Cup crystal

{
  "id": "MLC-T-MET-004803",
  "term": "Cup crystal",
  "field": "Meteorology and atmospheric science",
  "definition": "A large faceted ice grain shaped like a hollow hexagonal cup, the typical crystal of depth hoar in a snowpack. It grows when water vapor rises through the snow under a steep temperature gradient and deposits on existing grains, mostly near the ground. The grains, up to about 10 millimeters across, bond poorly and form weak layers that raise avalanche risk.",
  "url": "https://mlchart.com/terminology/meteorology/cup-crystal/"
}