Editing Death Valley (section)

==Climate==
[[File:Death Valley landscape.jpg|thumb|Landscape of Death Valley deserted land]]
Death Valley has a [[subtropical]], [[hot desert climate]] ([[Köppen climate classification|Köppen]]: ''BWh''), with long, extremely hot summers; short, warm winters; and little rainfall.

The valley is extremely dry because it lies in the [[rain shadow]] of four major mountain ranges (including the [[Sierra Nevada]] and [[Panamint Range]]). Moisture moving inland from the Pacific Ocean must pass eastward over the mountains to reach Death Valley; as air masses are forced upward by each range, they cool and moisture condenses, to fall as rain or snow on the western slopes. When the air masses reach Death Valley, most of the moisture in the air has already been lost and thus there is little left to fall as precipitation.<ref name=":0">{{Cite journal|last1=Roof|first1=Steven|last2=Callagan|first2=Charlie|title=The Climate of Death Valley, California|year=2003|url=http://stormbruiser.com/chase/wp-content/uploads/2013/08/bams-84-12-1725.pdf|archive-url=https://web.archive.org/web/20190421230215/http://stormbruiser.com/chase/wp-content/uploads/2013/08/bams-84-12-1725.pdf|archive-date=April 21, 2019|url-status=live|journal=Bulletin of the American Meteorological Society|volume=84|issue=12|pages=1725–1739|doi=10.1175/bams-84-12-1725|bibcode=2003BAMS...84.1725R}}</ref>

The extreme heat of Death Valley is attributable to a confluence of geographic and topographic factors. Scientists have identified a number of key contributors:<ref name=":0" />

* '''Solar heating''': The valley's surface (consisting of soil, rocks, sand, etc.) undergoes intense [[Solar irradiance#Irradiance on Earth's surface|solar heating]] because the air is clear and dry, and the land is dark and sparsely vegetated. This is especially noticeable in mid-summer, when the sun is nearly directly overhead.
* '''Trapping of warm air:''' Warm air naturally rises and cools;<ref>{{Cite web|url=https://medium.com/@barrywfischer/https-medium-com-barrywfischer-why-is-it-colder-at-higher-elevations-52f6c98544ca|title=Why is it colder at higher elevations? A thorough and visual explanation.|last=Fischer|first=Barry|date=December 20, 2018|website=Medium}}</ref> in Death Valley this air is subject to continual reheating as it is trapped by high, steep valley walls and recycled back to the valley floor.<ref>{{Cite web|url=https://www.nps.gov/deva/learn/nature/weather-and-climate.htm|title=Death Valley Weather|publisher=US National Park Service}}</ref> Warm air also is trapped by the valley's north–south orientation, which runs perpendicular to [[Westerlies|prevailing west-to-east winds]].
* '''Migration of warm air from other areas ([[advection]]):''' Warm desert regions adjacent to Death Valley, especially to the south and east, often heat air before it arrives in Death Valley.
* '''Warm mountain winds:''' As winds are forced up and over mountains (e.g. the numerous ranges west of Death Valley), the winds can be warmed in several ways. The resulting dry, warm winds are known as [[foehn wind]]s. Their warmth can in part be caused by the release of latent heat, which occurs when water vapor condenses into clouds. The extremely low elevation below sea level compresses the air which heats it further.

Severe heat and dryness contribute to perpetual drought-like conditions in Death Valley and prevent much cloud formation from passing through the confines of the valley, where precipitation is often in the form of a [[virga]].<ref name="weather">{{cite web|work=Death Valley National Park|title=Weather and Climate|url=http://www.nps.gov/deva/naturescience/weather-and-climate.htm|publisher=U.S. National Park Service|date=May 23, 2008|access-date=April 16, 2009}}</ref>

