2005). [http://hdl.handle.net/2005/76 "Impact of Orography on the Simulation of Monsoon Climate in a General Circulation Model"]. Indian Institute of Science.</ref> In scientific models, such as [[general circulation model]]s, orography defines the lower boundary of the model over land.{{Citation needed|date=January 2009}}

When a river's [[tributaries]] or settlements by the river are listed in 'orographic sequence', they are in order from the highest (nearest the source of the river) to the lowest or [[mainstem (hydrology)|mainstem]] (nearest the mouth).{{Citation needed|date=January 2009}} This method of listing tributaries is similar to the [[Strahler Stream Order]], where the headwater tributaries are listed as category&nbsp;1.

==Orographic precipitation==
{{See also|Orographic lift}}
{{Split|Orographic precipitation|date=November 2020|discuss=Talk:Orography#Splitting proposal|section=y}}
[[Image:Steigungsregen.jpg|thumb|right|Orographic precipitation occurs when moist air is forced upwards by terrain.]]
Orographic precipitation, also known as relief precipitation, is [[precipitation (meteorology)|precipitation]] generated by a forced upward movement of air upon encountering a physiographic upland (see [[anabatic wind]]). This lifting can be caused by:

# Upward deflection of large-scale horizontal flow by the orography.
# Anabatic or upward vertical propagation of moist air up an orographic slope, caused by daytime heating of the mountain barrier surface.

Upon ascent, the air that is being lifted expands and cools adiabatically. This [[Adiabatic lapse rate|adiabatic cooling]] of a rising moist air parcel may lower its temperature to its [[dew point]], thus allowing for condensation of the water vapor contained within it, and hence the formation of a [[cloud]]. If enough water vapor condenses into cloud droplets, these droplets may become large enough to fall to the ground as precipitation.

[[Terrain|Terrain-induced]] precipitation is a major factor for [[meteorologists]] to consider when they forecast the local weather. Orography can play a major role in determining the type, amount, intensity, and duration of precipitation events. Researchers have discovered that barrier width, slope steepness, and [[updraft]] speed are major contributors when it comes to achieving the optimal amount and intensity of orographic precipitation. [[Computer model]]s simulating these factors have shown that narrow barriers and steeper slopes produce stronger updraft speeds, which in turn increase orographic precipitation.

Orographic precipitation is known to occur on oceanic [[island]]s, such as the [[Hawaiian Islands]] and [[New Zealand]]; much of the rainfall received on such islands is on the windward side, and the [[leeward]] side tends to be quite dry, almost [[desert]]-like. This phenomenon results in substantial local gradients in the amount of average rainfall, with coastal areas receiving on the order of {{convert|20|to|30|in|mm}} per year, and interior uplands receiving over {{convert|100|in|mm}} per year. Leeward coastal areas are especially dry&mdash;less than {{convert|20|in|mm|abbr=on}} per year at [[Waikiki]]&mdash;and the tops of moderately high uplands are especially wet&mdash;about {{convert|475|in|mm|abbr=on}} per year at [[Wai'ale'ale]] on [[Kaua'i]].

Another area in which orographic precipitation is known to occur is the [[Pennines]] in the north of [[England]]: the west side of the Pennines receives more rain than the east because the clouds are forced up and over the hills and cause the rain to tend to fall on the western slopes. This is particularly noticeable between [[Manchester]] (to the west) and [[Leeds]] (to the east); Leeds receives less rain due to a rain shadow of {{convert|12|mi}} from the Pennines.

==See also==
* [[Coverage (telecommunication)]]
* [[Orographic lift]]
* [[Rain shadow]]

== Citations ==
{{Reflist}}

== General and cited references ==
* {{Cite book |last=Stull |first=Roland |date=2017 |title=Practical Meteorology: An Algebra-based Survey of Atmospheric Science |url=https://www.eoas.ubc.ca/books/Practical_Meteorology/ |publisher=University of British Columbia |isbn=978-0-88865-283-6}}
* {{Cite book |last=Whiteman |first=C. David |year=2000 |title=Mountain Meteorology: Fundamentals and Applications |publisher=Oxford University Press |isbn=0-19-513271-8}}

==External links==
* [http://www.euratlas.net/geography/europe/mountains/index.html Map of the Orography of Europe] from [[Euratlas.com]]

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[[Category:Geomorphology]]