Garmin GPSMAP 640 Owner's Manual - Page 58

Viewing Sea Conditions, Understanding Fronts, Understanding City Forecasts

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Marine Mode: Using XM WX Weather and Audio Understanding Fronts Fronts show lines indicating the leading edge of an air mass. This feature also shows 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 relative to the surrounding area. Cold Front Warm Front Stationary Front Occluded Front Trough 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. High-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. 50 Understanding City Forecasts City forecasts appear as standard weather symbols. The forecast is viewed in 12-hour increments for the next 48 hours. City Forecasts Viewing Sea Conditions Sea Conditions provide surface conditions including winds, wave height, wave period, and wave direction. Sea Conditions GPSMAP 640 Owner's Manual

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GPSMAP 640 Owner’s Manual
Marine Mode: Using XM WX Weather and Audio
Understanding Fronts
Fronts show lines indicating the leading edge of an air mass.
This feature also shows 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 relative to the surrounding area.
Cold Front
Warm Front
Stat±onary Front
Occluded Front
Trough
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.
High-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.
Understanding City Forecasts
City forecasts appear as standard weather symbols. The forecast is
viewed in 12-hour increments for the next 48 hours.
City Forecasts
Viewing Sea Conditions
Sea Conditions provide surface conditions including winds, wave
height, wave period, and wave direction.
Sea Conditions