photosynthetic photon flux density (PPFD)


NOTE: This definition was changed in RP-16-17 Addendum 4. Deletions have a strike-through. New text is bold.

The number of photons per unit time and per unit area in the wavelength band 400 to 700 nm. Units: micromoles per second per square meter (μmol•s-1•m-2).

Note 1: There are 6.0222 x 1023 photons (Avogadro’s number) in one mole of photons.

Note 2: This unit was formerly known as microeinsteins per second per square meter.

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