Its SI unit is newtons per square metre or pascals. This result is in the S.I. unit Pascals, equivalent to N/m (newtons per square meter). For comparison, 1 atmosphere is 101,325 Pascals or 14.7 PSI. The pressure gradient is a dimensional quantity expressed in units of pascals per metre (Pa/m). It experiences atmospheric pressure lower than 107 pascals at the summit. This is and has units of pascals per second. And at other locations destructive interference occurs, causing a local sound pressure of zero pascals. In practically all other fields, the kilopascal (1000 pascals) is used instead. SI units for "P" are pascals (Pa), while "t" and "d"=2"r" are in meters (m).