Searchlight

{
  "id": "MLC-T-MET-008724",
  "term": "Searchlight",
  "field": "Meteorology and atmospheric science",
  "definition": "An instrument used in early methods of determining cloud base height at night, consisting of a powerful light source that projects a narrow, vertical beam onto the underside of a cloud layer. An observer at a known horizontal distance from the searchlight measures the elevation angle of the illuminated spot on the cloud base using a clinometer. The height of the cloud base is then calculated using simple trigonometry, as the product of the baseline distance and the tangent of the measured elevation angle.",
  "url": "https://mlchart.com/terminology/meteorology/searchlight/"
}