Editing Yan'an (section)

==Geography==
[[File:1964-12 1964年 延安.jpg|thumb|left|150px|Yan'an in 1964]]
Yan'an is located in [[northern Shaanxi]] on the [[Loess Plateau]], with a latitude spanning from 35°21′ to 37°31′ N, and a longitude spanning from 107°41′ to 110°31′ E.<ref name=":11" /><ref name=":5">{{Cite web|date=2016-07-15|title=|script-title=zh:延安市概况地图|trans-title=Yan'an Overview|url=http://www.xzqh.org/html/show/sn/20381.html|url-status=live|archive-url=https://web.archive.org/web/20200813173550/http://xzqh.org/html/show/sn/20381.html|archive-date=2020-08-13|access-date=2021-05-14|publisher=XZQH.org|language=zh}}</ref> The city is bordered by [[Yulin, Shaanxi|Yulin]] to the north, [[Xianyang]], [[Tongchuan]], and [[Weinan]] in the [[Guanzhong]] region to the south, [[Linfen]] and [[Lüliang]] of [[Shanxi]] to the east across the middle reaches of the [[Yellow River]], and [[Qingyang, Gansu|Qingyang]] of [[Gansu]] to the west across the Ziwu Ridge ({{Lang-zh|c=子午岭}}).<ref name=":11" /><ref name=":5" /> The city's elevation is hilly, and is higher in the northwest, and lower in the southeast, ranging from {{convert|388.8|to|1809.8|m|ft}} above sea level in elevation.<ref name=":11" /><ref name=":5" /> The average elevation of Yan'an is approximately {{convert|1200|m|-1|abbr=on}},<ref name=":11" /> and Yan'an's [[urban core]] has an elevation of about {{convert|960|m|ft}} above sea level.<ref name=":5" /> In addition to the Yellow River flowing through Yan'an, the city's major rivers include the [[Yan River]] and the [[Luo River (Shaanxi)|Luo River]].<ref name=":5" />

=== Climate ===
Yan'an has a [[humid continental climate]] ([[Köppen climate classification]] ''Dwa'') that borders on a [[Semi-arid climate#Cold semi-arid climates|steppe climate]] (Köppen ''BSk''), with cold, dry, and moderately long winters, and hot, somewhat humid summers. Spring and autumn are short transition seasons in between. The monthly 24-hour average temperature ranges from {{convert|-5.5|°C|1}} in January to {{convert|23.1|°C|1}} in July, and the annual mean is {{convert|9.90|°C|1}}. The area receives {{convert|511|mm|in|1|sp=us}} of precipitation, 47% of which falls in July and August. Yan'an averages around 300 days of sunshine per year.

