Langley (unit)
{{refimprove|date=August 2010}}
{{Infobox unit
| bgcolor =
| name = langley
| image =
| caption =
| standard = Non-SI metric unit
| quantity = Heat flux
| symbol = Ly
| namedafter = Samuel Langley
| extralabel = Derivation
| extradata = 1 calth/cm2
| units1 = SI units
| inunits1 = 41 840 J/m2
}}
The langley (Ly) is a unit of heat transmission, especially used to express the rate of solar radiation (or insolation) received by the earth. The unit was proposed by Franz Linke in 1942{{cite encyclopedia|last=Gyllenbok|first=Jan|author-link=Jan Gyllenbok|editor-last=|editor-first=|editor-link=|encyclopedia=Encyclopaedia of Historical Metrology, Weights, and Measures, Volume 1|title=langley|language=|edition=|year=2018|publisher=Birkhäuser|series=|location=|id=|isbn=9783319575988|oclc=|doi=|page=139|quote=}} and named after Samuel Langley (1834–1906) in 1947.
Definition
One langley is
- 1 thermochemical calorie per square centimetre,{{Cite web|authorlink=A. Thompson and B. N. Taylor|title=Appendix B9. Conversion Factors.|work=NIST Guide to the SI|publisher=The National Institute of Standards and Technology|date=2010-10-05|url=http://physics.nist.gov/Pubs/SP811/appenB9.html|accessdate=2013-04-14}}
- 41 840 J/m2 (joules per square metre){{cite web|url=http://www.racerocks.com/racerock/abiotic/solar/solar.htm|title=Solar Energy at Race Rocks|access-date=2010-08-05|archive-url=https://web.archive.org/web/20131005002713/http://www.racerocks.com/racerock/abiotic/solar/solar.htm|archive-date=2013-10-05|url-status=dead}}