hectopascal (hPa)

A unit of pressure equal to 100 pascals. The pascal (Pa) is the unit of pressure in the International System (SI). A pascal is equal to the pressure exerted by a force of one newton (1 N) over a surface of one square meter (1 Pa = 1 N/m²). In that system of units, atmospheric pressure is expressed in hectopascals. One hectopascal (1 hPa) is equivalent to one millibar (1 mb). In Meteorology, pressure was traditionally expressed in millibars, but the progressive adoption of the SI has caused that unit to fall into disuse, with the hectopascal becoming standard.