{{Weather box|width=auto
|metric first=y
|single line=y 
|collapsed = Y
|location = Yan'an, elevation {{convert|959|m|ft|abbr=on}}, (1991–2020 normals, extremes 1971–2000)
|Jan high C = 	2.3
|Feb high C = 	7.3
|Mar high C = 	13.3
|Apr high C = 	21.1
|May high C = 	25.8
|Jun high C = 	29.7
|Jul high C = 	30.5
|Aug high C = 	28.4
|Sep high C = 	23.7
|Oct high C = 	18.1
|Nov high C = 	11.1
|Dec high C = 	4.3
|Jan mean C = 	-4.9
|Feb mean C = 	-0.2
|Mar mean C = 	5.8
|Apr mean C = 	13.1
|May mean C = 	18.2
|Jun mean C = 	22.3
|Jul mean C = 	24.0
|Aug mean C = 	22.2
|Sep mean C = 	17.0
|Oct mean C = 	10.5
|Nov mean C = 	3.4
|Dec mean C = 	-2.9
|Jan low C = 	-10.3
|Feb low C = 	-5.8
|Mar low C = 	-0.1
|Apr low C = 	6.3
|May low C = 	11.3
|Jun low C = 	15.7
|Jul low C = 	18.8
|Aug low C = 	17.5
|Sep low C = 	12.3
|Oct low C = 	5.2
|Nov low C = 	-1.8
|Dec low C = 	-7.8
|Jan record high C = 16.6 |Jan record low C = -21.4
|Feb record high C = 23.8 |Feb record low C = -19.8
|Mar record high C = 27.6 |Mar record low C = -15.4
|Apr record high C = 34.4 |Apr record low C = -6.3
|May record high C = 36.5 |May record low C = -0.1
|Jun record high C = 37.5 |Jun record low C = 5.5
|Jul record high C = 38.3 |Jul record low C = 10.1
|Aug record high C = 36.9 |Aug record low C = 8.7
|Sep record high C = 37.5 |Sep record low C = 0.6
|Oct record high C = 29.7 |Oct record low C = -8.1
|Nov record high C = 25.5 |Nov record low C = -17.0
|Dec record high C = 18.0 |Dec record low C = -23.0
|year high C =  |year low C = 
|year high F =  |year low F =
|precipitation colour = green
|Jan precipitation mm = 	3.2
|Feb precipitation mm = 	5.3
|Mar precipitation mm = 	14.6
|Apr precipitation mm = 	25.6
|May precipitation mm = 	41.0
|Jun precipitation mm = 	64.1
|Jul precipitation mm = 	100.6
|Aug precipitation mm = 	110.0
|Sep precipitation mm = 	69.1
|Oct precipitation mm = 	38.4
|Nov precipitation mm = 	14.7
|Dec precipitation mm = 	2.4
|unit precipitation days = 0.1 mm	
|Jan precipitation days = 	2.4
|Feb precipitation days = 	3.0
|Mar precipitation days = 	4.6
|Apr precipitation days = 	5.9
|May precipitation days = 	7.8
|Jun precipitation days = 	9.0
|Jul precipitation days = 	12.0
|Aug precipitation days = 	11.1
|Sep precipitation days = 	9.8
|Oct precipitation days = 	8.1
|Nov precipitation days = 	3.9
|Dec precipitation days = 	2.0
|year precipitation days = 	
|Jan humidity = 	54
|Feb humidity = 	51
|Mar humidity = 	49
|Apr humidity = 	44
|May humidity = 	49
|Jun humidity = 	56
|Jul humidity = 	67
|Aug humidity = 	72
|Sep humidity = 	72
|Oct humidity = 	68
|Nov humidity = 	60
|Dec humidity = 	54
|Jan sun = 	196.5
|Feb sun = 	188.2
|Mar sun = 	218.8
|Apr sun = 	242.5
|May sun = 	262.6
|Jun sun = 	251.6
|Jul sun = 	231.0
|Aug sun = 	213.7
|Sep sun = 	176.0
|Oct sun = 	190.8
|Nov sun = 	191.3
|Dec sun = 	192.3
|year sun = 	
| Jan percentsun = 	63
| Feb percentsun = 	61
| Mar percentsun = 	59
| Apr percentsun = 	61
| May percentsun = 	60
| Jun percentsun = 	57
| Jul percentsun = 	52
| Aug percentsun = 	52
| Sep percentsun = 	48
| Oct percentsun = 	55
| Nov percentsun = 	63
| Dec percentsun = 	64
| year percentsun =	
|Jan snow days = 	4.3
|Feb snow days = 	4.0
|Mar snow days = 	2.9
|Apr snow days = 	0.5
|May snow days = 	0
|Jun snow days = 	0
|Jul snow days = 	0
|Aug snow days = 	0
|Sep snow days = 	0
|Oct snow days = 	0.3
|Nov snow days = 	2.4
|Dec snow days = 	3.6
|year snow days = 	
|source 1 = [[China Meteorological Administration]]<ref name="cma graphical">{{cite web |url=http://data.cma.cn/data/weatherBk.html |script-title=zh:中国气象数据网 – WeatherBk Data |publisher=[[China Meteorological Administration]] |language = zh-hans |access-date=24 September 2023}}</ref><ref>
{{cite web|url=https://experience.arcgis.com/template/e724038fda394e9d9b7921f10fd1aa55/page/%E7%BA%AF%E8%A1%A8%E6%A0%BC%E7%BB%9F%E8%AE%A1-(%E5%AF%B9%E6%AF%948110%E5%8F%98%E5%8C%96)/?org=UQmaps |script-title=zh:中国气象数据网|publisher=[[China Meteorological Administration]] |language = zh-hans | access-date =24 September 2023 |title=Experience Template }}</ref>
|source 2 = Weather China<ref name=WCN>{{cite web|script-title=zh:延安城市介绍以及气候背景分析|url=http://www.weather.com.cn/cityintro/101170401.shtml? |website=Weather China|publisher=中国气象局公共气象服务中心|access-date=July 27, 2015|language=zh}}</ref>
}}

=== Pollution ===
Yan'an experiences moderate to severe air pollution year‐round. Its basin‐like terrain combined with frequent winter temperature inversions traps locally emitted pollutants, while heavy reliance on [[coal]] for industry and residential heating, growing vehicle use, and seasonal [[Dust storm|dust storms]] from surrounding arid regions together maintain high concentrations of [[particulate matter]] (PM<sub>2.5</sub> and PM<sub>10</sub>) and gaseous contaminants such as [[sulfur dioxide]] (SO<sub>2</sub>) and [[NOx|NO''x'']] gases.<ref name=":9">{{Cite journal |last1=Ma |first1=Shuai |last2=He |first2=Jinrong |last3=He |first3=Jinwei |last4=Feng |first4=Qiang |last5=Bi |first5=Yingzhou |date=2024-12-01 |title=Forecasting air quality Index in yan'an using temporal encoded Informer |url=https://linkinghub.elsevier.com/retrieve/pii/S0957417424017354 |journal=Expert Systems with Applications |volume=255 |pages=124868 |doi=10.1016/j.eswa.2024.124868 |issn=0957-4174|url-access=subscription }}</ref> Elevated PM<sub>2.5</sub> levels are linked to respiratory and cardiovascular diseases, while acid deposition from SO<sub>2</sub> and NO''x'' damages soils and vegetation across the fragile loess landscape.<ref>{{Cite journal |last1=Wang |first1=Di |last2=Zhu |first2=Shilei |last3=Wang |first3=Lijing |last4=Zhen |first4=Qing |last5=Han |first5=Fengpeng |last6=Zhang |first6=Xingchang |date=2020-02-21 |title=Distribution, Origins and Hazardous Effects of Polycyclic Aromatic Hydrocarbons in Topsoil Surrounding Oil Fields: A Case Study on the Loess Plateau, China |journal=International Journal of Environmental Research and Public Health |language=en |volume=17 |issue=4 |pages=1390 |doi=10.3390/ijerph17041390 |issn=1660-4601 |pmc=7068613 |pmid=32098176 |doi-access=free}}</ref>

