Editing Yellowknife (section)

== Geography ==
[[File:Old Town and N'Dilo.JPG|thumb|left|Yellowknife was scoured down to rock during the [[last glacial period]], making the landscape very rocky, and slightly rolling, with many small lakes.]]
Yellowknife is on the [[Canadian Shield]], which was scoured down to rock during the [[last glacial period|last ice age]].<ref name="ulaval" /> The surrounding landscape is very rocky and slightly rolling, with many small lakes in addition to the larger Great Slave Lake.<ref>{{cite web|url=http://scaa.usask.ca/gallery/northern/content?pg=ex03-1|title=The Northern Eco-System|first=Curt |last=McManus|publisher=University of Saskatchewan|access-date=15 April 2008|df=dmy-all}}</ref> Trees such as spruce and [[birch]] are abundant in the area, as are smaller bushes, but there are also many areas of relatively bare rock with [[lichen]].<ref>{{cite web|url=http://scaa.usask.ca/gallery/northern/content?pg=ex11-1|title=The Plants and Animals of Northern Canada|publisher=University of Saskatchewan|access-date=15 April 2008|df=dmy-all}}</ref> Yellowknife's high latitude causes a large variation between day and night. Daylight hours range from five hours of daylight in December to 20&nbsp;hours in June. [[Twilight#Civil twilight|Civil Twilight]] lasts all night from late May to mid-July.<ref>{{cite web|url=http://www.timeanddate.com/sun/canada/yellowknife|title=Sunrise and sunset for Yellowknife|publisher=Time and Date.com|access-date=18 January 2016}}</ref>

=== Climate ===
Yellowknife has a [[subarctic climate]] ([[Köppen climate classification|Köppen]]: ''Dfc'', [[Trewartha climate classification|Trewartha]] ''Ecld''). Although winter is predominantly polar, rapid [[heat wave]]s emerge at the summit of summer due to the immense path south.<ref>{{cite web|title=The High Subarctic Forest-Tundra of Northwestern Canada: Position, Width, and Vegetation Gradients in Relation to Climate|publisher=University of Calgary|first1=K.P.|last1=Timoney|first2=G.H.|last2=la Roi|first3=S.C.|last3=Zoltai|first4=A.L.|last4=Robinson|url=http://pubs.aina.ucalgary.ca/arctic/Arctic45-1-1.pdf|year=1991|access-date=2 March 2008|df=dmy-all|archive-date=3 October 2018|archive-url=https://web.archive.org/web/20181003195826/http://pubs.aina.ucalgary.ca/arctic/Arctic45-1-1.pdf|url-status=dead}}</ref> The city averages less than {{cvt|300|mm}} of precipitation annually, as it lies in the [[rain shadow]] of mountain ranges to the west.<ref name="YZFccn"/> Due to its location on Great Slave Lake, Yellowknife has a frost-free [[growing season]] that averages slightly over 100&nbsp;days.<ref name="ulaval">{{cite web|url=http://www.cen.ulaval.ca/paleo/publications/Articles/Pienitz.1997b.pdf|archive-url=https://web.archive.org/web/20080409145807/http://www.cen.ulaval.ca/paleo/publications/Articles/Pienitz.1997b.pdf |archive-date=9 April 2008|title=Physical and chemical limnology|publisher=University of Laval|access-date=2 March 2008|df=dmy-all}}</ref> In an occasional year, the first fall frost does not come until October.<ref>{{Cite web|url=https://climate.weather.gc.ca/climate_data/daily_data_e.html?hlyRange=1953-01-01%7C2013-01-17&dlyRange=1942-07-01%7C2013-01-16&mlyRange=1942-01-01%7C2007-11-01&StationID=1706&Prov=NT&urlExtension=_e.html&searchType=stnName&optLimit=specDate&StartYear=1840&EndYear=2019&selRowPerPage=25&Line=0&searchMethod=contains&Month=9&Day=25&txtStationName=yellowknife&timeframe=2&Year=2012|title=Daily Data Report for September 2012 - Climate - Environment and Climate Change Canada|website=climate.weather.gc.ca}}</ref> Most of the limited precipitation falls between June and October, with April being the driest month of the year and August having the most rainfall. Snow that falls in winter accumulates on the ground until the spring thaw.
[[File:Ice Fog in Yellowknife.jpg|thumb|left|Heavy [[ice fog]] can develop on the coldest winter mornings]]
Yellowknife experiences very cold winters and mild to warm summers. The average temperature in January is around {{cvt|-26|C}} and {{cvt|17|C}} in July.<ref name="YZFccn"/> According to [[Environment and Climate Change Canada]], Yellowknife has the sunniest summer in the country, averaging 1,034&nbsp;hours from June to August.<ref name=weatherwinners>{{cite web|url=http://www.climate.weatheroffice.gc.ca/winners/categorydata_e.html?SelectedCategory=43&submit=Submit |archive-url=https://archive.today/20121216035648/http://www.climate.weatheroffice.gc.ca/winners/categorydata_e.html?SelectedCategory=43&submit=Submit |url-status=dead |archive-date=16 December 2012 |title=Sunniest Summer |work=Weather Winners |publisher=Environment Canada |access-date=15 May 2013 }}</ref> The lowest temperature ever recorded in Yellowknife was {{cvt|-51.2|C}} on 31 January 1947, and the highest was {{cvt|32.6|C}} on 2 August 2021.<ref name="YZFccn"/> Yellowknife averages 2256.5&nbsp;hours of bright sunshine per year or 43.5% of possible daylight hours, ranging from a low of 15.4% in December to a high of 63.0% in June.<ref name="YZFccn"/> Due to its warm summer temperatures, Yellowknife is well below the Arctic [[tree line]] in stark contrast to areas farther east in Canada on similar parallels.

In 2014, Environment Canada ranked Yellowknife as having the coldest winter and longest snow cover season, along with the sunniest spring and summer, of any city in Canada.<ref>{{cite web|url=http://www.cbc.ca/news/canada/north/yellowknife-the-coldest-sunniest-city-in-canada-1.2499278|title=Yellowknife the coldest, sunniest city in Canada|publisher=CBC News|archive-url=https://web.archive.org/web/20230822225358/https://www.cbc.ca/news/canada/north/yellowknife-the-coldest-sunniest-city-in-canada-1.2499278
|archive-date=2023-08-22}}</ref>
<div style="width:75%">{{Yellowknife weatherbox}}
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=== Arsenic contamination ===
The area has elevated levels of arsenic due to the region's geology and past mining operations. The bedrock contains arsenopyrite, a naturally occurring mineral that contains arsenic, iron, and sulfur. Gold mining in the 20th century released large amounts of arsenic into the environment. The roasting process used to extract gold from arsenopyrite ores created arsenic trioxide as a byproduct, which was often released directly into the environment. 
The Giant Mine, which operated from 1948 to 2004, left behind 237,000 tonnes of arsenic trioxide waste on site. The mine is located 4 km north of Yellowknife's city limits. The Government of the Northwest Territories is working with researchers to monitor and study arsenic levels in the area. The Giant Mine Remediation Project is a billion-dollar cleanup effort that will take about 10 years to complete. There are several ongoing programs to monitor residents for elevated levels of arsenic.<ref>https://www.cbc.ca/news/canada/north/canada-150-betsina-family-nwt-1.4180681</ref><ref name="auto">{{Cite web|url=https://www.hss.gov.nt.ca/en/newsroom/arsenic-lake-water-around-yellowknife|title=Arsenic in Lake Water Around Yellowknife|first=Health and Social|last=Services|website=www.hss.gov.nt.ca}}</ref>