***An American in Paris*** is a [jazz-influenced](Jazz "wikilink") [symphonic poem](symphonic_poem "wikilink") (or [tone poem](tone_poem "wikilink"))[^1] for orchestra by American composer [George Gershwin](George_Gershwin "wikilink") first performed in 1928. It was inspired by the time that Gershwin had spent in [Paris](Paris "wikilink") and evokes the sights and energy of the French capital during the *`{{Lang|fr|[[Années folles]]}}`*.

Gershwin scored the piece for the standard instruments of the [symphony orchestra](symphony_orchestra "wikilink") plus [celesta](celesta "wikilink"), saxophones, and automobile horns. He brought back four Parisian taxi horns for the New York premiere of the composition, which took place on December 13, 1928, in [Carnegie Hall](Carnegie_Hall "wikilink"), with [Walter Damrosch](Walter_Damrosch "wikilink") conducting the [New York Philharmonic](New_York_Philharmonic "wikilink").[^2][^3] It was Damrosch who had commissioned Gershwin to write his [Concerto in F](Concerto_in_F_(Gershwin) "wikilink") following the earlier success of *[Rhapsody in Blue](Rhapsody_in_Blue "wikilink")* (1924).[^4] He completed the orchestration on November 18, less than four weeks before the work\'s premiere.[^5] He collaborated on the original program notes with critic and composer [Deems Taylor](Deems_Taylor "wikilink").[^6][^7][^8]

## Background

Although the story is likely apocryphal,[^9] Gershwin is said to have been attracted by [Maurice Ravel](Maurice_Ravel "wikilink")\'s unusual chords, and Gershwin went on his first trip to Paris in 1926 ready to study with Ravel. After his initial student audition with Ravel turned into a sharing of musical theories, Ravel said he could not teach him, saying, \"Why be a second-rate Ravel when you can be a first-rate Gershwin?\"[^10]

Gershwin strongly encouraged Ravel to come to the United States for a tour. To this end, upon his return to New York, Gershwin joined the efforts of Ravel\'s friend [Robert Schmitz](E._Robert_Schmitz "wikilink"), a pianist Ravel had met during the war, to urge Ravel to tour the U.S. Schmitz was the head of Pro Musica, promoting Franco-American musical relations, and was able to offer Ravel a \$10,000 fee for the tour, an enticement Gershwin knew would be important to Ravel.[^11]

Gershwin greeted Ravel in New York in March 1928 during a party held for Ravel\'s birthday by [Éva Gauthier](Éva_Gauthier "wikilink").[^12] Ravel\'s tour reignited Gershwin\'s desire to return to Paris, which he and his brother [Ira](Ira_Gershwin "wikilink") did after meeting Ravel.[^13] Ravel\'s high praise of Gershwin in an introductory letter to [Nadia Boulanger](Nadia_Boulanger "wikilink") caused Gershwin to seriously consider taking much more time to study abroad in Paris. Yet after he played for her, she told him she could not teach him. Boulanger gave Gershwin basically the same advice she gave all her accomplished master students: \"What could I give you that you haven\'t already got?\"[^14][^15] This did not set Gershwin back, as his real intent abroad was to complete a new work based on Paris and perhaps a second rhapsody for piano and orchestra to follow his *[Rhapsody in Blue](Rhapsody_in_Blue "wikilink")*. Paris at this time hosted many expatriate writers, among them [Ezra Pound](Ezra_Pound "wikilink"), [W. B. Yeats](W._B._Yeats "wikilink"), [Ernest Hemingway](Ernest_Hemingway "wikilink"), [F. Scott Fitzgerald](F._Scott_Fitzgerald "wikilink") and artist [Pablo Picasso](Pablo_Picasso "wikilink").[^16]

## Composition

{{-}}
Gershwin based *An American in Paris* on a melodic fragment called \"Very Parisienne\",[^17] written in 1926 on his first visit to Paris as a gift to his hosts, Robert and Mabel Schirmer. Gershwin called it \"a rhapsodic ballet\"; it is written freely and in a much more modern idiom than his prior works.[^18]

Gershwin explained in *[Musical America](Musical_America "wikilink")*, \"My purpose here is to portray the impressions of an American visitor in Paris as he strolls about the city, listens to the various street noises, and absorbs the French atmosphere.\"[^19][^20]

The piece is structured into five sections, which culminate in a loose [A--B--A format](Ternary_form "wikilink"). Gershwin\'s first A episode introduces the two main \"walking\" themes in the \"Allegretto grazioso\" and develops a third theme in the \"Subito con brio\".[^21] The style of this A section is written in the typical French style of composers [Claude Debussy](Claude_Debussy "wikilink") and [Les Six](Les_Six "wikilink").[^22] This A section featured duple meter, singsong rhythms, and diatonic melodies with the sounds of oboe, English horn, and taxi horns. The B section\'s \"Andante ma con ritmo deciso\" introduces the American [Blues](Blues "wikilink") and spasms of homesickness. The \"Allegro\" that follows continues to express homesickness in a faster [twelve-bar blues](twelve-bar_blues "wikilink"). In the B section, Gershwin uses common time, syncopated rhythms, and bluesy melodies with the sounds of trumpet, saxophone, and snare drum. \"Moderato con grazia\" is the last A section that returns to the themes set in A. After recapitulating the \"walking\" themes, Gershwin overlays the slow blues theme from section B in the final \"Grandioso\".

## Response

Gershwin did not particularly like Walter Damrosch\'s interpretation at the world premiere of *An American in Paris*. He stated that Damrosch\'s sluggish, dragging tempo caused him to walk out of the hall during a matinee performance of this work. The audience, according to Edward Cushing, responded with \"a demonstration of enthusiasm impressively genuine in contrast to the conventional applause which new music, good and bad, ordinarily arouses.\"[^23]

Critics believed that *An American in Paris* was better crafted than Gershwin\'s [Concerto in F](Concerto_in_F_(Gershwin) "wikilink").[^24] *Evening Post* did not think it belonged in a program with classical composers [César Franck](César_Franck "wikilink"), [Richard Wagner](Richard_Wagner "wikilink"), or [Guillaume Lekeu](Guillaume_Lekeu "wikilink") on its premiere. Gershwin responded to the critics:

## Instrumentation

*An American in Paris* was originally scored for 3 [flutes](Western_concert_flute "wikilink") (3rd doubling on [piccolo](piccolo "wikilink")), 2 [oboes](oboe "wikilink"), [English horn](English_horn "wikilink"), 2 [clarinets](clarinet "wikilink") in [B-flat](soprano_clarinet "wikilink"), [bass clarinet](bass_clarinet "wikilink") in B-flat, 2 [bassoons](bassoon "wikilink"), 4 [horns](French_horn "wikilink") in F, 3 [trumpets](trumpet "wikilink") in B-flat, 3 [trombones](trombone "wikilink"), [tuba](tuba "wikilink"), [timpani](timpani "wikilink"), [snare drum](snare_drum "wikilink"), [bass drum](bass_drum "wikilink"), [triangle](Triangle_(musical_instrument) "wikilink"), [wood block](Woodblock_(instrument) "wikilink"), [ratchet](Ratchet_(instrument) "wikilink"), [cymbals](cymbal "wikilink"), low and high [tom-toms](Tom-tom_drum "wikilink"), [xylophone](xylophone "wikilink"), [glockenspiel](glockenspiel "wikilink"), [celesta](celesta "wikilink"), 4 [taxi horns](vehicle_horn "wikilink") labeled as A, B, C, and D with circles around them, [alto saxophone](alto_saxophone "wikilink"), [tenor saxophone](tenor_saxophone "wikilink"), [baritone saxophone](baritone_saxophone "wikilink") (all doubling [soprano](soprano_saxophone "wikilink") and alto saxophones), and [strings](String_section "wikilink").[^25][^26] Although most modern audiences have heard the taxi horns using the notes A, B, C, and D, it had been Gershwin\'s intention to use the notes A~[4](Scientific_pitch_notation "wikilink")~, B~4~, D~5~, and A~3~.[^27] It is likely that in labeling the taxi horns as A, B, C, and D with circles, he was referring to the four horns, and not the notes that they played.[^28]

