Oklahoma Mesonet
Oklahoma Climatological Survey: Air Masses
This Oklahoma Climatological Survey explores how air masses form, as well as the weather formations, which tend to appear on the edges of these masses in what is known as a front.
Oklahoma Mesonet
University of Oklahoma: High and Low Pressure
This University of Oklahoma meteorology tutorial explores both high and low pressure systems--how they form and the different forms they take.
University of Illinois
University of Illinois Extension: Ww2010: Atmospheric Pressure
This site from the University of Illinois describes what air pressure is and how it is measured. Explains high and low pressure areas, isobars, and how pressure changes with height.
University of Illinois
University of Illinois Urbana Champaign: Ww2010: Forces and Winds: Pressure Gradient Force
Explains what a pressure gradient is and how it produces air movement.
USA Today
Usa Today: How a Low Pressure System Affects Weather
Discusses the fronts and weather patterns associated with low pressure areas.
NASA
Nasa: How Air Pressure Affects You
This site from NASA offers a general overview of air pressure. Explores the concept through experiments and interactive games, as well as discussion questions.