This is an audio version of the Chapter 15 titled "Earth's Atmosphere", Section 4 "Air Movement" in the CK12 Earth Science for Middle School Book by Authors Jean Brainard Ph.D. and Julie Sandeen created and used under the Creative Common Attribution/Non-Commercial/Share Alike 3.0 Unported (CC-by_NC-SA) License (http://creativecommons.org/licenses/by-nc-sa/3.0/). Don't forget to say thanks at http://www.ck-12.org/saythanks/