The depth and shape of Death Valley strongly influence its climate. The valley is a long, narrow basin that descends below sea level and is walled by high, steep mountain ranges. The clear, dry air and sparse plant cover allow sunlight to heat the desert surface. Summer nights provide little relief: overnight lows may dip just into the {{convert|82|to|98|F|C}} range. Moving masses of super-heated air blow through the valley, creating extremely high ambient temperatures.<ref name="National Park Service">{{cite web|work=Death Valley|title=Weather and Climate|url=http://www.nps.gov/deva/planyourvisit/upload/Weather%20and%20Climate.pdf|archive-url=https://web.archive.org/web/20061011102522/http://www.nps.gov/deva/planyourvisit/upload/Weather%20and%20Climate.pdf|archive-date=October 11, 2006|url-status=live|publisher=National Park Service|access-date=May 29, 2009}}</ref>
[[File:Death Valley Mesquite Flats Sand Dunes 2013.jpg|thumb|left|upright=1.3|[[Places of interest in the Death Valley area#Mesquite Flat Sand Dunes|Sand dunes at Mesquite Flats]]]]

The hottest air temperature ever recorded in Death Valley was {{convert|134|°F|1}}, on July 10, 1913, at [[Furnace Creek, California|Greenland Ranch]] (now [[Furnace Creek, California|Furnace Creek]]),<ref name="El_Azizia" /> which, as of today, is the highest atmospheric temperature ever recorded on the Earth's surface.<ref name=WorldHighTemp /> (A report of a temperature of {{convert|58|C|F}} in Libya in 1922 was later determined to be inaccurate.)<ref name="El_Azizia" /> During the heat wave that peaked with that record, five consecutive days reached {{convert|129|°F}} or higher. Some modern meteorologists now dispute the accuracy of the 1913 temperature measurement.<ref>{{cite web|url=https://www.wunderground.com/blog/JeffMasters/historic-heat-wave-reponsible-for-death-valleys-129f-gradually-weak.html|publisher=Wunderground|first=Jeff|last=Masters|work=WunderBlog|title=Historic Heat Wave {{sic|Repon|sible|nolink=y}} for Death Valley's {{convert|129|°F|°C|abbr=on}} Gradually Weakening|url-status=dead|archive-url=https://web.archive.org/web/20131105060318/http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2451|archive-date=November 5, 2013}}</ref> On June 30, 2013, a verified temperature of {{convert|129.2|F}} was recorded and is tied with [[Mitribah]], [[Kuwait]], for the hottest reliably measured air temperature ever recorded on Earth.<ref>{{cite news|url=https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/10/25/new-analysis-shreds-claim-that-death-valley-recorded-earths-hottest-temperature-in-1913/|title=New analysis shreds claim that Death Valley recorded Earth's highest temperature in 1913|last=Sumenow|first=Jason|date=October 25, 2016|url-status=live|newspaper=The Washington Post|archive-url=https://web.archive.org/web/20161027134608/https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/10/25/new-analysis-shreds-claim-that-death-valley-recorded-earths-hottest-temperature-in-1913/|archive-date=October 27, 2016}}</ref> A temperature of {{convert|130|°F|1}} was recorded at the Furnace Creek weather station on August 16, 2020, but has not yet been officially verified.<ref name="2020 record">{{cite web|url=https://www.theguardian.com/us-news/2020/aug/17/death-valley-temperature-rises-to-544c-possibly-the-hottest-ever-reliably-recorded|title=Death Valley temperature rises to 54.4C – possibly the hottest ever reliably recorded|author=Graham Readfearn|work=The Guardian|date=August 17, 2020}}</ref><ref>{{cite web|url=https://www.bbc.com/news/world-us-canada-53788018|title='Highest temperature on Earth' as Death Valley, US hits 54.4C|publisher=BBC News|date=August 17, 2020|access-date=July 30, 2021|url-status=live|archive-url=https://web.archive.org/web/20200817171540/https://www.bbc.com/news/world-us-canada-53788018|archive-date=August 17, 2020}}</ref> The valley again recorded that temperature on July 9, 2021;<ref>{{Cite tweet|number=1413659717126160390|user=NWSVegas|title=DEATH VALLEY UPDATE Thermometer High temp at Death Valley today = 130F. Warning sign If this says anything about how hot SAT-SUN will be, HEED THESE WARNINGS. Do not put yourself, nor first responders in danger this weekend! This observed high temp is considered preliminary & not yet validated.|author=NWS Las Vegas}}</ref><ref>{{cite web|url=https://yaleclimateconnections.org/2021/07/death-valley-california-breaks-the-all-time-world-heat-record-for-the-second-year-in-a-row/|title=Death Valley, California, breaks the all-time world heat record for the second year in a row|author=<!--Not stated-->|date=July 12, 2021|website=yaleclimateconnections.org|publisher=Yale climate connections|access-date=September 1, 2021}}</ref> however, that temperature has not yet been officially verified either.<ref>{{cite web|url=https://yaleclimateconnections.org/2021/07/death-valley-california-breaks-the-all-time-world-heat-record-for-the-second-year-in-a-row/|title=Death Valley, California, breaks the all-time world heat record for the second year in a row|author=<!--Not stated-->|date=July 12, 2021|website=yaleclimateconnections.org|publisher=Yale climate connections|access-date=September 1, 2021}}</ref> The valley's lowest temperature, recorded at Greenland Ranch (now Furnace Creek) on January 2, 1913, was {{convert|15|°F}}.<ref>{{cite web|url=http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca3603|publisher=Desert Research Institute|author=WRCC|work=Greenland Ranch, California|title=Period of Record General Climate Summary – Temperature|access-date=June 17, 2011}}</ref>

