I'm reading a really old paper which looks at estimating the surface energy fluxes for The Great Lakes. They show all of their values as Langleys per day. Can this be converted to Watts per meter squared? Also, what is a Langley?


The unit langley is amount of energy distributed over an area found in solar radiation, named after Samuel Pierpont Langley. The conversion is straight-forward:

$$ 1\frac{\rm ly}{\rm min}=697.3\,\frac{\rm W}{\rm m^2} $$

So you'll have to do some more unit conversions to get the ly/day to W/m$^2$ conversion.

See also this site for other unit conversions common in solar radiation.

  • 1
    $\begingroup$ So, basically if I have a value in Langley per day and wanted W/m2, I would first divide my value by 1440 (to get langley per min) and then multiply by 697.3 to get W/m2? $\endgroup$ – Emma Tebbs Jun 11 '15 at 20:43
  • $\begingroup$ That's correct. $\endgroup$ – Kyle Kanos Jun 11 '15 at 20:46

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