Forbidden transitions

{
  "id": "MLC-T-MET-005703",
  "term": "Forbidden transitions",
  "field": "Meteorology and atmospheric science",
  "definition": "Quantum mechanical transitions between energy levels in atoms or molecules that are highly improbable according to selection rules, but can still occur under specific conditions. In atmospheric science, these transitions are relevant for understanding the emission and absorption of radiation by trace gases, particularly in the upper atmosphere where collision rates are low. They often have very long lifetimes compared to allowed transitions.",
  "url": "https://mlchart.com/terminology/meteorology/forbidden-transitions/"
}