Pressure varies smoothly from the Earth's surface to the top of the mesosphere. Although the pressure changes with the weather, NASA has averaged the conditions for all parts of the earth year-round. The following is a list of air pressures (as a fraction of one atmosphere) with the corresponding average altitudes. The table gives a rough idea of air pressure at various altitudes. Subscript textInsert non-formatted text here== Calculating variation with altitude == See also: Barometric formula Equation 1: Equation 2: where Or converted to Imperial units: where