The highest surface temperature ever recorded in Death Valley was {{convert|201.0|°F|1}}, on July 15, 1972, at [[Furnace Creek, California|Furnace Creek]], which is the highest ground surface temperature ever recorded on earth, as well as the only recorded surface temperature of above {{convert|200|°F|1}}.<ref name="GroundTemp">{{cite journal|last1=Kubecka|first1=Paul|year=2001|title=A possible world record maximum natural ground surface temperature|journal=Weather|volume=56|issue=7|pages=218–221|doi=10.1002/j.1477-8696.2001.tb06577.x|bibcode=2001Wthr...56..218K|s2cid=120698040}}</ref>

The greatest number of consecutive days with a maximum temperature of at least {{convert|100|°F}} was 154, in the summer of 2001. The summer of 1996 had 40 days over {{convert|120|°F}}, and 105 days over {{convert|110|°F}}. The summer of 1917 had 52 days when the temperature reached {{convert|120|°F}} or above, 43 of them consecutive.

[[File:Badwater Desolation.jpg|thumb|View from [[Badwater Basin]]]]

The highest overnight or low temperature recorded in Death Valley is {{convert|110|°F|0}}, recorded on July 5, 1918.<ref>{{cite web|url=http://www.wrh.noaa.gov/vef/climate/DeathValleyClimateBook/July%20Normal%20and%20Record%20Temperatures.pdf|archive-url=https://web.archive.org/web/20150417051253/http://www.wrh.noaa.gov/vef/climate/DeathValleyClimateBook/July%20Normal%20and%20Record%20Temperatures.pdf|archive-date=April 17, 2015|url-status=live|title=July Daily Normals And Records|work=The Death Valley Climate Book|publisher=[[National Weather Service]]|access-date=March 26, 2017}}</ref> However, this value is disputed; a record high low of {{convert|107|°F|0}} on July 12, 2012, is considered reliable.<ref name=wu>{{cite web|title=Death Valley records a low of 107&nbsp;°F (41.7&nbsp;°C): a world record|first=Jeff|last=Masters|date=July 16, 2013|work=Weather Underground|url=http://www.wunderground.com/blog/JeffMasters/article.html?entrynum=2153|archive-url=https://web.archive.org/web/20130507235845/http://www.wunderground.com/blog/JeffMasters/article.html?entrynum=2153|archive-date=May 7, 2013|url-status=dead}}</ref> This is one of the highest values ever recorded.<ref>{{cite web|last1=Masters|first1=Jeff|author-link1=Jeff Masters|title=A World Record Low Humidity? {{convert|116|°F|°C|abbr=on}} With a 0.36% Humidity in Iran by Dr. Jeff Masters {{!}} Category 6|url=https://www.wunderground.com/cat6/world-record-low-humidity-116f-036-humidity-iran|website=[[Weather Underground]]|access-date=June 10, 2018|date=June 21, 2017}}</ref> Also on July 12, 2012, the mean 24-hour temperature recorded at Death Valley was {{convert|117.5|°F|1}}, which makes it the world's warmest 24-hour temperature on record.<ref>{{cite web|author=Jeff Masters|work=Blog|title=Death Valley records a low of 107&nbsp;°F (41.7&nbsp;°C): a world record|url=http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2153|publisher=[[Weather Underground]]|access-date=September 19, 2012}}</ref> July 2024 was the hottest month ever recorded in Death Valley, with a mean daily average temperature over the month of {{convert|108.5|°F|1}}.<ref name=DeathValleyHottestMonthEver>{{cite web|url=https://www.weather.gov/wrh/Climate?wfo=vef|title=Almanac for DEATH VALLEY NATIONAL PARK, CA – July 31, 2024|publisher=[[National Weather Service]]|date=August 1, 2024|access-date=August 1, 2024}}</ref>

