A unit of measurement for illuminance, indicating the amount of light falling on a surface; not as precise for plants as PPFD because lux is a unit of measurement that quantifies illuminance, which is the amount of visible light (including all wavelengths) that falls on a surface. Lux is calibrated to the sensitivity of the human eye and how humans perceive light, rather than being tailored to the specific light wavelengths that plants use for photosynthesis and other physiological processes.

See Also