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用戶:Towerman/translation/雪

維基百科，自由的百科全書
天氣條目系列之一
天氣
溫帶及極地季節
熱帶季節
風暴
降水
主題（英語：Index of meteorology topics）
詞彙表
氣象主題
美國科羅拉多州森林中的雪
不同形狀的雪花

雪是降水形式的一種，是從雲中降落的水的結晶狀固體冰（常以雪花的形式存在）。因為雪是由小的冰顆粒物構成，所以是一種顆粒材料（英語：granular material）。它的結構開放，因此顯得柔軟。雪花有多種的形式和大小。球狀降雪是由於在降落過程中雪被融化後又重新凍結，此類降雪有冰雹、冰丸、米雪。

雪降落的過程被稱為下雪或降雪。降雪一般形成於被稱為溫帶氣旋的一種低氣壓系統周圍的空氣向上運動的區域中。雪可能會在那些伴隨着暖鋒的天氣系統裏向極地方向降落，降雪發生在這些系統的逗號頭型降水模式（在溫帶氣旋的西面和向極的區域附近的逗號形狀的雲和降水模式）中。在有相對較暖的水體存在的地方（比如從湖泊中蒸發的水汽），大湖效應降雪變得重要，一般發生在暖湖的下風向，在溫帶氣旋的背後的寒冷的氣旋氣流中。湖效應降雪在局部地區可能會非常大。雷打雪可能會發生在氣旋的逗號頭裏和湖效應降水帶里。在山區，上坡氣流在上升過程中在山坡的迎風（英語：Windward and leeward）面達到極限，如果這時空氣夠冷的話，有可能會有大雪發生。降雪量以及對應的雪水當量降水量是由多種雨量計測量得到的。

形成

火車被雪阻着
  • 大氣中的水蒸汽直接凝華或水滴直接凝固而成，就是雪。也可說是雲中的溫度過低，小水滴結成冰晶，落到地面仍然是雪花時，就是下雪了。冰融化時會吸熱，所以地面氣溫會比下雪時低。

條件

  1. 大氣中需含有較冷的冰晶核。
  2. 充分的水汽。
  3. 0℃（冰點）以下。如該冷空氣相當強烈，並帶着濕氣，1℃至10℃的氣溫同樣可以降雪。

能降雪的地方

氣候區屬中緯度至高緯度（即大約於南回歸線以南／北回歸線以北地區）的地方就會有降雪的機會，如果於低緯度地方中有些地勢高於海拔2000米的高山或高原也有同樣的機會。

海洋氣流也能間接影響該區下雪的機會率，如果在高緯度地區一帶有較多暖流支配，會減低該區下雪的機會（例如日本本州至九州一帶）。

雪花

主條目：雪花

雪花是在雲內由微小的冰晶互撞黏在一起後形成豐富多樣的形狀。沒有兩個雪花是完全相同的，但雪花仍然謹守着最初的冰晶基本的六角形對稱標準結構。透過顯微鏡可以看見雪花錯綜複雜的構造大多都是六角形的，而雪花的中心一定呈現出對稱的六角形，它之所以有這樣的形狀，是因為它要在平面上以最有效率的方式佈置，它是結晶學的研究對象之一。

天氣非常寒冷時，冰晶不易黏在一起，雪呈細粉狀的小雪珠。雪珠是雲中溫度低於攝氏零度的許多小雲滴在冰晶上互相碰撞凝結而成，仔細觀察雪珠的形狀，可以看出小雪珠是由許多細白的冰粒聚集而成的。當冷空氣逐漸向前推移，上升氣流減弱，雲中水氣直接在冰晶上凝結成較大的形態，此即我們所見到的雪花。如果溫度接近冰點，則會落下濕雪，形成較大的雪花，特別是無風的時候。大型的星形雪花直徑可達5到7公分。多數的雪花在落下地面的途中會融化成雨，只有當接近地面的空氣夠冷，才能讓雪花落到地面成雪。

紀錄

世界最高的季節降雪量有2,896 cm（1,140英寸），是於1998－1999降雪季節在美國華盛頓州貝靈厄姆附近的貝克山滑雪場處測得。[1]此前的記錄為2,850 cm（1,120英寸），是於1971－1972降雪季節在美國華盛頓州的瑞尼爾山測得。[2]