A major revision of the work by composer and arranger F. Campbell-Watson simplified the instrumentation by reducing the saxophones to only three instruments: alto, tenor and baritone; the soprano and alto saxophone doublings were eliminated to avoid changing instruments. This became the standard performing edition until 2000, when Gershwin specialist [Jack Gibbons](Jack_Gibbons "wikilink") made his own restoration of the original orchestration of *An American in Paris*, working directly from Gershwin\'s original manuscript, including the restoration of Gershwin\'s soprano saxophone parts removed in Campbell-Watson\'s revision.[^29] Gibbons\' restored orchestration of *An American in Paris* was performed at London\'s Queen Elizabeth Hall on July 9, 2000, by the City of Oxford Orchestra conducted by Levon Parikian.[^30]

[William Daly](William_Merrigan_Daly "wikilink") arranged the score for piano solo; this was published by New World Music in 1929.[^31][^32]

## Preservation status {#preservation_status}

On September 22, 2013, it was announced that a musicological [critical edition](Historical_editions_(music) "wikilink") of the full orchestral score would be eventually released. The Gershwin family, working in conjunction with the [Library of Congress](Library_of_Congress "wikilink") and the [University of Michigan](University_of_Michigan "wikilink"), were working to make scores available to the public that represent Gershwin\'s true intent. It was unknown whether the critical score would include the four minutes of material Gershwin later deleted from the work (such as the restatement of the blues theme after the faster 12 bar blues section), or if the score would document changes in the orchestration during Gershwin\'s composition process.[^33]

The score to *An American in Paris* was scheduled to be issued first in a series of scores to be released. The entire project was expected to take 30 to 40 years to complete, but *An American in Paris* was planned to be an early volume in the series.[^34][^35]

Two [urtext editions](urtext_edition "wikilink") of the work were published by the German publisher B-Note Music in 2015. The changes made by Campbell-Watson were withdrawn in both editions. In the extended urtext, 120 bars of music were re-integrated. Conductor Walter Damrosch had cut them shortly before the first performance.[^36]

On September 9, 2017, The Cincinnati Symphony Orchestra gave the world premiere of the long-awaited critical edition of the piece prepared by Mark Clague, director of the Gershwin initiative at the University of Michigan. This performance was of the original 1928 orchestration.[^37]

## Recordings

*An American in Paris* has been frequently recorded.[^38] The first recording was made for the [Victor Talking Machine Company](Victor_Talking_Machine_Company "wikilink") in 1929 with [Nathaniel Shilkret](Nathaniel_Shilkret "wikilink") conducting the Victor Symphony Orchestra, drawn from members of the [Philadelphia Orchestra](Philadelphia_Orchestra "wikilink"). Gershwin was on hand to \"supervise\" the recording; however, Shilkret was reported to be in charge and eventually asked the composer to leave the recording studio. Then, a little later, Shilkret discovered there was no one to play the brief [celesta](celesta "wikilink") solo during the slow section, so he hastily asked Gershwin if he might play the solo; Gershwin said he could and so he briefly participated in the actual recording. This recording is believed to use the taxi horns in the way that Gershwin had intended using the notes A-flat, B-flat, a higher D, and a lower A.[^39]

The radio broadcast of the September 8, 1937, Hollywood Bowl George Gershwin Memorial Concert, in which *An American in Paris,* also conducted by Shilkret, was second on the program, was recorded and was released in 1998 in a two-CD set.

[Arthur Fiedler](Arthur_Fiedler "wikilink") and the [Boston Pops Orchestra](Boston_Pops_Orchestra "wikilink") recorded the work for RCA Victor, including one of the first stereo recordings of the music.

In 1945, [Arturo Toscanini](Arturo_Toscanini "wikilink") conducting the [NBC Symphony Orchestra](NBC_Symphony_Orchestra "wikilink") recorded the piece for [RCA Victor](RCA_Victor "wikilink"), one of the few commercial recordings Toscanini made of music by an American composer.[^40]

The [Seattle Symphony](Seattle_Symphony "wikilink") also recorded a version in 1990 of Gershwin\'s original score, before numerous edits were made resulting in the score as we hear it today.[^41]

The blues section of *An American in Paris* has been recorded separately by a number of artists; [Ralph Flanagan](Ralph_Flanagan "wikilink") & His Orchestra released it as a single in 1951 which reached No. 15 on the *Billboard* chart.[^42] [Harry James](Harry_James "wikilink") released a version of the blues section on his 1953 album *One Night Stand,* recorded live at the [Aragon Ballroom in Chicago](Aragon_Ballroom_(Chicago) "wikilink") ([Columbia](Columbia_Records "wikilink") GL 522 and CL 522).[^43]

## Use in film {#use_in_film}

In 1951, [Metro-Goldwyn-Mayer](Metro-Goldwyn-Mayer "wikilink") released the musical film *[An American in Paris](An_American_in_Paris_(film) "wikilink")*, featuring [Gene Kelly](Gene_Kelly "wikilink") and [Leslie Caron](Leslie_Caron "wikilink") and directed by [Vincente Minnelli](Vincente_Minnelli "wikilink"). Winning the [1951 Best Picture Oscar](24th_Academy_Awards "wikilink") and numerous other awards, the film featured many tunes of Gershwin and concluded with an extensive, elaborate dance sequence built around the symphonic poem *An American in Paris* (arranged for the film by [Johnny Green](Johnny_Green "wikilink")), which at the time was the most expensive musical number ever filmed, costing \$500,000 .[^44][^45]

## Notes and references {#notes_and_references}

## Further reading {#further_reading}

-

## External links {#external_links}

-

- [Scores](https://archives.nyphil.org/index.php/search?search-type=singleFilter&search-text=an+american+in+paris&doctype=printedMusic), marked by [Leonard Bernstein](Leonard_Bernstein "wikilink"), [Andre Kostelanetz](Andre_Kostelanetz "wikilink"), [Erich Leinsdorf](Erich_Leinsdorf "wikilink"); [New York Philharmonic](New_York_Philharmonic "wikilink") archives

- [1944 recording](https://archive.org/details/AnAmericanInParis) by the [New York Philharmonic](New_York_Philharmonic "wikilink") conducted by [Artur Rodziński](Artur_Rodziński "wikilink")

- , New York Philharmonic, [Leonard Bernstein](Leonard_Bernstein "wikilink"), 1959. [1](https://conifer.rhizome.org/Germinal/wikipedia/20180529043352/https://www.youtube.com/watch?v=zi0ENw-JlUI)

[Category:1928 compositions](Category:1928_compositions "wikilink") [Category:Compositions by George Gershwin](Category:Compositions_by_George_Gershwin "wikilink") [Category:Grammy Hall of Fame Award recipients](Category:Grammy_Hall_of_Fame_Award_recipients "wikilink") [Category:Music about Paris](Category:Music_about_Paris "wikilink") [Category:Music commissioned by the New York Philharmonic](Category:Music_commissioned_by_the_New_York_Philharmonic "wikilink") [Category:Symphonic poems](Category:Symphonic_poems "wikilink")

