Critical level of escape

{
  "id": "MLC-T-MET-004763",
  "term": "Critical level of escape",
  "field": "Meteorology and atmospheric science",
  "definition": "The altitude in a planetary atmosphere where the mean free path of an atmospheric constituent becomes comparable to the scale height, allowing particles to escape into space. Above this level, collisions are infrequent enough that particles moving upwards with sufficient velocity can overcome gravity. For Earth's atmosphere, this level is typically in the exosphere, around 500-1000 km.",
  "synonyms": [
    "exobase",
    "critical level"
  ],
  "see_also": [
    "cone of escape",
    "fringe region"
  ],
  "url": "https://mlchart.com/terminology/meteorology/critical-level-of-escape/"
}