Langley (unit)

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^[1] and named after Samuel Langley (1834–1906) in 1947.

langley
Unit system	Non-SI metric unit
Unit of	Heat flux
Symbol	Ly
Named after	Samuel Langley
Derivation	1 calth/cm2
Conversions
1 Ly in ...	... is equal to ...
SI units	41 840 J/m2

Definition

One langley is

• 1 thermochemical calorie per square centimetre,^[2]
• 41 840 J/m² (joules per square metre)^[3]

See also

• Solar constant
• Radiant exposure