{{cite news |author=Staff |title=An American in Paris |url=https://theatricalia.com/play/e69/an-american-in-paris |date=April 1, 2017 |work=Theatricalia.com |url-status=live |archiveurl=https://archive.today/20230831150800/https://theatricalia.com/play/e69/an-american-in-paris |archivedate=August 31, 2023 |accessdate=August 31, 2023 }}
```

[^1]: ```
[^2]: ```
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[^40]: ```
[^41]: ```
[^42]: ```
[^43]: ```
[^45]: ```
{{cite web |url=http://nyphil.org/~/media/pdfs/program-notes/1314/Gershwin-An%20American%20in%20Paris.pdf |title=Rhapsody in Blue for Piano and Orchestra : An American in Paris |author=George Gershwin |website=Nyphil.org |access-date=April 6, 2016 |archive-url=https://web.archive.org/web/20160304052949/http://nyphil.org/~/media/pdfs/program-notes/1314/Gershwin-An%20American%20in%20Paris.pdf |archive-date=March 4, 2016 |url-status=dead }}
```

[^3]: [Alan Gilbert and the New York Philharmonic: Makoto Ozone to Perform Gershwin\'s *Rhapsody in Blue* in One-Night-Only Concert All-American Program Also to Include Bernstein\'s *Candide* Overture and Symphonic Dances from *West Side Story* Gershwin\'s *An American in Paris*: April 22, 2014 at nyphil.org](https://nyphil.org/~/media/pdfs/newsroom/1314/Releases/gilbert-ozone-final.pdf) Accessed June 20, 2017

[^4]: [\"*An American in Paris*\"](https://www.britannica.com/topic/An-American-in-Paris-by-Gershwin), by Betsy Schwarm, *[Encyclopædia Britannica](Encyclopædia_Britannica "wikilink")*

{{cite web | url = http://www.kennedy-center.org/calendar/?fuseaction=composition&composition_id=2983 | title = ''An American in Paris'': About the Work | publisher = [[The Kennedy Center]] | author=Richard Freed|author-link=Richard Freed| access-date=December 5, 2012}}
```

{{Cite book|title=The George Gershwin Reader|editor1-last=Wyatt|editor1-first=Robert|editor2-last=Johnson|editor2-first=John Andrew|date=2004|author=[[Deems Taylor]]|chapter=33. ''An American in Paris'': Narrative Guide" (1928)|doi=10.1093/acprof:oso/9780195327113.003.0033|pages=110–111|publisher=Oxford University Press|isbn=978-0-19-532711-3}}
```

{{Cite web |title=An American in Paris {{!}}
```
Runyan Program Notes \|url=<https://www.runyanprogramnotes.com/george-gershwin/american-paris> \|access-date=2022-12-12 \|website=www.runyanprogramnotes.com}}

{{Cite book |last=Pegolotti |first=James |url=https://books.google.com/books?id=Hg4HEAAAQBAJ&dq=deems+taylor+an+american+in+paris&pg=PA122 |title=Deems Taylor: Selected Writings |date=2020-10-28 |publisher=Routledge |isbn=978-1-000-10154-6}}
```

{{Cite book |last=Schwartz |first=Charles |url=https://archive.org/details/gershwinhislifem00sch_3az |title=George Gershwin: His Life and Music |date=1973 |isbn=0-672-51662-4 |url-access=registration|page=154|publisher=[[Bobbs-Merrill Company]]}}
```

{{Cite magazine |last=Schiff |first=David |author-link=David Schiff |date=October 1, 1998 |title=Misunderstanding Gershwin |url=https://www.theatlantic.com/magazine/archive/1998/10/misunderstanding-gershwin/377252/ |url-status=live |magazine=[[The Atlantic]] |archive-url=https://web.archive.org/web/20181215222801/https://www.theatlantic.com/magazine/archive/1998/10/misunderstanding-gershwin/377252/ |archive-date=Dec 15, 2018 |access-date=December 11, 2018 |url-access=subscription}}
```

{{Cite book |url=https://archive.org/details/bolerolifeofmaur1940goss |title=Bolero: the life of Maurice Ravel |last=Goss |first=Madeleine |publisher=New York, H. Holt and Company |year=1940 |pages=[https://archive.org/details/bolerolifeofmaur1940goss/page/216 216]–219}}
```

{{Cite web |url=https://csosoundsandstories.org/fascinatin-rhythm-when-ravel-met-gershwin-in-jazz-age-new-york/ |title=Fascinatin' rhythm: When Ravel met Gershwin in Jazz Age New York |last=Burton |first=Louise |date=May 26, 2015 |website=CSO Sounds & Stories |publisher=[[Chicago Symphony Orchestra]] |access-date=December 11, 2018 |archive-date=January 21, 2022 |archive-url=https://web.archive.org/web/20220121135409/https://csosoundsandstories.org/fascinatin-rhythm-when-ravel-met-gershwin-in-jazz-age-new-york/ |url-status=dead }}
```

[^13]:

{{cite book|url=https://books.google.com/books?id=_-VcUAeWQr0C&pg=PA71|title=Nadia Boulanger|author=Jérôme Spycket|publisher=Pendragon Press|year=1992|isbn=978-0-945193-38-8|pages=71–73}}
```

[^15]:

[^16]: LSRI Archives Oral Interview Anita Loos and Mary Anita Loos October 1979 re: letters and Ravel\'s telegram to Gershwin

{{Cite web |url=http://gershwin.com/publications/an-american-in-paris-concert-work/ |title=An American in Paris |website=Gershwin Enterprises |access-date=December 11, 2018 }}
```

{{cite book|url=https://archive.org/details/gershwinyearsgeo00jabl|url-access=registration|title=The Gershwin Years: George And Ira|author1=Edward Jablonski|author-link=Edward Jablonski|author2=Lawrence D. Stewart|publisher=Da Capo Press|year=1958|isbn=978-0-306-80739-8|pages=[https://archive.org/details/gershwinyearsgeo00jabl/page/138 138]–141}}
```

{{cite book|url=https://books.google.com/books?id=RySwdc151ZoC&pg=PA431|title=George Gershwin: His Life and Work|author=Howard Pollack|author-link=Howard Pollack|date=January 15, 2007|publisher=University of California Press|isbn=978-0-520-93314-9|pages=119, 431–440}}
```

{{Cite web |title=''An American in Paris'' performance material|url=https://www.schott-music.com/en/an-american-in-paris-no251041.html|access-date=2022-12-12|publisher=[[Schott Music]]}}
```

{{cite thesis|last=Van Dyke|first=Joseph M.|year=2011|title=George Gershwin's An American in Paris for Two Pianos: A Critical Score Study and Performance Guide|type=Doctoral thesis|location=Columbus, Ohio|publisher=OhioLINK Electronic Theses and Dissertations Center|url=https://etd.ohiolink.edu/pg_10?0::NO:10:P10_ACCESSION_NUM:osu1298660291|access-date=September 14, 2017|archive-date=September 14, 2017|archive-url=https://web.archive.org/web/20170914172912/https://etd.ohiolink.edu/pg_10?0::NO:10:P10_ACCESSION_NUM:osu1298660291|url-status=dead}}
```

[^22]:

