Garmin G500 Pilots Guide - Page 167

NEXRAD Limitations

Page 167 highlights

Foreword Sec 1 System Sec 2 PFD 4.7.5.2 NEXRAD Limitations NEXRAD radar images may have certain limitations: • NEXRAD base reflectivity does not provide sufficient information to determine cloud layers or precipitation characteristics. For example, it is not possible to distinguish between wet snow, wet hail, and rain. • NEXRAD base reflectivity is sampled at the minimum antenna elevation angle. An individual NEXRAD site cannot depict high altitude storms at close ranges. It has no information about storms directly over the site. • When zoomed in to a range of 30 NM, each square block on the display represents an area of four square kilometers. The intensity level reflected by each square represents the highest level of NEXRAD data sampled within the area. The following may cause abnormalities in displayed NEXRAD radar images: • Ground clutter • Strobes and spurious radar data • Sun strobes (when the radar antenna points directly at the sun) • Interference from buildings or mountains, which may cause shadows • Metallic dust from military aircraft, which can cause alterations in radar scans Sec 3 MFD Sec 4 Hazard Avoidance Features Sec 5 Additional Sec 6 Annun. & Alerts Sec 7 Symbols Sec 8 Glossary Appendix A Appendix B Index 190-01102-02 Rev. B Garmin G500 Pilot's Guide 4-39

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4-39
190-01102-02
Rev. B
Garmin G500 Pilot’s Guide
Foreword
Sec 1
System
Sec 2
PFD
Sec 3
MFD
Sec 4
Hazard
Avoidance
Sec 5
Additional
Features
Sec 6
Annun.
& Alerts
Sec 7
Symbols
Sec 8
Glossary
Appendix A
Appendix B
Index
4.7.5.2
NEXRAD Limitations
NEXRAD radar images may have certain limitations:
• NEXRAD base reflectivity
does not provide sufficient information to
determine cloud layers or precipitation characteristics. For example, it is
not possible to distinguish between wet snow, wet hail, and rain.
• NEXRAD base reflectivity is sampled at the minimum antenna elevation
angle. An individual NEXRAD site cannot depict high altitude storms at
close ranges. It has no information about storms directly over the site.
• When zoomed in to a range of 30 NM, each square block on the display
represents an area of four square kilometers. The intensity level reflected
by each square represents the highest level of NEXRAD data sampled
within the area.
The following may cause abnormalities in displayed NEXRAD radar images:
• Ground clutter
• Strobes and spurious radar data
• Sun strobes (when the radar antenna points directly at the sun)
• Interference from buildings or mountains, which may cause shadows
• Metallic dust from military
aircraft, which can cause alterations in radar
scans