Optical air mass

{
  "id": "MLC-T-MET-007704",
  "term": "Optical air mass",
  "field": "Meteorology and atmospheric science",
  "definition": "The relative path length of sunlight through the Earth's atmosphere, normalized to the path length when the sun is directly overhead (at the zenith). It quantifies the amount of atmosphere that solar radiation must traverse, influencing the attenuation of solar energy. At sea level, the optical air mass is approximately 1.0 at zenith and increases as the sun approaches the horizon.",
  "url": "https://mlchart.com/terminology/meteorology/optical-air-mass/"
}