{{Cite web |date=2013-09-08 |title=Who Could Ask For Anything More |url=https://smtd.umich.edu/ami/gershwin/?parallax-sections=who-could-ask-for-anything-more |access-date=2022-12-12 |website=The Gershwin Initiative Website}}
```

[^24]:

{{Cite web|url=http://archives.nyphil.org/index.php/artifact/47d1f79a-8ea6-4aba-964f-989cb5dc2cd7/fullview#page/4/mode/2up|title=George Gershwin: An American in Paris (original score)|website=New York Philharmonic Archives|archive-url=https://web.archive.org/web/20170904200637/http://archives.nyphil.org/index.php/artifact/47d1f79a-8ea6-4aba-964f-989cb5dc2cd7/fullview#page/4/mode/2up|archive-date=September 4, 2017|url-status=dead|access-date=September 4, 2017|df=mdy-all}}
```

{{Cite book|url=https://www.schott-music.com/en/preview/viewer/index/?idx=MjUxMDQx&idy=251041&dl=0|title=An American in Paris|author=George Gershwin|year=1930|type=full orchestral score|publisher=[[Chappell & Co.]]|location=London|access-date=2023-07-25|via=[[Schott Music]]}}
```

{{cite news|url=https://www.nytimes.com/2016/03/02/theater/have-we-been-playing-gershwin-wrong-for-70-years.html|title=Have We Been Playing Gershwin Wrong for 70 Years?|last=Cooper |first=Michael |date=March 1, 2016|newspaper=[[The New York Times]]|access-date=April 6, 2016 }}
```

{{cite web|url=http://www.music.umich.edu/ami/gershwin/?p=715 |last=Clague |first=Mark |title=1929 Gershwin Taxi Horn Photo Clarifies Mystery|publisher=[[University of Michigan School of Music, Theatre & Dance]]|date=March 5, 2016|access-date=April 6, 2016 }}
```

{{cite web|url= http://www.jackgibbons.com/reviews.htm|title=Musical Opinion review of Gershwin Spectacular|access-date=June 28, 2017 }}
```

[^30]:

{{Cite web |url=https://ljms.org/directory/ |title=CMS: ''An American in Paris'' Program Notes |last=Rodda |first=Richard E. |date=2013 |website=La Jolla Music Society |access-date=December 11, 2018 |archive-date=August 13, 2018 |archive-url=https://web.archive.org/web/20180813075416/https://ljms.org/directory |url-status=dead }}
```

{{Cite web |url=http://www.free-scores.com/download-sheet-music.php?pdf=82579 |title=Free sheet music : Gershwin, George – ''An American in Paris'' (Piano solo) |website=www.free-scores.com |access-date=December 11, 2018 }}
```

{{cite web|url=https://www.pbs.org/newshour/rundown/new-critical-edition-of-george-and-ira-gershwins-works-to-be-compiled/ |title=New, critical edition of George and Ira Gershwin's works to be compiled|work=[[PBS NewsHour]]|date=September 14, 2013 |access-date=April 6, 2016}}
```

{{cite web|url=http://www.music.umich.edu/ami/gershwin/?page_id=59 |title=The Editions » Gershwin |website=Music.umich.edu |date= September 8, 2013|access-date=April 6, 2016}}
```

{{cite web |url=http://musicologynow.ams-net.org/2013/09/george-and-ira-gershwin-critical-edition_20.html |title=Musicology Now: George and Ira Gershwin Critical Edition |website=Musicologynow.ams-net.org |date=September 17, 2013 |access-date=April 6, 2016 |archive-url=https://web.archive.org/web/20181215122523/http://musicologynow.ams-net.org/2013/09/george-and-ira-gershwin-critical-edition_20.html |archive-date=December 15, 2018 |url-status=dead }}
```

{{cite web |title=''An American in Paris'' Urtext | url=https://www.bnote.de/?set=werk_detail&kompid=246&bnnr=16963&lc=en|website=Bnote.de |access-date=December 14, 2015}}
```

{{cite web |url= https://www.eamdc.com/news/critical-edition-of-george-gershwins-an-american-in-paris-debuts-with-the-cincinnati-and-atlanta-symphony-orchestras/ |title= Critical Edition of George Gershwin's ''An American in Paris'' Debuts with the Cincinnati and Atlanta Symphony Orchestras |date=September 1, 2017 |access-date=July 18, 2021}}
```

{{Cite web |title=''An American in Paris'' by George Gershwin|url=https://www.whosampled.com/George-Gershwin/An-American-in-Paris/ |access-date=2022-12-12|website=[[WhoSampled]]}}
```

[^39]:

{{Cite book |last=Pollack |first=Howard |url=http://california.universitypressscholarship.com/view/10.1525/california/9780520248649.001.0001/upso-9780520248649 |title=George GershwinHis Life and Work |date=2007-01-15 |publisher=University of California Press |isbn=978-0-520-24864-9 |doi=10.1525/california/9780520248649.003.0023}}
```

{{cite news|last=Bargreen|first=Melinda|url=https://archive.seattletimes.com/archive/?date=19900628&slug=1079541|title=Recordings|newspaper=[[The Seattle Times]]|date=June 28, 1990|access-date=July 25, 2023}}
```

{{cite book |url=https://books.google.com/books?id=NP6OdDrutyAC&pg=PA22|title=Hit Records, 1950-1975|first= David F.|last= Lonergan |date= 2005|page=22 |isbn=9780810851290 |publisher=Scarecrow Press }}
```

{{Cite web |title=Columbia Album Discography (1951-55) |url=https://www.bsnpubs.com/columbia/columbia12/columbia500.html |access-date=2024-03-29 |website=www.bsnpubs.com}}
```

[^44]: The Eddie Mannix Ledger, Los Angeles: Margaret Herrick Library, Center for Motion Picture Study

