http://kids.earth.nasa.gov/archive/air_pressure/index.html

http://en.wikipedia.org/wiki/Atmospheric_pressure

http://www.srh.noaa.gov/jetstream/atmos/pressure.htm

http://userpages.umbc.edu/~tokay/chapter5.html

http://www.usatoday.com/weather/wbarocx.htm

http://www.rcn27.dial.pipex.com/cloudsrus/pressure.html

http://www.uwlax.edu/faculty/skala/Air-Pressure.htm

http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/circulation/air_pressure_p_1.html

http://www.grc.nasa.gov/WWW/K-12/airplane/pressure.html

http://www.bom.gov.au/lam/Students_Teachers/pressure.shtml