Standardtrykket

Standardtrykket, or standard pressure, is a reference pressure used across fields such as meteorology, chemistry, and physics. It denotes a fixed pressure value chosen to serve as a baseline for measurements, calculations, and comparisons.

In meteorology, standard pressure usually refers to mean sea-level pressure, commonly set at 1013.25 hectopascals (hPa). This value is equivalent to 1013.25 millibars and 101.325 kilopascals (kPa). It provides a baseline for weather charts, forecasts, and for adjusting observed pressures to sea level to compare conditions across different locations and times. Real atmospheric pressure varies with altitude and weather systems.

In chemistry and thermodynamics, standard pressure is a reference condition used in standard state definitions. The most widely adopted modern convention is 1 bar (exactly 100 kPa). Historically, 1 atmosphere (1 atm ≈ 101.325 kPa) was used as the standard pressure in many contexts. Some older literature and certain applications still refer to atm as the standard pressure, but 1 bar is now the common standard in many international guidelines.

Units and conversions commonly encountered include hPa, Pa, kPa, bar, and atm. While 1013.25 hPa is tied to meteorology, 1 bar is the standard reference in thermodynamics, with 1 atm still appearing in legacy documents and some practical settings. Understanding the context is essential, as the term can denote different fixed values depending on the discipline.