{{Cite news|url=https://daily.jstor.org/american-paris-onstage-onscreen/|title=''An American in Paris'': Onstage and Onscreen {{!}}
```
JSTOR Daily\|date=May 19, 2015\|work=JSTOR Daily\|access-date=September 8, 2017}}
 View this article on [legacy Wikipedia](https://en.wikipedia.org/wiki/An_American_in_Paris)


![Albedo change in [Greenland](Greenland "wikilink"): The map shows the
difference between the amount of sunlight
[Greenland](Greenland "wikilink") reflected in the summer of 2011 versus
the average percent it reflected between 2000 and 2006. Some areas
reflect close to 20 percent less light than a decade
ago.[^1]](Greenland_Albedo_Change.png "Albedo change in Greenland: The map shows the difference between the amount of sunlight Greenland reflected in the summer of 2011 versus the average percent it reflected between 2000 and 2006. Some areas reflect close to 20 percent less light than a decade ago.")
**Albedo** ( ; ) is the fraction of [sunlight](sunlight "wikilink") that
is [diffusely reflected](Diffuse_reflection "wikilink") by a body. It is
measured on a scale from 0 (corresponding to a [black
body](black_body "wikilink") that absorbs all incident radiation) to 1
(corresponding to a body that reflects all incident radiation). *Surface
albedo* is defined as the ratio of
[radiosity](Radiosity_(radiometry) "wikilink") *J*e to the
[irradiance](irradiance "wikilink") *E*e (flux per unit area)
received by a surface.[^3] The proportion reflected is not only
determined by properties of the surface itself, but also by the spectral
and angular distribution of solar radiation reaching the Earth's
surface.[^4] These factors vary with atmospheric composition, geographic
location, and time (see [position of the
Sun](position_of_the_Sun "wikilink")).

While bi-hemispherical [reflectance](reflectance "wikilink") is
calculated for a single angle of incidence (i.e., for a given position
of the Sun), albedo is the directional integration of reflectance over
all solar angles in a given period. The temporal resolution may range
from seconds (as obtained from flux measurements) to daily, monthly, or
annual averages.

Unless given for a specific wavelength (spectral albedo), albedo refers
to the entire spectrum of solar radiation.[^5] Due to measurement
constraints, it is often given for the spectrum in which most solar
energy reaches the surface (between 0.3 and 3 μm). This spectrum
includes [visible light](visible_spectrum "wikilink") (0.4–0.7 μm),
which explains why surfaces with a low albedo appear dark (e.g., trees
absorb most radiation), whereas surfaces with a high albedo appear
bright (e.g., snow reflects most radiation).

[Ice–albedo feedback](Ice–albedo_feedback "wikilink") is a [positive
feedback](positive_feedback "wikilink") climate process where a change
in the area of [ice caps](ice_caps "wikilink"),
[glaciers](glaciers "wikilink"), and [sea ice](sea_ice "wikilink")
alters the albedo and surface temperature of a planet.
[Ice](Ice "wikilink") is very reflective, therefore it reflects far more
solar energy back to space than the other types of land area or open
water. Ice–albedo feedback plays an important role in global [climate
change](Climate_change_(general_concept) "wikilink").[^6] Albedo is an
important concept in [climate science](climate_science "wikilink").

## Terrestrial albedo

Sample albedos

Surface

Typical

albedo

Fresh asphalt

0.04<ref name="heat island">{{cite web

Open ocean

0.061

Worn asphalt

0.122

Conifer forest,

summer

0.08,<ref name="Betts 1">{{Cite journal

Deciduous
forest

0.15 to 0.183

Bare soil

0.17<ref name="markvart">{{Cite book

Green grass

0.254

Desert sand

0.40<ref name="Tetzlaff">{{Cite book

New concrete

0.555

Ocean ice

0.50 to 0.706

Fresh snow

0.807

Aluminum

0.8589

Thermodynamics: Albedo {{!}} National Snow and Ice Data
Center|website=nsidc.org|access-date=14 August 2016}}↩

↩

↩

Sample albedos

Any albedo in visible light falls within a range of about 0.9 for fresh
snow to about 0.04 for charcoal, one of the darkest substances. Deeply
shadowed cavities can achieve an effective albedo approaching the zero
of a [black body](black_body "wikilink"). When seen from a distance, the
ocean surface has a low albedo, as do most forests, whereas desert areas
have some of the highest albedos among landforms. Most land areas are in
an albedo range of 0.1 to 0.4.[^7] The average albedo of
[Earth](Earth "wikilink") is about 0.3.[^8] This is far higher than for
the ocean primarily because of the contribution of clouds.

Earth's surface albedo is regularly estimated via [Earth
observation](Earth_observation "wikilink") satellite sensors such as
[NASA](NASA "wikilink")'s [MODIS](MODIS "wikilink") instruments on board
the [Terra](Terra_(satellite) "wikilink") and
[Aqua](Aqua_(satellite) "wikilink") satellites, and the CERES instrument
on the [Suomi NPP](Suomi_NPP "wikilink") and
[JPSS](Joint_Polar_Satellite_System "wikilink"). As the amount of
reflected radiation is only measured for a single direction by
satellite, not all directions, a mathematical model is used to translate
a sample set of satellite reflectance measurements into estimates of
[directional-hemispherical
reflectance](directional-hemispherical_reflectance "wikilink") and
bi-hemispherical reflectance (e.g.,[^9]). These calculations are based
on the [bidirectional reflectance distribution
function](bidirectional_reflectance_distribution_function "wikilink")
(BRDF), which describes how the reflectance of a given surface depends
on the view angle of the observer and the solar angle. BDRF can
facilitate translations of observations of reflectance into albedo.

Earth's average surface temperature due to its albedo and the
[greenhouse effect](greenhouse_effect "wikilink") is currently about .
If Earth were frozen entirely (and hence be more reflective), the
average temperature of the planet would drop below .[^10] If only the
continental land masses became covered by glaciers, the mean temperature
of the planet would drop to about .[^11] In contrast, if the entire
Earth was covered by water – a so-called [ocean
planet](ocean_planet "wikilink") – the average temperature on the planet
would rise to almost .[^12]

In 2021, scientists reported that Earth dimmed by ~0.5% over two decades
(1998–2017) as measured by earthshine using modern photometric
techniques. This may have both been co-caused by [climate
change](climate_change "wikilink") as well as a substantial increase in
global warming. However, the link to climate change has not been
explored to date and it is unclear whether or not this represents an
ongoing trend.[^13][^14]

### White-sky, black-sky, and blue-sky albedo

For land surfaces, it has been shown that the albedo at a particular
[solar zenith angle](solar_zenith_angle "wikilink") *θ**i*
can be approximated by the proportionate sum of two terms:

- the [directional-hemispherical
  reflectance](directional-hemispherical_reflectance "wikilink") at that
  solar zenith angle, ${\bar \alpha(\theta_i)}$, sometimes referred to
  as black-sky albedo, and
- the [bi-hemispherical
  reflectance](bi-hemispherical_reflectance "wikilink"),
  $\bar{ \bar \alpha}$, sometimes referred to as white-sky albedo.

with ${1-D}$ being the proportion of direct radiation from a given solar
angle, and ${D}$ being the proportion of diffuse illumination, the
actual albedo ${\alpha}$ (also called blue-sky albedo) can then be given
as:

$$\alpha = (1 - D) \bar\alpha(\theta_i) + D \bar{\bar\alpha}.$$

This formula is important because it allows the albedo to be calculated
for any given illumination conditions from a knowledge of the intrinsic
properties of the surface.[^15]

### Changes to albedo due to human activities

![Greenhouses of Almería,
Spain]((Almería)_Greenhouses_of_Almería,_Spain_(cropped).jpg "Greenhouses of Almería, Spain")
Human activities (e.g., deforestation, farming, and urbanization) change
the albedo of various areas around the globe.[^16] [Human
impacts](Human_impact_on_the_environment "wikilink") to "the physical
properties of the land surface can perturb the climate by altering the
Earth’s radiative energy balance" even on a small scale or when
undetected by satellites.[^17]

[Urbanization](Urbanization "wikilink") generally decreases albedo
(commonly being 0.01–0.02 lower than adjacent
[croplands](croplands "wikilink")), which contributes to [global
