higrometry

Hypsometry, sometimes rendered as higrometry in some sources, is the measurement and analysis of the elevation distribution of the Earth's surface relative to a reference level such as mean sea level. The term hypsometry derives from Greek hypsos height and metron measure.

A primary concept is the hypsometric curve, a cumulative distribution of area as a function of elevation. On the x-axis are elevations, on the y-axis the proportion of area below that elevation. The curve's shape reflects processes such as tectonic uplift, erosion, climate, and landform development. The hypsometric integral, the area under the curve, summarizes the stage of surface evolution; higher values indicate more low-elevation relief, while lower values indicate dominance of high elevations.

Data and methods: Hypsometry uses digital elevation models (DEMs) derived from satellite remote sensing (SRTM, ASTER), LiDAR, or photogrammetry, combined with GIS to compute elevation statistics, area-elevation relationships, and hypsometric curves. Bathymetric data extend the concept underwater.

Applications include landscape evolution and tectonics assessment, climate-related erosion studies, hydrological basin analysis, watershed planning, and environmental change monitoring.

Challenges include data resolution, vertical datum consistency, and the isostatic adjustments that complicate land-sea elevation comparisons. See also hypsometry, digital elevation model, topography, bathymetry.