Garmin GDL 30A - Manual (Page 17)

GDL 30A Owner’s Manual 
Fronts
The Fronts feature displays the lines indicating the leading edge of an air mass that is replacing an existing air mass. This feature also displays
pressure centers. Pressure centers are represented by a large red “L” for low-pressure centers or a large blue “H” for high-pressure centers.
Pressure centers represent an area where pressure is measured to be either the highest or the lowest pressure relative to the surrounding area.
Cold Front
Warm Front
Stationary
Front
Occluded
Front
Dry Line
Indicates a high-pressure center. Similar to a low-
pressure center, a high-pressure center is an area
where the measured pressure is highest relative to the
surrounding area. Moving away from a high-pressure
center in any horizontal direction results in decreased
pressure. Winds flow clockwise around high-pressure
centers in North America.
Indicates a low-pressure center. A low-pressure center
is an area where the measured pressure is lowest
relative to the surrounding area. Moving away from a
low-pressure center in any horizontal direction results
in increased pressure. Winds flow counterclockwise
around low-pressure centers in North America.
XM WX Weather Features