warming](global_warming "wikilink"). Deliberately increasing albedo in
urban areas can mitigate [urban heat
island](urban_heat_island "wikilink"). An estimate in 2022 found that on
a global scale, "an albedo increase of 0.1 in worldwide urban areas
would result in a cooling effect that is equivalent to absorbing ~44
[Gt](Gigatons "wikilink") of CO2 emissions."[^18]

Intentionally enhancing the albedo of the Earth's surface, along with
its daytime [thermal emittance](thermal_emittance "wikilink"), has been
proposed as a [solar radiation
management](Solar_Radiation_Management "wikilink") strategy to mitigate
[energy crises](Energy_crisis "wikilink") and global warming known as
[passive daytime radiative
cooling](passive_daytime_radiative_cooling "wikilink")
(PDRC).[^19][^20][^21] Efforts toward widespread implementation of PDRCs
may focus on maximizing the albedo of surfaces from very low to high
values, so long as a thermal emittance of at least 90% can be
achieved.[^22]

The tens of thousands of [hectares](hectare "wikilink") of greenhouses
in [Almería, Spain](Almería,_Spain "wikilink") form a large expanse of
whitened plastic roofs. A 2008 study found that this anthropogenic
change lowered the local surface area temperature of the high-albedo
area, although changes were localized.[^23] A follow-up study found that
"CO2-eq. emissions associated to changes in surface albedo are a
consequence of land transformation" and can reduce surface temperature
increases associated with climate change.[^24]

## Examples of terrestrial albedo effects

[thumb\|upright=1.3\|The percentage of [diffusely
reflected](diffuse_reflection "wikilink")
[sunlight](sunlight "wikilink") relative to various surface
conditions](File:Albedo-e_hg.svg "wikilink")

### Illumination

Albedo is not directly dependent on the illumination because changing
the amount of incoming light proportionally changes the amount of
reflected light, except in circumstances where a change in illumination
induces a change in the Earth's surface at that location (e.g. through
melting of reflective ice). However, albedo and illumination both vary
by latitude. Albedo is highest near the poles and lowest in the
subtropics, with a local maximum in the tropics.[^25]

### Insolation effects

The intensity of albedo temperature effects depends on the amount of
albedo and the level of local [insolation](insolation "wikilink")
([solar irradiance](solar_irradiance "wikilink")); high albedo areas in
the [Arctic](Arctic "wikilink") and [Antarctic](Antarctic "wikilink")
regions are cold due to low insolation, whereas areas such as the
[Sahara Desert](Sahara_Desert "wikilink"), which also have a relatively
high albedo, will be hotter due to high insolation.
[Tropical](Tropical "wikilink") and
[sub-tropical](sub-tropical "wikilink")
[rainforest](rainforest "wikilink") areas have low albedo, and are much
hotter than their [temperate forest](temperate_forest "wikilink")
counterparts, which have lower insolation. Because insolation plays such
a big role in the heating and cooling effects of albedo, high insolation
areas like the tropics will tend to show a more pronounced fluctuation
in local temperature when local albedo changes.[^26]

Arctic regions notably release more heat back into space than what they
absorb, effectively cooling the [Earth](Earth "wikilink"). This has been
a concern since arctic ice and [snow](snow "wikilink") has been melting
at higher rates due to higher temperatures, creating regions in the
arctic that are notably darker (being water or ground which is darker
color) and reflects less heat back into space. This [feedback
loop](Ice–albedo_feedback "wikilink") results in a reduced albedo
effect.[^27]

### Climate and weather

[thumb\|right\|upright=1.5\| Some effects of global warming can either
enhance ([positive feedbacks](positive_feedback "wikilink") such as the
ice-albedo feedback) or inhibit ([negative
feedbacks](negative_feedback "wikilink"))
warming.[^28][^29]](File:20220726_Feedbacks_affecting_global_warming_and_climate_change_-_block_diagram.svg "wikilink")
Albedo affects [climate](climate "wikilink") by determining how much
[radiation](radiation "wikilink") a planet absorbs.[^30] The uneven
heating of Earth from albedo variations between land, ice, or ocean
surfaces can drive [weather](weather "wikilink").

The response of the climate system to an initial forcing is modified by
feedbacks: increased by ["self-reinforcing" or "positive"
feedbacks](Positive_feedback "wikilink") and reduced by ["balancing" or
"negative" feedbacks](Negative_feedback "wikilink").[^31] The main
reinforcing feedbacks are the [water-vapour
feedback](Water_vapour_feedback "wikilink"), the [ice–albedo
feedback](ice–albedo_feedback "wikilink"), and the net effect of
clouds.[^32]

### Albedo–temperature feedback

When an area's albedo changes due to snowfall, a snow–temperature
[feedback](feedback "wikilink") results. A layer of snowfall increases
local albedo, reflecting away sunlight, leading to local cooling. In
principle, if no outside temperature change affects this area (e.g., a
warm [air mass](air_mass "wikilink")), the raised albedo and lower
temperature would maintain the current snow and invite further snowfall,
deepening the snow–temperature feedback. However, because local
[weather](weather "wikilink") is dynamic due to the change of
[seasons](season "wikilink"), eventually warm air masses and a more
direct angle of sunlight (higher [insolation](insolation "wikilink"))
cause melting. When the melted area reveals surfaces with lower albedo,
such as grass, soil, or ocean, the effect is reversed: the darkening
surface lowers albedo, increasing local temperatures, which induces more
melting and thus reducing the albedo further, resulting in still more
heating.

### 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.[^33] Over [Antarctica](Antarctica "wikilink") 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 (the ice–albedo
[positive feedback](positive_feedback "wikilink")).

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 that this method is very expensive it has shown to work
by reducing snow and ice melt by 60%.[^34]

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](solar_radiation "wikilink") 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.[^35] Both positive feedback loops have long been
recognized as important for [global warming](global_warming "wikilink").

[Cryoconite](Cryoconite "wikilink"), powdery windblown
[dust](dust "wikilink") containing soot, sometimes reduces albedo on
glaciers and ice sheets.[^36]

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](remote_sensing "wikilink") techniques rather than applying a
single value for albedo over broad regions.

### Small-scale effects

Albedo works on a smaller scale, too. In sunlight, dark clothes absorb
more heat and light-coloured clothes reflect it better, thus allowing
some control over body temperature by exploiting the albedo effect of
the colour of external clothing.[^37]

### Solar photovoltaic effects

Albedo can affect the [electrical energy](electrical_energy "wikilink")
output of solar [photovoltaic devices](photovoltaic_system "wikilink").
For example, the effects of a spectrally responsive albedo are
illustrated by the differences between the spectrally weighted albedo of
solar photovoltaic technology based on hydrogenated amorphous silicon
(a-Si:H) and crystalline silicon (c-Si)-based compared to traditional
spectral-integrated albedo predictions. Research showed impacts of over
10% for vertically (90°) mounted systems, but such effects were
substantially lower for systems with lower surface tilts.[^38] Spectral
albedo strongly affects the performance of [bifacial solar
cells](bifacial_solar_cells "wikilink") where rear surface performance
gains of over 20% have been observed for c-Si cells installed above
healthy vegetation.[^39] An analysis on the bias due to the specular
reflectivity of 22 commonly occurring surface materials (both human-made
and natural) provided effective albedo values for simulating the
performance of seven photovoltaic materials mounted on three common
photovoltaic system topologies: industrial (solar farms), commercial
flat rooftops and residential pitched-roof applications.[^40]

### Trees

Forests generally have a low albedo because the majority of the
