The pascal is the SI unit used to measure atmospheric pressure.
One pascal equals one newton per square metre. The unit is named after Blaise Pascal, the French mathematician and physicist whose work included important studies of fluids and pressure. Because atmospheric pressure is large compared with one pascal, meteorologists commonly use the hectopascal, equal to 100 pascals.
Weather maps often report sea-level pressure in hectopascals, abbreviated hPa. Standard atmospheric pressure is 1013.25 hPa, equivalent to 101,325 pascals. The millibar has the same numerical value as the hectopascal, so weather reports may use either term. Pascal is a pressure unit; kelvin measures temperature, while newton measures force.