An '''Air mass''' is large body of [[air]], often hundreds or thousands of [[mile]]s across, containing air of a similar [[temperature]] and [[humidity]]. Sometimes the differences between air masses are hardly noticeable, but if colliding air masses have very different temperatures and humidity values, [[storm]]s can erupt.<ref>http://eobglossary.gsfc.nasa.gov/Library/glossary.php3?mode=all</ref>
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A large body of [[air]] with relatively uniform [[pressure]], [[temperature]], and [[humidity]].<ref>Wile, Dr. Jay L. ''Exploring Creation With Physical Science''. Apologia Educational Ministries, Inc. 1999, 2000</ref>