Irradiance

{
  "id": "MLC-T-CHM-013215",
  "term": "Irradiance",
  "field": "Chemistry",
  "definition": "The radiant power at any wavelength falling on a small patch of surface from the whole hemisphere above it, divided by the area of the patch. It measures the flux density arriving at a flat receiver and is expressed in watts per square metre (W m⁻²). Unlike fluence rate, which is defined for a small sphere and counts every direction equally, irradiance weights each ray by the cosine of its angle to the surface normal.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "radiant power",
    "angle",
    "fluence rate",
    "radiance",
    "spectral irradiance",
    "visible",
    "wavelength"
  ],
  "references": [
    "PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 357 (https://doi.org/10.1351/pac200779030293)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/irradiance/"
}