ultraviolet and [visible spectrum](visible_spectrum "wikilink") is
absorbed through [photosynthesis](photosynthesis "wikilink"). For this
reason, the greater heat absorption by trees could offset some of the
carbon benefits of [afforestation](afforestation "wikilink") (or offset
the negative climate impacts of
[deforestation](deforestation "wikilink")). In other words: The [climate
change mitigation](climate_change_mitigation "wikilink") effect of
[carbon sequestration](carbon_sequestration "wikilink") by forests is
partially counterbalanced in that
[reforestation](reforestation "wikilink") can decrease the reflection of
sunlight (albedo).[^41]

In the case of evergreen forests with seasonal snow cover, albedo
reduction may be significant enough for deforestation to cause a net
cooling effect.[^42] Trees also impact climate in extremely complicated
ways through [evapotranspiration](evapotranspiration "wikilink"). The
water vapor causes cooling on the land surface, causes heating where it
condenses, acts as strong greenhouse gas, and can increase albedo when
it condenses into clouds.[^43] Scientists generally treat
evapotranspiration as a net cooling impact, and the net climate impact
of albedo and evapotranspiration changes from deforestation depends
greatly on local climate.[^44]

Mid-to-high-latitude forests have a much lower albedo during snow
seasons than flat ground, thus contributing to warming. Modeling that
compares the effects of albedo differences between forests and
grasslands suggests that expanding the land area of forests in temperate
zones offers only a temporary mitigation benefit.[^45][^46][^47][^48]

In seasonally snow-covered zones, winter albedos of treeless areas are
10% to 50% higher than nearby forested areas because snow does not cover
the trees as readily. [Deciduous trees](Deciduous_trees "wikilink") have
an albedo value of about 0.15 to 0.18 whereas [coniferous
trees](coniferous_trees "wikilink") have a value of about 0.09 to
0.15.[^49] Variation in summer albedo across both forest types is
associated with maximum rates of photosynthesis because plants with high
growth capacity display a greater fraction of their foliage for direct
interception of incoming radiation in the upper canopy.[^50] The result
is that wavelengths of light not used in photosynthesis are more likely
to be reflected back to space rather than being absorbed by other
surfaces lower in the canopy.

Studies by the [Hadley Centre](Hadley_Centre "wikilink") have
investigated the relative (generally warming) effect of albedo change
and (cooling) effect of [carbon
sequestration](carbon_sequestration "wikilink") on planting forests.
They found that new forests in tropical and midlatitude areas tended to
cool; new forests in high latitudes (e.g., Siberia) were neutral or
perhaps warming.[^51]

### Water

[thumb\|upright=1.3\|Reflectivity of smooth water at (refractive
index=1.333)](File:water_reflectivity.jpg "wikilink") Water reflects
light very differently from typical terrestrial materials. The
reflectivity of a water surface is calculated using the [Fresnel
equations](Fresnel_equations "wikilink").

At the scale of the wavelength of light even wavy water is always smooth
so the light is reflected in a locally [specular
manner](specular_reflection "wikilink") (not
[diffusely](Diffuse_reflection "wikilink")). The glint of light off
water is a commonplace effect of this. At small [angles of
incident](angle_of_incidence_(optics) "wikilink") light,
[waviness](waviness "wikilink") results in reduced reflectivity because
of the steepness of the reflectivity-vs.-incident-angle curve and a
locally increased average incident angle.[^52]

Although the reflectivity of water is very low at low and medium angles
of incident light, it becomes very high at high angles of incident light
such as those that occur on the illuminated side of Earth near the
[terminator](terminator_(solar) "wikilink") (early morning, late
afternoon, and near the poles). However, as mentioned above, waviness
causes an appreciable reduction. Because light specularly reflected from
water does not usually reach the viewer, water is usually considered to
have a very low albedo in spite of its high reflectivity at high angles
of incident light.

Note that white caps on waves look white (and have high albedo) because
the water is foamed up, so there are many superimposed bubble surfaces
which reflect, adding up their reflectivities. Fresh 'black' ice
exhibits Fresnel reflection. Snow on top of this sea ice increases the
albedo to 0.9.[^53]

### Clouds

[Cloud albedo](Cloud_albedo "wikilink") has substantial influence over
atmospheric temperatures. Different types of clouds exhibit different
reflectivity, theoretically ranging in albedo from a minimum of near 0
to a maximum approaching 0.8. "On any given day, about half of Earth is
covered by clouds, which reflect more sunlight than land and water.
Clouds keep Earth cool by reflecting sunlight, but they can also serve
as blankets to trap warmth."[^54]

Albedo and climate in some areas are affected by artificial clouds, such
as those created by the [contrails](contrail "wikilink") of heavy
commercial airliner traffic.[^55] A study following the burning of the
Kuwaiti oil fields during Iraqi occupation showed that temperatures
under the burning oil fires were as much as colder than temperatures
several miles away under clear skies.[^56]

### Aerosol effects

[Aerosols](Aerosols "wikilink") (very fine particles/droplets in the
atmosphere) have both direct and indirect effects on Earth's radiative
balance. The direct (albedo) effect is generally to cool the planet; the
indirect effect (the particles act as [cloud condensation
nuclei](cloud_condensation_nuclei "wikilink") and thereby change cloud
properties) is less certain.[^57]

### Black carbon

Another albedo-related effect on the climate is from [black
carbon](black_carbon "wikilink") particles. The size of this effect is
difficult to quantify: the [Intergovernmental Panel on Climate
Change](Intergovernmental_Panel_on_Climate_Change "wikilink") estimates
that the global mean [radiative forcing](radiative_forcing "wikilink")
for black carbon aerosols from fossil fuels is +0.2 W m−2,
with a range +0.1 to +0.4 W m−2.[^58] Black carbon is a
bigger cause of the melting of the polar ice cap in the Arctic than
carbon dioxide due to its effect on the albedo.[^59]

## Astronomical albedo

[thumb\|upright=1.2\|The moon [Titan](Titan_(moon) "wikilink") is darker
than [Saturn](Saturn "wikilink") even though they receive the same
amount of sunlight. This is due to a difference in albedo (0.22 versus
0.499 in [geometric
albedo](geometric_albedo "wikilink")).In](File:Titan_and_Saturn_-_May_6_2012_-_combined_(35516187116).jpg "wikilink")
astronomy, the term **albedo** can be defined in several different ways,
depending upon the application and the wavelength of electromagnetic
radiation involved.

### Optical or visual albedo

The albedos of [planets](planet "wikilink"),
[satellites](Natural_satellite "wikilink") and [minor
planets](minor_planet "wikilink") such as
[asteroids](asteroid "wikilink") can be used to infer much about their
properties. The study of albedos, their dependence on wavelength,
lighting angle ("phase angle"), and variation in time composes a major
part of the astronomical field of
[photometry](photometry_(astronomy) "wikilink"). For small and far
objects that cannot be resolved by telescopes, much of what we know
comes from the study of their albedos. For example, the absolute albedo
can indicate the surface ice content of outer [Solar
System](Solar_System "wikilink") objects, the variation of albedo with
phase angle gives information about [regolith](regolith "wikilink")
properties, whereas unusually high radar albedo is indicative of high
metal content in [asteroids](asteroid "wikilink").

[Enceladus](Enceladus "wikilink"), a moon of Saturn, has one of the
highest known optical albedos of any body in the Solar System, with an
albedo of 0.99. Another notable high-albedo body is
[Eris](Eris_(dwarf_planet) "wikilink"), with an albedo of 0.96.[^60]
Many small objects in the outer Solar System[^61] and [asteroid
belt](asteroid_belt "wikilink") have low albedos down to about
0.05.[^62] A typical [comet nucleus](comet_nucleus "wikilink") has an
albedo of 0.04.[^63] Such a dark surface is thought to be indicative of
