Editing Snow (section)

==Accumulation==
[[File:Earth-satellite-seasons.gif|thumb|upright=1.2|An animation of seasonal snow changes, based on satellite imagery]]
Snow accumulates from a series of snow events, punctuated by freezing and thawing, over areas that are cold enough to retain snow seasonally or perennially. Major snow-prone areas include the [[Arctic]] and [[Antarctic]], the Northern Hemisphere, and alpine regions. The liquid equivalent of snowfall may be evaluated using a [[snow gauge]]<ref>{{cite web|url=http://www.on.ec.gc.ca/skywatchers/ontario/wx_office_tour/compound/snow_e.html |title=Nipher Snow Gauge |publisher=On.ec.gc.ca |date=August 27, 2007 |access-date=August 16, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110928121043/http://www.on.ec.gc.ca/skywatchers/ontario/wx_office_tour/compound/snow_e.html |archive-date=September 28, 2011 }}</ref> or with a standard [[rain gauge]], adjusted for winter by removal of a funnel and inner cylinder.<ref>{{cite news|author=National Weather Service Office, Northern Indiana|author-link=National Weather Service|publisher=[[National Weather Service]] Central Region Headquarters|url=http://www.crh.noaa.gov/iwx/program_areas/coop/8inch.php|title=8 Inch Non-Recording Standard Rain Gage|access-date=January 2, 2009|date=April 13, 2009|url-status=live|archive-url=https://web.archive.org/web/20081225234123/http://www.crh.noaa.gov/iwx/program_areas/coop/8inch.php|archive-date=December 25, 2008|df=mdy-all}}</ref> Both types of gauges melt the accumulated snow and report the amount of water collected.<ref>[[National Weather Service]] Office [[Binghamton, New York]] (2009). [http://www.erh.noaa.gov/bgm/spotters_skywarn/precip4.shtml Raingauge Information.] {{webarchive|url=https://web.archive.org/web/20081013090524/http://www.erh.noaa.gov/bgm/spotters_skywarn/precip4.shtml |date=October 13, 2008 }} Retrieved on January 2, 2009.</ref> At some [[automatic weather station]]s an ultrasonic snow depth sensor may be used to augment the precipitation gauge.<ref>{{cite web|url=http://www.on.ec.gc.ca/skywatchers/ontario/wx_office_tour/compound/geonor_e.html |title=All-Weather Precipitation Gauge |publisher=On.ec.gc.ca |date=August 27, 2007 |access-date=August 16, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110928121114/http://www.on.ec.gc.ca/skywatchers/ontario/wx_office_tour/compound/geonor_e.html |archive-date=September 28, 2011 }}</ref>

===Event===
[[File:Winter Storm Jonas 2016 NYC Pershing Square.jpg|thumb|[[New York City]] during a [[January 2016 United States blizzard|2016 blizzard]], which produced strong winds and record-breaking snowfall.]]