世界最高年平均降雪量有1,764 cm（694英寸），[3]是於1981-2010年間在日本青森縣的酸湯溫泉（英語：Sukayu Onsen）處測得。

北美最高的年降雪量為1,630 cm（641英寸），[4]是在美國華盛頓州的瑞尼爾山測得。

世界最深的雪深有1,182 cm（465英寸），是於1927年2月14日在日本伊吹山的高度為1,200米（3,900 ft）處的山坡上測得。[5]

北美最高的雪深為1,150 cm（451英寸），是於1911年3月在美國加州塔馬拉克（英語：Tamarack, California）2,100米（7,000 ft）高度處測得。[5]

世界上人口超過百萬的大城市中降雪最多的城市是日本的札幌市，年平均降雪為595 cm（234英寸）。

雪的融化

當有能量輸入的時候，積雪會由固態轉變為其他形態。使積雪融化的能量可能來自下列途徑：輻射（太陽發出的短波輻射或者長波熱輻射）、熱傳導（當氣溫高於0℃時），或者通過落入積雪的，溫度超過0℃的雨滴。積雪的融化速度，不僅取決於所輸入的能量的多少，也取決於當時的氣溫和濕度。具體說來，空氣越乾燥，積雪融化的速度越慢，因為此時雪更容易升華——即固體不經由液體，直接轉變為氣體的過程——而升華需要較多的能量，這使得周圍的積雪被冷卻，從而減緩了融化的速度。

通過「濕球溫度」和「露點溫度」，我們可以界定積雪融化過程的三個狀態。「濕球溫度」指的是從乾濕計的濕球溫度計上讀出的溫度，該溫度始終低於大氣溫度——即使大氣相對濕度為100%的時候也不例外。而「露點溫度」指的是，空氣中所含的氣態水達到飽和，從而凝結成液態水所需要的溫度。露點溫度又總是低於濕球溫度。

  • 當濕球溫度低於0℃的時候，積雪升華。這個過程十分緩慢，而此時積雪也保持乾燥。在相對濕度小於20%的時候，升華甚至可以在7℃的氣溫下進行。
  • 當濕球溫度高於0℃，而露點溫度低於0℃的時候，積雪熔解。這時，固態的雪既轉化為氣態，同時又轉化為液態。
  • 當露點溫度也高於0℃的時候，積雪會融解，也就是說，積雪只從固態轉變為液態。這時積雪融化的速度最快。

舉例來說，在相對濕度為50%的時候，當氣溫低於3.5℃時，積雪升華；當氣溫介於3.5－10℃之間時，積雪熔解；當氣溫高於10℃，則積雪融解。

雪對人類社會的影響

A snow blockade in southern Minnesota, US in 1881
Driving in a blinding snowstorm can be dangerous and risky.

Substantial snowfall can disrupt public infrastructure and services, slowing human activity even in regions that are accustomed to such weather. Air and ground transport may be greatly inhibited or shut down entirely. Populations living in snow-prone areas have developed various ways to travel across the snow, such as skis, snowshoes, and sleds pulled by horses, dogs, or other animals and later, snowmobiles. Basic utilities such as electricity, telephone lines, and gas supply can also fail. In addition, snow can make roads much harder to travel and vehicles attempting to use them can easily become stuck.[6] Snowfall can have a small negative effect on yearly yield from solar photovoltaic systems.[7]

The combined effects can lead to a "snow day" on which gatherings such as school or work are officially canceled. In areas that normally have very little or no snow, a snow day may occur when there is only light accumulation or even the threat of snowfall, since those areas are unprepared to handle any amount of snow. In some areas, such as some states in the United States, schools are given a yearly quota of snow days (or "calamity days"). Once the quota is exceeded, the snow days must be made up.[8][9][10] In other states, all snow days must be made up.[11] For example, schools may extend the remaining school days later into the afternoon, shorten spring break, or delay the start of summer vacation.

