Changes

The average time a given molecule of water will stay in a given water source.<ref>Wile, Dr. Jay L. ''Exploring Creation With Physical Science''. Apologia Educational Ministries, Inc. 1999, 2000</ref>

'''Residence time''' is the average time that a [[molecule]] of a substance stays in a given area. Residence time of species X is defined as the ratio of the mass X in the area to its removal rate.<ref name="jacob">Jacob, Daniel J. ''Introduction to Atmospheric Chemistry'' Princeton University: 1999</ref>

 

In [[atmospheric chemistry]], residence time is also called ''lifetime''. It can be used to describe how long [[pollutant]]s stay in the atmosphere. <ref name="jacob" />

==References==

==References==