[[Snow flurry]], [[Shower (precipitation)|snow shower]], [[snow storm]] and [[blizzard]] describe snow events of progressively greater duration and intensity.<ref>{{cite web|url=http://amsglossary.allenpress.com/glossary/search?id=snow-flurry1|author=Glossary of Meteorology|year=2009|access-date=June 28, 2009|publisher=[[American Meteorological Society]]|title=Snow flurry|url-status=dead|archive-url=https://web.archive.org/web/20071127144615/http://amsglossary.allenpress.com/glossary/search?id=snow-flurry1|archive-date=November 27, 2007|df=mdy-all}}</ref> A [[blizzard]] is a weather condition involving snow and has varying definitions in different parts of the world. In the [[United States]], a blizzard occurs when two conditions are met for a period of three hours or more: a sustained wind or frequent gusts to {{convert|sp=us|35|mph|m/s}}, and sufficient snow in the air to reduce visibility to less than {{convert|sp=us|0.4|km|mi}}.<ref>{{cite web |title = National Weather Service Glossary |url = http://www.nws.noaa.gov/glossary/index.php?letter=b |publisher = [[National Weather Service]] |year = 2009 |access-date = July 12, 2009 |url-status=live |archive-url = https://web.archive.org/web/20090509183315/http://www.nws.noaa.gov/glossary/index.php?letter=b |archive-date = May 9, 2009 |df = mdy-all }}</ref> In [[Canada]] and the [[United Kingdom]], the criteria are similar.<ref>{{cite web|title=Blizzards |url=http://www.mb.ec.gc.ca/air/wintersevere/blizzards.en.html |work=Winter Severe Weather |publisher=Environment Canada |date=September 4, 2002 |access-date=July 12, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090211120800/http://www.mb.ec.gc.ca/air/wintersevere/blizzards.en.html |archive-date=February 11, 2009 }}</ref><ref>{{cite web|title= Key to flash warning criteria |url= http://www.metoffice.gov.uk/weather/uk/guide/key_warnings.html |archive-url= https://web.archive.org/web/20101229172227/http://www.metoffice.gov.uk/weather/uk/guide/key_warnings.html |archive-date= December 29, 2010 |author= Met Office|author-link= Met Office |date=November 19, 2008|access-date= July 12, 2009}}</ref> While heavy snowfall often occurs during blizzard conditions, falling snow is not a requirement, as [[blowing snow]] can create a [[ground blizzard]].<ref>{{cite web |title = Blizzards |url = http://www.wrh.noaa.gov/fgz/science/blizzard.php?wfo=fgz |author = [[National Weather Service]] Forecast Office, [[Flagstaff, Arizona]] |publisher = [[National Weather Service]] Western Region Headquarters |access-date = July 12, 2009 |date = May 24, 2007 |url-status=live |archive-url = https://web.archive.org/web/20090115090647/http://www.wrh.noaa.gov/fgz/science/blizzard.php?wfo=fgz |archive-date = January 15, 2009 |df = mdy-all }}</ref>

Snowstorm intensity may be categorized by visibility and depth of accumulation.<ref>{{cite web|url=http://www.nws.noaa.gov/om/brochures/wntrstm.htm |title=Winter Storms...the Deceptive Killers |publisher=United States [[Department of Commerce]] |date=November 1991 |access-date=June 28, 2009 |author=National Oceanic and Atmospheric Administration |author-link=National Oceanic and Atmospheric Administration |url-status=dead |archive-url=https://web.archive.org/web/20090608185155/http://www.nws.noaa.gov/om/brochures/wntrstm.htm |archive-date=June 8, 2009 }}</ref> Snowfall's intensity is determined by [[visibility]], as follows:<ref>{{cite web|title=Snow|author=Glossary of Meteorology|url=http://amsglossary.allenpress.com/glossary/search?id=snow1|publisher=[[American Meteorological Society]]|year=2009|access-date=June 28, 2009|url-status=dead|archive-url=https://web.archive.org/web/20090220090504/http://amsglossary.allenpress.com/glossary/search?id=snow1|archive-date=February 20, 2009|df=mdy-all}}</ref>
* ''Light'': visibility greater than {{convert|sp=us|1|km|mi|sigfig=1}}
* ''Moderate'': visibility restrictions between {{convert|sp=us|0.5|and|1|km|mi|sigfig=1}}
* ''Heavy'': visibility is less than {{convert|sp=us|0.5|km|mi|sigfig=1}}
[[Snowsquall]]s may deposit snow in bands that extend from bodies of water as lake-event weather or result from the passage of an upper-level front.<ref name="popsci/nasa-snowstorm">{{cite news |date=3 February 2022 |title=NASA's storm-chasing planes fly through blizzards to improve snowfall forecasts |work=[[Popular Science]] |url=https://www.popsci.com/science/nasa-planes-improve-snowstorm-forecasts/ |access-date=9 March 2023}}</ref><ref name="weather/bandedsnowfall">{{cite web |author1=NOAA |title=What causes bands of heavy snowfall? |url=https://www.weather.gov/fsd/news_bandedsnowfall_20151121 |access-date=9 March 2023 |website=weather.gov |publisher=US Department of Commerce |language=EN-US}}</ref><ref name="nbcmontana/snow-bands">{{cite web |last1=Coombs |first1=Mitchel |date=28 November 2022 |title=3D Weather: Science of snow bands |url=https://nbcmontana.com/news/local/3d-weather-science-of-snow-bands |access-date=9 March 2023 |website=[[KECI]] |language=en}}</ref>

