Pressure maps show the expected air pressure at sea level for a day or a given time in hPa with isobars. Sometimes an indication of a high or a low pressure area is shown with H or L respectively.
The pressure can also be combined with a geopotential height. These maps show coloured areas of equal altitudes (isohypse in decametres) for a specific pressure (in general 500 hPa).
Thickness / Pressure
The thickness / pressure map shows the thickness of the air layer between 1000 and 500 hPa in metres with the help of colours according to the thickness. The mean sea level pressure is shown in hPa with isobars.