Accumulated snow is removed to make travel easier and safer, and to decrease the long-term impact of a heavy snowfall. This process utilizes shovels, snowplows and snow blowers and is often assisted by sprinkling salt or other chloride-based chemicals, which reduce the melting temperature of snow.[12] In some areas with abundant snowfall, such as Yamagata Prefecture, Japan, people harvest snow and store it surrounded by insulation in ice houses. This allows the snow to be used through the summer for refrigeration and air conditioning, which requires far less electricity than traditional cooling methods.[13]

Agriculture

Snowfall can be beneficial to agriculture by serving as a thermal insulator, conserving the heat of the Earth and protecting crops from subfreezing weather. Some agricultural areas depend on an accumulation of snow during winter that will melt gradually in spring, providing water for crop growth. If it melts into water and refreezes upon sensitive crops, such as oranges, the resulting ice will protect the fruit from exposure to lower temperatures.[14]

娛樂

牛津的學生們正在製造一個大雪球

有很多種冬季運動和娛樂方式都依賴於雪，比如滑雪[15]、單板滑雪[16]、雪地摩托[17]、踏雪健行、滾雪球，堆雪人、打雪仗等。Where snow is scarce but the temperature is low enough, snow cannons may be used to produce an adequate amount for such sports.[18] Children and adults can play on a sled or ride in a sleigh. Although a person's footsteps remain a visible lifeline within a snow-covered landscape, snow cover is considered a general danger to hiking since the snow obscures landmarks and makes the landscape itself appear uniform.[19]

Making a snow angel

One of the recognizable recreational uses of snow is in building snowmen. A snowman is created by making a man shaped figure out of snow – often using a large, shaped snowball for the body and a smaller snowball for the head which is often decorated with simple household items – traditionally including a carrot for a nose, and coal for eyes, nose and mouth; occasionally including old clothes such as a top hat or scarf.

Snow can be used to make snow cones, also known as snowballs, which are usually eaten in the summer months[來源請求].[20] Flat areas of snow can be used to make snow angels, a popular pastime for children.

雪還可以被用於雪雕，是在嚴寒國家盛行的戶外藝術之一。雪雕主要就是將雪當做塑形的材料，把它捏成固定的形狀，再組合起來並修整細節，跟沙雕的原理頗為相近。很多寒冷地區城市都會在冬季舉辦冰雪節（英語：List of ice and snow sculpture events），雪雕和冰雕都是冰雪節的重要組成部分。比如在中國東北地區是雪雕藝術最發達的地區，特別是哈爾濱市太陽島風景區每年都會舉辦規模盛大的雪雕藝術博覽會。

Snow can be used to alter the format of outdoor games such as Capture the flag,[21] or for snowball fights. The world's biggest snowcastle, the SnowCastle of Kemi, is built in Kemi, Finland every winter.[22] Since 1928 Michigan Technological University in Houghton, Michigan has held an annual Winter Carnival in mid-February, during which a large Snow Sculpture Contest takes place between various clubs, fraternities, and organizations in the community and the university. Each year there is a central theme, and prizes are awarded based on creativity.[23] Snowball softball tournaments are held in snowy areas, usually using a bright orange softball for visibility, and burlap sacks filled with snow for the bases.[24]

雪文化

雪害

日本的 Tsuzumi，一種不常見的雪晶，因形狀像沙漏鼓而得名
  • 造成凍傷
  • 雪融後造成水災
  • 阻塞交通
  • 路面濕滑，容易滑倒
  • 積雪過厚導致建築屋頂坍塌

地外行星的雪

已知在火星的高緯度地區有很少量的雪。[25]在土星的衛星土衛六上，有可能存在一種由碳氫化合物構成的「雪」。[26]

雖然在金星上幾乎沒有水，但也存在一種與雪非常類似的自然現象。麥哲倫號探測器在金星最高的山峰上拍到了高反射的物質，它和地球上的雪非常類似。這種物質的形成過程可能與雪的形成類似，但要求的溫度很高。因為其高揮發性，它不能在地表凝結，因此成為氣體上升到較冷的高地，然後在那裏凝結並降落。這種物質的成分還不能確定，有可能是元素碲或硫化鉛（方鉛礦）。[27]