The ''International Classification for Seasonal Snow on the Ground'' defines "height of new snow" as the depth of freshly fallen snow, in centimeters as measured with a ruler, that accumulated on a [[snowboard (meteorology)|snowboard]] during an observation period of 24 hours, or other observation interval. After the measurement, the snow is cleared from the board and the board is placed flush with the snow surface to provide an accurate measurement at the end of the next interval.<ref name = Classificationonground/> Melting, compacting, blowing and drifting contribute to the difficulty of measuring snowfall.<ref>{{cite web|url=http://www.crh.noaa.gov/iwx/program_areas/snow_spotters/SnowMeasurement.pdf|title=Snow Measurement Guidelines for National Weather Service Snow Spotters|author=National Weather Service Forecast Office Northern Indiana|author-link=National Weather Service|publisher=National Weather ServiceCentral Region Headquarters|date=October 2004|url-status=live|archive-url=https://web.archive.org/web/20100215064901/http://www.crh.noaa.gov/iwx/program_areas/snow_spotters/SnowMeasurement.pdf|archive-date=February 15, 2010|df=mdy-all}}</ref>

===Distribution===
[[File:Snow-covered fir trees.jpg|thumb|Snow-covered trees in [[Kuusamo]], [[Finland]]]]
Glaciers with their permanent snowpacks cover about 10% of the earth's surface, while seasonal snow covers about nine percent,<ref name = Snowenclyclopedia/> mostly in the Northern Hemisphere, where seasonal snow covers about {{convert|40|e6km2}}, according to a 1987 estimate.<ref>
{{cite journal
 |last1        = Chang
 |first1       = A.T.C.
 |last2       = Foster
 |first2      = J.L.
 |last3       = Hall
 |first3      = D.K.
 |title       = NIMBUS-7 SMMR derived global snow parameters
 |journal     = Annals of Glaciology
 |volume      = 9
 |date        = 1987
 |df          = mdy-all
|doi = 10.1017/S0260305500200736
 |pages = 39–44
 |doi-access= free
 }}</ref> A 2007 estimate of snow cover over the Northern Hemisphere suggested that, on average, snow cover ranges from a minimum extent of {{convert|2|e6km2}} each August to a maximum extent of {{convert|45|e6km2}} each January or nearly half of the land surface in that hemisphere.<ref>
{{Citation
 | last = Lemke
 | first = P.
 | display-authors = etal
 | editor-last = Solomon
 | editor-first = S.
 | display-editors = etal
 | contribution = Observations: Changes in snow, ice and frozen ground
 | title = Climate Change 2007: The Physical Science Basis
 | year = 2007
 | pages = 337–383
 | place = New York
 | publisher = Cambridge Univ. Press
 }}</ref><ref name=Déry>
{{Citation
 |last1        = Déry
 |first1       = S. J
 |last2       = Brown
 |first2      = R. D.
 |title       = Recent Northern Hemisphere snow cover extent trends and implications for the snow-albedo feedback
 |journal     = Geophysical Research Letters
 |volume      = 34
 |issue       = L22504
 |pages       = L22504
 |year        = 2007
 |doi         = 10.1029/2007GL031474
 |bibcode       = 2007GeoRL..3422504D
 |doi-access= free
 }}</ref> A study of Northern Hemisphere snow cover extent for the period 1972–2006 suggests a reduction of {{convert|0.5|e6km2}} over the 35-year period.<ref name = Déry/>

