Absolute refractive index

{
  "id": "MLC-T-MET-003190",
  "term": "Absolute refractive index",
  "field": "Meteorology and atmospheric science",
  "definition": "A dimensionless quantity representing the factor by which the phase velocity of electromagnetic radiation is reduced when passing through a medium compared to its speed in a vacuum. It is determined by the optical density of the material. For air at standard temperature and pressure, its value is approximately 1.00029.",
  "synonyms": [
    "absolute index of refraction"
  ],
  "see_also": [
    "refractive index"
  ],
  "url": "https://mlchart.com/terminology/meteorology/absolute-refractive-index/"
}