Four major mountain ranges lie between Death Valley and the ocean, each one adding to an increasingly drier [[rain shadow]] effect, and in 1929, 1953, and 1989, no rain was recorded for the whole year.<ref name="National Park Service"/> The period from 1931 to 1934 was the driest stretch on record, with only {{convert|0.64|in|mm}} of rain over a 40-month period.<ref name="weather"/>
The average annual precipitation in Death Valley is {{convert|2.36|in|mm}}, while the Greenland Ranch station averaged {{convert|1.58|in|abbr=on}}.<ref>{{cite web|author=WRCC|title=Monthly Climate Summary|url=http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca3603|publisher=Desert Research Institute|access-date=June 8, 2009}}</ref> The wettest month on record is January 1995, when {{convert|2.59|in|mm}} fell on Death Valley.<ref name="weather"/> The wettest period on record was mid-2004 to mid-2005, in which nearly {{convert|6|in|mm|-1}} of rain fell in total, leading to [[ephemeral lake]]s in the valley and the region and tremendous wildflower blooms.<ref name="NPR.org">{{cite web|url=https://www.npr.org/templates/story/story.php?storyId=4521310|title=Wet Winter Brings Life to Death Valley|publisher=[[NPR]]}}</ref> Snow with accumulation has only been recorded in January 1922, while scattered flakes have been recorded on other occasions.

{{Weather box
| width = auto
| location = Death Valley National Park, California, 1991–2020 normals,{{efn|Mean maxima and minima (i.e. the highest and lowest temperature readings during an entire month or year) calculated based on data at said location from 1991 to 2020.}} extremes 1911–present
| single line = Y
| Jan record high F = 90
| Feb record high F = 97
| Mar record high F = 104
| Apr record high F = 113
| May record high F = 122
| Jun record high F = 129
| Jul record high F = 134
| Aug record high F = 130
| Sep record high F = 127
| Oct record high F = 114
| Nov record high F = 98
| Dec record high F = 89
| year record high F = 134
| Jan avg record high F = 78.4
| Feb avg record high F = 85.1
| Mar avg record high F = 95.4
| Apr avg record high F = 106.0
| May avg record high F = 113.6
| Jun avg record high F = 122.0
| Jul avg record high F = 125.9
| Aug avg record high F = 124.0