===Records===
The following are world records regarding snowfall and snowflakes:
* ''Highest seasonal total snowfall'' – The world record for the highest seasonal total snowfall was measured in the United States at [[Mt. Baker Ski Area]], outside of the city of [[Bellingham, Washington]] during the 1998–1999 season. Mount Baker received {{convert|2896|cm|ft|abbr=on}} of snow,<ref>{{cite web|url=https://www.usatoday.com/weather/news/1999/wsnorcrd.htm|title=NOAA: Mt. Baker snowfall record sticks|work=[[USA Today]]|date=August 3, 1999|access-date=June 30, 2009|url-status=live|archive-url=https://web.archive.org/web/20090424104329/http://www.usatoday.com/weather/news/1999/wsnorcrd.htm|archive-date=April 24, 2009|df=mdy-all}}</ref> thus surpassing the previous record holder, [[Mount Rainier]], Washington, which during the 1971–1972 season received {{convert|2850|cm|ft|abbr=on}} of snow.<ref>{{cite web|url=http://www.nps.gov/archive/mora/interp/faq.htm|archive-url=https://web.archive.org/web/20070221204740/http://www.nps.gov/archive/mora/interp/faq.htm|url-status=dead|archive-date=February 21, 2007|title=Frequently Asked Questions|author=Mount Rainier National Park|author-link=Mount Rainier National Park|publisher=[[National Park Service]]|date=April 14, 2006|access-date=June 30, 2009}}</ref>
* ''Highest seasonal average annual snowfall'' – The world record for the highest average annual snowfall is {{convert|1764|cm|ft|abbr=on}},<ref>{{cite web | url = http://www.data.jma.go.jp/obd/stats/etrn/view/nml_amd_ym.php?prec_no=31&block_no=1079&year=&month=&day=&view= | title = JMA | access-date = November 12, 2012 | publisher = JMA | language = ja | url-status=live | archive-url = https://web.archive.org/web/20130618204127/http://www.data.jma.go.jp/obd/stats/etrn/view/nml_amd_ym.php?prec_no=31&block_no=1079&year=&month=&day=&view= | archive-date = June 18, 2013 | df = mdy-all }}</ref> measured in [[Sukayu Onsen]], Japan for the period of 1981–2010.
* ''Largest snowflake'' – According to ''[[Guinness World Records]],'' the world's largest snowflake fell in January 1887 outside present-day [[Miles City, Montana|Miles City]], [[Montana]]. It measured {{convert|38|cm|in|abbr=on}} in diameter.<ref>{{cite news |url=https://www.nytimes.com/2007/03/20/science/20snow.html |title=Giant Snowflakes as Big as Frisbees? Could Be |newspaper=New York Times |author=William J. Broad |date=March 20, 2007 |access-date=July 12, 2009 |url-status=live |archive-url=https://web.archive.org/web/20111104033402/http://www.nytimes.com/2007/03/20/science/20snow.html |archive-date=November 4, 2011 |df=mdy-all }}</ref>

The cities (more than 100,000 inhabitants) with the highest annual snowfall are [[Aomori]] (792&nbsp;cm), [[Sapporo]] (485&nbsp;cm) and [[Toyama, Toyama|Toyama]] (363&nbsp;cm) in [[Japan]], followed by [[St. John's, Newfoundland and Labrador|St. John's]] (332&nbsp;cm) and [[Quebec City]] (315&nbsp;cm) in [[Canada]], and [[Syracuse, NY]] (325&nbsp;cm).<ref>{{cite web |title=Top 10 snowiest major cities around the world |url=https://www.accuweather.com/en/weather-news/top-10-snowiest-major-cities-around-the-world/375130 |website=Accuweather |access-date=4 March 2023}}</ref>