Michelson actinometer

{
  "id": "MLC-T-MET-007271",
  "term": "Michelson actinometer",
  "field": "Meteorology and atmospheric science",
  "definition": "A portable pyrheliometer in which sunlight falls on a blackened bimetallic strip whose bending, read against a scale, indicates the intensity of direct solar radiation. It needs calibration against a standard instrument, because the deflection is not an absolute measure. It records the beam reaching the ground, not the solar constant, which has to be inferred by extrapolating such readings to the top of the atmosphere.",
  "url": "https://mlchart.com/terminology/meteorology/michelson-actinometer/"
}