Editing Albedo (section)

===Snow===
Snow albedo is highly variable, ranging from as high as 0.9 for freshly fallen snow, to about 0.4 for melting snow, and as low as 0.2 for dirty snow.<ref>{{cite book |last1=Hall |first1=Dorothy K. |author-link=Dorothy Hall (scientist)|title=Remote Sensing of Ice and Snow |date=1985 |publisher=Springer Netherlands |location=Dordrecht |isbn=978-94-009-4842-6}}</ref> Over [[Antarctica]], snow albedo averages a little more than 0.8. If a marginally snow-covered area warms, snow tends to melt, lowering the albedo, and hence leading to more snowmelt because more radiation is being absorbed by the snowpack (referred to as the [[Ice–albedo feedback|ice–albedo]] [[positive feedback]]).

In [[Switzerland]], the citizens have been protecting their glaciers with large white tarpaulins to slow down the ice melt. These large white sheets are helping to reject the rays from the sun and defecting the heat. Although this method is very expensive, it has been shown to work, reducing snow and ice melt by 60%.<ref>{{Cite web |last=swissinfo.ch/gw |date=2021-04-02 |title=Glacier tarpaulins an effective but expensive shield against heat |url=https://www.swissinfo.ch/eng/sci-&-tech/glacier-tarpaulins-an-effective-but-expensive-shield-against-heat/46501004 |access-date=2024-02-20 |website=SWI swissinfo.ch |language=en-GB}}</ref>

Just as fresh snow has a higher albedo than does dirty snow, the albedo of snow-covered sea ice is far higher than that of sea water. Sea water absorbs more [[solar radiation]] than would the same surface covered with reflective snow. When sea ice melts, either due to a rise in sea temperature or in response to increased solar radiation from above, the snow-covered surface is reduced, and more surface of sea water is exposed, so the rate of energy absorption increases. The extra absorbed energy heats the sea water, which in turn increases the rate at which sea ice melts. As with the preceding example of snowmelt, the process of melting of sea ice is thus another example of a positive feedback.<ref>"All About Sea Ice." National Snow and Ice Data Center. Accessed 16 November 2017. /cryosphere/seaice/index.html.</ref> Both positive feedback loops have long been recognized as important for [[global warming]].{{citation needed|date=January 2018}}

[[Cryoconite]], powdery windblown [[dust]] containing soot, sometimes reduces albedo on glaciers and ice sheets.<ref name="Nat. Geo">[http://ngm.nationalgeographic.com/2010/06/melt-zone/jenkins-text/3 "Changing Greenland – Melt Zone"] {{Webarchive|url=https://web.archive.org/web/20160303175416/http://ngm.nationalgeographic.com/2010/06/melt-zone/jenkins-text/3 |url2=https://archive.wikiwix.com/cache/20110806084123/http://ngm.nationalgeographic.com/2010/06/melt-zone/jenkins-text/3 |date=3 March 2016 |date2= 6 August 2011}} page 3, of 4, article by Mark Jenkins in ''[[National Geographic (magazine)|National Geographic]]'' June 2010, accessed 8 July 2010</ref>

The dynamical nature of albedo in response to positive feedback, together with the effects of small errors in the measurement of albedo, can lead to large errors in energy estimates. Because of this, in order to reduce the error of energy estimates, it is important to measure the albedo of snow-covered areas through [[remote sensing]] techniques rather than applying a single value for albedo over broad regions.{{citation needed|date=January 2018}}