Yan'an sits atop the highly erodible Loess Plateau, where thick wind‐deposited silt forms uneven terrain that impedes horizontal dispersion of air pollutants.<ref>{{Cite journal |last1=Xiao |first1=Yi |last2=Wang |first2=Rui |last3=Wang |first3=Fan |last4=Huang |first4=Huan |last5=Wang |first5=Jue |date=2022-03-01 |title=Investigation on spatial and temporal variation of coupling coordination between socioeconomic and ecological environment: A case study of the Loess Plateau, China |journal=Ecological Indicators |volume=136 |pages=108667 |bibcode=2022EcInd.13608667X |doi=10.1016/j.ecolind.2022.108667 |issn=1470-160X |doi-access=free}}</ref> On the eastern edge of the plateau, a persistent “warm cover” of anomalously warm air and downdrafts suppresses vertical mixing, creating a convergence line that carries and concentrates emissions along the slopes—a phenomenon that amplifies pollution levels by 50–150% compared to flatter regions.<ref name=":10">{{Cite journal |last1=Meng |first1=Kai |last2=Xu |first2=Xiangde |last3=Xu |first3=Xiaobin |last4=Wang |first4=Haoliang |last5=Liu |first5=Xiaohui |last6=Jiao |first6=Yayin |date=2019-11-16 |title=The Causes of "Vulnerable Regions" to Air Pollution in Winter in the Beijing-Tianjin-Hebei Region: A Topographic–Meteorological Impact Model Based on Adaptive Emission Constraint Technique |journal=Atmosphere |language=en |volume=10 |issue=11 |pages=719 |bibcode=2019Atmos..10..719M |doi=10.3390/atmos10110719 |issn=2073-4433 |doi-access=free}}</ref> During winter months, strong temperature inversions—layers of warmer air aloft capping colder surface air—further inhibit the vertical dilution of pollutants, leading to seasonal peaks in PM<sub>2.5</sub> concentrations and prolonged haze events.<ref name=":10" />

==== Sources of pollution ====
[[Coal mining]], coal‐fired [[Electricity generation|power generation]] and [[cement]] production dominate Yan'an's industrial sector, collectively releasing large volumes of SO<sub>2</sub>, NO''x'' gases, and coarse (PM<sub>10</sub>) and fine (PM<sub>2.5</sub>) particulate matter. Inefficient combustion and fugitive dust from these facilities are key contributors to the city's annual pollution burden.<ref name=":9" />

In winter, over 80% of households in northern China, which includes Yan'an and its surroundings, rely on coal combustion for space heating. Traditional stoves and boilers emit high levels of [[black carbon]] and PM<sub>2.5</sub>, driving sharp increases in airborne particulates during colder months.<ref name=":9" />

Road vehicles in Yan'an contribute significant quantities of nitrogen oxides, volatile organic compounds and fine particulates. Regional tracking studies identify [[Yulin, Shaanxi|Yulin]] and Yan’an as important sources for wintertime NO''x'' and PM transport within the [[Fen River|Fen]]‐[[Wei River|Wei]] River Valley, indicating that urban traffic emissions exacerbate local air quality problems.<ref>{{Cite journal |last1=Liu |first1=Qiangjun |last2=Liang |first2=Suping |last3=Xu |first3=Junlin |date=2022-10-19 |title=Characteristics and Sources of Air Pollution in Southern Shanxi Province |journal=Sustainability |language=en |volume=14 |issue=20 |pages=13511 |bibcode=2022Sust...1413511L |doi=10.3390/su142013511 |issn=2071-1050 |doi-access=free}}</ref>

Seasonal dust storms originating in the [[Mu Us Desert]] and adjacent arid zones inject pulses of PM<sub>10</sub> into Yan'an's atmosphere. Natural dust events can elevate particulate concentrations several‐fold within hours, compounding anthropogenic pollution and sustaining prolonged haze episodes.<ref>{{Cite journal |last1=Cheng |first1=Bowen |last2=Ma |first2=Yuxia |last3=Qin |first3=Pengpeng |last4=Wang |first4=Wanci |last5=Zhao |first5=Yuhan |last6=Liu |first6=Zongrui |last7=Zhang |first7=Yifan |last8=Wei |first8=Linbo |date=2024-06-26 |title=Characterization of air pollution and associated health risks in Gansu Province, China from 2015 to 2022 |journal=Scientific Reports |language=en |volume=14 |issue=1 |pages=14751 |bibcode=2024NatSR..1414751C |doi=10.1038/s41598-024-65584-2 |issn=2045-2322 |pmc=11208435 |pmid=38926518}}</ref>