Constant pressure charts like the 500 mb chart shown below may seem obvious to interpret. It has many features similar to ...

because those giant H’s and L’s representing high and low air pressure systems on a weather map are meaningless without understanding their significance. HELP FROM HIGH PRESSURE: How Houston's ...

High pressure often represents stable air, while low pressure can signify instability. On a cold, sunny day there will be a significantly higher atmospheric pressure than when a big storm is ...

Pressure is measured in millibars. Standard pressure at sea level is 1013 millibars, but large areas of either high or low pressure can occur. Areas of high and low pressure are caused by rising ...