| Sep avg record high F = 118.1
| Oct avg record high F = 106.2
| Nov avg record high F = 90.0
| Dec avg record high F = 77.8
| year avg record high F = 126.7
| Jan high F = 67.2
| Feb high F = 73.7
| Mar high F = 82.6
| Apr high F = 91.0
| May high F = 100.7
| Jun high F = 111.1
| Jul high F = 117.4
| Aug high F = 115.9
| Sep high F = 107.7
| Oct high F = 93.3
| Nov high F = 77.4
| Dec high F = 65.6
| year high F = 92.0
| Jan mean F = 54.9
| Feb mean F = 61.3
| Mar mean F = 69.8
| Apr mean F = 77.9
| May mean F = 87.8
| Jun mean F = 97.5
| Jul mean F = 104.2
| Aug mean F = 102.3
| Sep mean F = 93.4
| Oct mean F = 78.9
| Nov mean F = 64.0
| Dec mean F = 53.4
| year mean F = 78.8
| Jan low F = 42.5
| Feb low F = 49.0
| Mar low F = 57.1
| Apr low F = 64.8
| May low F = 75.0
| Jun low F = 84.0
| Jul low F = 91.0
| Aug low F = 88.7
| Sep low F = 79.1
| Oct low F = 64.4
| Nov low F = 50.5
| Dec low F = 41.1
| year low F = 65.6
| Jan avg record low F = 30.5
| Feb avg record low F = 36.1
| Mar avg record low F = 42.8
| Apr avg record low F = 49.8
| May avg record low F = 58.5
| Jun avg record low F = 67.9
| Jul avg record low F = 78.3
| Aug avg record low F = 75.3
| Sep avg record low F = 65.4
| Oct avg record low F = 49.5
| Nov avg record low F = 35.9
| Dec avg record low F = 29.0
| year avg record low F = 28.0
| Jan record low F = 15
| Feb record low F = 20
| Mar record low F = 26
| Apr record low F = 35
| May record low F = 42
| Jun record low F = 49
| Jul record low F = 62
| Aug record low F = 65
| Sep record low F = 41
| Oct record low F = 32
| Nov record low F = 24
| Dec record low F = 19
| year record low F = 15
| precipitation color = green
| Jan precipitation inch = 0.37
| Feb precipitation inch = 0.52
| Mar precipitation inch = 0.25
| Apr precipitation inch = 0.10
| May precipitation inch = 0.03
| Jun precipitation inch = 0.05
| Jul precipitation inch = 0.10
| Aug precipitation inch = 0.10
| Sep precipitation inch = 0.20
| Oct precipitation inch = 0.12
| Nov precipitation inch = 0.10
| Dec precipitation inch = 0.26
| year precipitation inch = 2.20
| unit precipitation days = 0.01 inch
| Jan precipitation days = 2.4
| Feb precipitation days = 2.9
| Mar precipitation days = 2.0
| Apr precipitation days = 1.1
| May precipitation days = 0.9
| Jun precipitation days = 0.3
| Jul precipitation days = 1.1
| Aug precipitation days = 0.9
| Sep precipitation days = 0.8
| Oct precipitation days = 1.1
| Nov precipitation days = 0.9
| Dec precipitation days = 1.6
| year precipitation days = 16.0
| Jan snow inch = 
| Feb snow inch = 
| Mar snow inch = 
| Apr snow inch = 
| May snow inch = 
| Jun snow inch = 
| Jul snow inch = 
| Aug snow inch = 
| Sep snow inch = 
| Oct snow inch = 
| Nov snow inch = 
| Dec snow inch = 
| year snow inch = 
| unit snow days = 0.1 in
| Jan snow days = 
| Feb snow days = 
| Mar snow days = 
| Apr snow days = 
| May snow days = 
| Jun snow days = 
| Jul snow days = 
| Aug snow days = 
| Sep snow days = 
| Oct snow days = 
| Nov snow days = 
| Dec snow days = 
| year snow days = 
| source 1 = NOAA<ref>{{cite web|url=https://www.weather.gov/wrh/climate?wfo=vef|title=NOWData – NOAA Online Weather Data|publisher=[[National Oceanic and Atmospheric Administration]]|access-date=October 11, 2021}}</ref><ref>{{cite web|url=https://www.ncei.noaa.gov/access/services/data/v1?dataset=normals-monthly-1991-2020&startDate=0001-01-01&endDate=9996-12-31&stations=USC00042319&format=pdf|title=Summary of Monthly Normals 1991–2020|publisher=[[National Oceanic and Atmospheric Administration]]|access-date=June 12, 2021}}</ref> (September record high)<ref>{{cite web|url=https://www.cbsnews.com/losangeles/news/death-valley-127-degrees-record-hottest-september-day-on-the-planet/|title=Death Valley hits 127 degrees, setting record for hottest September day on the planet|publisher=CBS News|access-date=September 2, 2022}}
</ref>
| source = 
}}

