Garmin Pilot User's Guide for iOS User Manual page 82

Plan
Composite data from radar sites in the United States is shown. This data is
composed of the maximum reflectivity from the individual radar sweeps at different tilt
angles of the radar beam with respect to the ground. The display of the information
is color-coded to indicate the weather severity level. Colors are used to identify the
different echo intensities (reflectivity) measured in dBZ (decibels or Z). "Reflectivity"
(designated by the letter Z) is the amount of transmitted power returned to the radar
receiver. The dBZ values increase as returned signal strength increases. Precipitation
intensity is displayed using colors corresponding to the dBZ values.
RADAR ABNORMALITIES
There are possible abnormalities regarding displayed radar images. Some, but not
all, of those include:
• Ground clutter
• Strobes and spurious radar data
• Sun strobes (when the radar antenna points directly at the sun)
• Military aircraft deploy metallic dust (chaff) which can cause alterations in radar
scans
• Interference from buildings or mountains, which may cause shadows
RADAR LIMITATIONS
Certain limitations exist regarding radar displays. Some, but not all, are listed for
the user's awareness:
• Surface precipitation type is estimated with shades of blue for snow and shades
of pink for indeterminate types. The actual precipitation type aloft could vary.
• Radar base reflectivity is sampled at the minimum antenna elevation angle. An
individual radar site cannot depict high altitude storms at close ranges, and has
no information about storms directly over the site.
• Radar coverage in Canada is only available in the southern 1/4 of the country.
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Garmin Pilot for iOS User's Guide 190-01501-00 Rev. D