A standard atmosphere, abbreviated atm, is the unit of pressure equal to the average atmospheric pressure at sea level. Specifically 1 atm = 101,325 pascals, which is the SI unit of pressure. When scientists refer to STP (standard temperature and pressure), this refers to a set of conditions for a system, one of which is a pressure of 1 atm.
This is an important unit for describing gasses, as pressure is one of the state variables that describe the gas in a heat engine.
To read more about the atm, click here.
For further reading
- ↑ R. Serway and J. Jewett, "Pressure," in Physics for Scientists and Engineers, 8th ed., Belmont, CA: Cengage Learning, 2010, ch.14, sec.1, pp. 405