參看

參考文獻

  1. ^ USA Today. NOAA: Mt. Baker snowfall record sticks. 1999-08-03 [2009-06-30]. 
  2. ^ Mount Rainier National Park. Frequently Asked Questions. National Park Service. 2006-04-14 [2009-06-30]. 
  3. ^ JMA. JMA. [November 12, 2012]. 
  4. ^ Annual Snowfall Totals at Paradise, 1920 to 2011 (PDF). National Park Service. 
  5. ^ 5.0 5.1 Christopher C. Burt. Record Snow Depth (for an official site) Measured in Japan. Weather Underground. 
  6. ^ Laura Cheshire. Have Snow Shovel, Will Travel. National Snow and Ice Data Center. 1997 [2009-07-08]. 
  7. ^ Rob Andrews and Joshua M. Pearce, 「Prediction of Energy Effects on Photovoltaic Systems due to Snowfall Events」 in: 2012 38th IEEE Photovoltaic Specialists Conference (PVSC). Presented at the 2012 38th IEEE Photovoltaic Specialists Conference (PVSC), pp. 003386 –003391. Available: DOI open access
  8. ^ Dave Larsen. School districts are using up calamity days. Dayton Daily News (Dayton, Ohio: Cox Enterprises). 2009-01-27 [2009-02-05]. Ohio school districts can use five calamity days before they must start adding extra days to the school calendar.  [失效連結]
  9. ^ Donna Willis. Districts Consider Calamity Options. WCMH-TV (Columbus, Ohio: Media General). 2009-01-30 [2009-02-05]. 
  10. ^ Joleen Ferris. Decision for city schools to stay open prompts calls from irate parents. WKTV (Utica, New York: Smith Media). 2009-01-28 [2009-02-05]. 
  11. ^ Christine Wolff, Tanya Albert. Snow may stretch out school year. The Cincinnati Enquirer (Cincinnati, Ohio: Gannett Company). 1999-03-09 [2009-02-05]. 
  12. ^ David A. Kuemmel. Managing roadway snow and ice control operations. Transportation Research Board. 1994: 10 [2009-07-08]. ISBN 978-0-309-05666-3. 
  13. ^ United Nations Environment Programme. Using Snow For Cool, Innovative Solutions. Insight. Winter 1996 [2009-07-08]. 
  14. ^ M. Baldwin. How Cold Can Water Get?. Argonne National Laboratory. 2002-09-08 [2009-04-16]. 
  15. ^ Christopher Clarey. NAGANO '98; Building a Better Snowman Through Science. New York Times. 1998-02-01 [2009-07-08]. 
  16. ^ Sam Baldwin. Skiers vs Snowboaders: The Dying Feud. SnowSphere.com. January 2006 [2009-07-08]. 
  17. ^ Snowmobiling Facts. International Snowmobile Manufacturers Associations. 2006 [2007-04-23]. 
  18. ^ Jeffrey Selingo. Machines Let Resorts Please Skiers When Nature Won't. New York Times. 2001-02-08 [2009-07-08]. 
  19. ^ Washington Trails Association. Winter Hiking and Avalanche Danger. 2007-12-05 [2009-07-10]. 
  20. ^ Michelle Geinow. Cold Comfort: On the Cultural Significance of the Snowball in Baltimore. The City Paper. 1996-09-18 [2009-07-10]. 
  21. ^ Mary Mapes Dodge. St. Nicholas. University of Michigan. 1907: 241 [2009-07-10]. ISBN 0-217-84993-8. 
  22. ^ Adam Forrest. Snow sundayherald briefing. The Sunday Herald. January 6, 2008 [2009-07-07]. 
  23. ^ Michigan Technological University. A Frigid Place Gets a Blast From Space. 2009-05-27 [2009-07-10]. 
  24. ^ Jason Gabak. Snow softball a slippery sport. The Citizen. 2008-02-23 [2009-07-10]. 
  25. ^ Anne Minard. "Diamond Dust" Snow Falls Nightly on Mars. National Geographic News. 2009-07-02. 
  26. ^ Carolina Martinez. Massive Mountain Range Imaged on Saturn's Moon Titan. NASA. 2006-12-12. 
  27. ^ Carolyn Jones Otten. 'Heavy metal' snow on Venus is lead sulfide. Washington University in St Louis. 2004 [2007-08-21]. 

媒體

外部連結


基礎條目（30KB或以上）雪(46054) en:snow 基礎條目（30KB或以上）User:Towerman/translation/雪(65431)

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