a primitive and heavily [space weathered](space_weathering "wikilink")
surface containing some [organic
compounds](organic_compound "wikilink").

The overall albedo of the [Moon](Moon "wikilink") is measured to be
around 0.14,[^64] but it is strongly directional and
non-[Lambertian](Lambertian_reflectance "wikilink"), displaying also a
strong [opposition effect](opposition_effect "wikilink").[^65] Although
such reflectance properties are different from those of any terrestrial
terrains, they are typical of the [regolith](regolith "wikilink")
surfaces of airless Solar System bodies.

Two common optical albedos that are used in astronomy are the (V-band)
[geometric albedo](geometric_albedo "wikilink") (measuring brightness
when illumination comes from directly behind the observer) and the [Bond
albedo](Bond_albedo "wikilink") (measuring total proportion of
electromagnetic energy reflected). Their values can differ
significantly, which is a common source of confusion.

| Planet  | Geometric   | Bond                 |
|---------|-------------|----------------------|
| Mercury | 0.142 [^66] | 0.088 [^67] or 0.068 |
| Venus   | 0.689 [^68] | 0.76 [^69] or 0.77   |
| Earth   | 0.434 [^70] | 0.306 [^71]          |
| Mars    | 0.170 [^72] | 0.250 [^73]          |
| Jupiter | 0.538 [^74] | 0.503±0.012 [^75]    |
| Saturn  | 0.499 [^76] | 0.342 [^77]          |
| Uranus  | 0.488 [^78] | 0.300 [^79]          |
| Neptune | 0.442 [^80] | 0.290 [^81]          |

In detailed studies, the directional reflectance properties of
astronomical bodies are often expressed in terms of the five [Hapke
parameters](Hapke_parameters "wikilink") which semi-empirically describe
the variation of albedo with [phase
angle](phase_angle_(astronomy) "wikilink"), including a characterization
of the opposition effect of [regolith](regolith "wikilink") surfaces.
One of these five parameters is yet another type of albedo called the
[single-scattering albedo](single-scattering_albedo "wikilink"). It is
used to define scattering of electromagnetic waves on small particles.
It depends on properties of the material ([refractive
index](refractive_index "wikilink")), the size of the particle, and the
wavelength of the incoming radiation.

An important relationship between an object's astronomical (geometric)
albedo, [absolute
magnitude](Absolute_magnitude#Absolute_magnitude_for_planets_(H) "wikilink")
and diameter is given by:[^82]
$A =\left ( \frac{1329\times10^{-H/5}}{D} \right ) ^2,$ where $A$ is the
astronomical albedo, $D$ is the diameter in kilometers, and $H$ is the
absolute magnitude.

### Radar albedo

In planetary [radar astronomy](radar_astronomy "wikilink"), a microwave
(or radar) pulse is transmitted toward a planetary target (e.g. Moon,
asteroid, etc.) and the echo from the target is measured. In most
instances, the transmitted pulse is [circularly
polarized](circular_polarization "wikilink") and the received pulse is
measured in the same sense of polarization as the transmitted pulse (SC)
and the opposite sense (OC).[^83][^84] The echo power is measured in
terms of [radar cross-section](radar_cross-section "wikilink"),
${\sigma}_{OC}$, ${\sigma}_{SC}$, or ${\sigma}_{T}$ (total power, SC +
OC) and is equal to the cross-sectional area of a metallic sphere
(perfect reflector) at the same distance as the target that would return
the same echo power.[^85]

Those components of the received echo that return from first-surface
reflections (as from a smooth or mirror-like surface) are dominated by
the OC component as there is a reversal in polarization upon reflection.
If the surface is rough at the wavelength scale or there is significant
penetration into the regolith, there will be a significant SC component
in the echo caused by multiple scattering.[^86]

For most objects in the solar system, the OC echo dominates and the most
commonly reported radar albedo parameter is the (normalized) OC radar
albedo (often shortened to radar albedo):[^87]
$\hat{\sigma}_\text{OC} = \frac{{\sigma}_\text{OC}}{\pi r^2}$

where the denominator is the effective cross-sectional area of the
target object with mean radius, $r$. A smooth metallic sphere would have
$\hat{\sigma}_\text{OC} = 1$.

#### Radar albedos of Solar System objects

| Object               | $\hat{\sigma}_\text{OC}$ |
|----------------------|--------------------------|
| Moon                 | 0.06 [^88]               |
| Mercury              | 0.05 [^89]               |
| Venus                | 0.10 [^90]               |
| Mars                 | 0.06 [^91]               |
| Avg. S-type asteroid | 0.14 [^92]               |
| Avg. C-type asteroid | 0.13 [^93]               |
| Avg. M-type asteroid | 0.26 [^94]               |
| Comet P/2005 JQ5     | 0.02 [^95]               |

The values reported for the Moon, Mercury, Mars, Venus, and Comet P/2005
JQ5 are derived from the total (OC+SC) radar albedo reported in those
references.

#### Relationship to surface [bulk density](bulk_density "wikilink")

In the event that most of the echo is from first surface reflections
($\hat{\sigma}_\text{OC} < 0.1$ or so), the OC radar albedo is a
first-order approximation of the Fresnel reflection coefficient (aka
reflectivity)[^96] and can be used to estimate the bulk density of a
planetary surface to a depth of a meter or so (a few wavelengths of the
radar wavelength which is typically at the decimeter scale) using the
following empirical relationships:[^97]

$$\rho = \begin{cases}
   3.20 \text{ g cm}^{-3} \ln \left( \frac{1 + \sqrt{0.83 \hat{\sigma}_\text{OC}}}{1 - \sqrt{0.83 \hat{\sigma}_\text{OC}}} \right) & \text{for } \hat{\sigma}_\text{OC} \le 0.07 \\
  (6.944 \hat{\sigma}_\text{OC} + 1.083) \text{ g cm}^{-3} & \text{for } \hat{\sigma}_\text{OC} > 0.07
\end{cases}$$.

## History

The term albedo was introduced into optics by [Johann Heinrich
Lambert](Johann_Heinrich_Lambert "wikilink") in his 1760 work
*[Photometria](Photometria "wikilink")*.

## See also

- [Bio-geoengineering](Bio-geoengineering "wikilink")
- [Cool roof](Cool_roof "wikilink")
- [Daisyworld](Daisyworld "wikilink")
- [Emissivity](Emissivity "wikilink")
- [Exitance](Exitance "wikilink")
- [Global dimming](Global_dimming "wikilink")
- [Ice–albedo feedback](Ice–albedo_feedback "wikilink")
- [Irradiance](Irradiance "wikilink")
- [Kirchhoff's law of thermal
  radiation](Kirchhoff's_law_of_thermal_radiation "wikilink")
- [Opposition surge](Opposition_surge "wikilink")
- [Polar see-saw](Polar_see-saw "wikilink")
- [Radar astronomy](Radar_astronomy "wikilink")
- [Solar radiation management](Solar_radiation_management "wikilink")

## References

## External links

- [Albedo Project](https://sites.google.com/site/albedoproject/home)
- [Albedo – Encyclopedia of
  Earth](http://www.eoearth.org/article/Albedo)
- [NASA MODIS BRDF/albedo product
  site](https://web.archive.org/web/20060505132944/http://www-modis.bu.edu/brdf/product.html)
- [Ocean surface albedo
  look-up-table](https://drive.google.com/drive/folders/1bVUcTBiZ1B7KhcnYeJiz-zFmpzGtrele?usp=sharing)
- [Surface albedo derived from Meteosat
  observations](https://web.archive.org/web/20081125082044/http://www.eumetsat.int/Home/Main/Access_to_Data/Meteosat_Meteorological_Products/Product_List/SP_1125489019643?l=en)
- [A discussion of Lunar
  albedos](https://web.archive.org/web/20080523151225/http://jeff.medkeff.com/astro/lunar/obs_tech/albedo.htm)
- [reflectivity of metals
  (chart)](http://www.tvu.com/metalreflectivityLR.jpg)

[Category:Land surface effects on
climate](Category:Land_surface_effects_on_climate "wikilink")
[Category:Climate change
feedbacks](Category:Climate_change_feedbacks "wikilink")
[Category:Climate forcing](Category:Climate_forcing "wikilink")
[Category:Climatology](Category:Climatology "wikilink")
[Category:Electromagnetic
radiation](Category:Electromagnetic_radiation "wikilink")
[Category:Meteorological
quantities](Category:Meteorological_quantities "wikilink")
[Category:Radiometry](Category:Radiometry "wikilink")
[Category:Scattering, absorption and radiative transfer
(optics)](Category:Scattering,_absorption_and_radiative_transfer_(optics) "wikilink")
[Category:Radiation](Category:Radiation "wikilink") [Category:1760s
neologisms](Category:1760s_neologisms "wikilink")

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[^35]: "All About Sea Ice." National Snow and Ice Data Center. Accessed
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