Speed-up height

{
  "id": "MLC-T-MET-009125",
  "term": "Speed-up height",
  "field": "Meteorology and atmospheric science",
  "definition": "The height above the ground, usually taken at a hill crest, at which the fractional speed-up of the wind reaches its maximum. In linear theory of boundary-layer flow over low hills it lies within the shallow inner layer near the surface, below which friction slows the air, and above which the speed-up decays toward the undisturbed upstream wind. Its value scales with the inner-layer depth, which grows with the hill's horizontal length and with surface roughness.",
  "url": "https://mlchart.com/terminology/meteorology/speed-up-height/"
}