{{Weather box|width=auto
| location = Death Valley (Cow Creek Station)
| single line = Y 
|collapsed = Y
| Jan record high F = 84
| Feb record high F = 89
| Mar record high F = 100
| Apr record high F = 110
| May record high F = 120
| Jun record high F = 125
| Jul record high F = 126
| Aug record high F = 125
| Sep record high F = 123
| Oct record high F = 111
| Nov record high F = 95
| Dec record high F = 84
| year record high F = 126
| Jan high F = 64.4
| Feb high F = 71.6
| Mar high F = 80.6
| Apr high F = 90.9
| May high F = 100.0
| Jun high F = 109.3
| Jul high F = 116.0
| Aug high F = 113.8
| Sep high F = 106.9
| Oct high F = 92.1
| Nov high F = 75.4
| Dec high F = 65.9
| year high F = 90.6
| Jan mean F = 52.5
| Feb mean F = 59.1
| Mar mean F = 67.4
| Apr mean F = 77.5
| May mean F = 86.4
| Jun mean F = 95.3
| Jul mean F = 102.1
| Aug mean F = 99.9
| Sep mean F = 92.1
| Oct mean F = 78.1
| Nov mean F = 62.3
| Dec mean F = 54.1
| year mean F = 77.2
| Jan low F = 40.6
| Feb low F = 46.6
| Mar low F = 54.3
| Apr low F = 64.1
| May low F = 72.7
| Jun low F = 81.2
| Jul low F = 88.4
| Aug low F = 86.0
| Sep low F = 77.4
| Oct low F = 64.0
| Nov low F = 49.3
| Dec low F = 42.4
| year low F = 63.9
| Jan record low F = 19
| Feb record low F = 30
| Mar record low F = 33
| Apr record low F = 45
| May record low F = 52
| Jun record low F = 54
| Jul record low F = 69
| Aug record low F = 69
| Sep record low F = 57
| Oct record low F = 40
| Nov record low F = 32
| Dec record low F = 27
| year record low F = 19
| precipitation color = green
| Jan precipitation inch = 0.24
| Feb precipitation inch = 0.32
| Mar precipitation inch = 0.20
| Apr precipitation inch = 0.20
| May precipitation inch = 0.10
| Jun precipitation inch = 0.02
| Jul precipitation inch = 0.10
| Aug precipitation inch = 0.11
| Sep precipitation inch = 0.12
| Oct precipitation inch = 0.11
| Nov precipitation inch = 0.20
| Dec precipitation inch = 0.29
| year precipitation inch = 2.00
| source 1 = Western Regional Climate Center<ref>{{cite web|title=Cow Creek, California, Monthly Climate Summary, 1934–1961|url=https://wrcc.dri.edu/cgi-bin/cliRECtM.pl?ca2092|publisher=Western Regional Climate Center, Desert Research Institute|access-date=June 8, 2019|url-status=live|archive-url=https://web.archive.org/web/20190505111204/https://wrcc.dri.edu/cgi-bin/cliRECtM.pl?ca2092|archive-date=May 5, 2019}}</ref>
|date = August 2010
}}
{{Graph:Weather monthly history
| table=ncei.noaa.gov/weather/Death Valley.tab
| title=Death Valley monthly weather statistics
}}

===Flooding===
[[File:Lake Badwater, Death Valley, 2005.jpg|thumb|A [[Landsat 5]] satellite photo of Lake Badwater on February 9, 2005]]
[[File:Badwater tm5 2007046.jpg|thumb|A Landsat 5 satellite photo of [[Badwater Basin]] [[dry lake]] on February 15, 2007]]

In 2005, Death Valley received four times its average annual rainfall of {{convert|1.5|in|mm}}. As it has done before for hundreds of years, the lowest spot in the valley filled with a wide, shallow lake, but the extreme heat and aridity immediately began evaporating the [[ephemeral lake]].

The pair of images (seen at right) from NASA's [[Landsat 5]] satellite documents the short history of Death Valley's [[Lake Badwater]]: formed in February 2005 (top) and evaporated by February 2007 (bottom). In 2005, a big pool of greenish water stretched most of the way across the valley floor. By May 2005, the valley floor had resumed its more familiar role as [[Badwater Basin]], salt-coated [[Salt pan (geology)|salt flats]]. In time, this freshly dissolved and recrystallized salt will darken.<ref>Daley, Jason (2019). [https://www.smithsonianmag.com/smart-news/flooding-creates-10-mile-long-lake-death-valley-180971699/ Flooding Creates a 10-Mile-Long Lake in Death Valley]. Smithsonian Magazine. Retrieved June 29, 2020.</ref>

The western margin of Death Valley is traced by [[alluvial fan]]s. During [[flash flood]]s, rainfall from the steep mountains to the west pours through narrow canyons, picking up everything from fine clay to large rocks. When these torrents reach the mouths of the canyons, they widen and slow, branching out into distributary channels. The paler the fans, the younger they are.