Garmin G500 Pilots Guide - Page 166

Link Page. For the NEXRAD legend, select the LEGEND soft key when NEXRAD is selected for display. Foreword System Sec 1 PFD Sec 2 MFD Sec 3 Features Avoidance Hazard Sec 4 Additional Sec 5 & Alerts Annun. Sec 6 Symbols Sec 7 Figure 4-24 NEXRAD Weather Legend The display of radar coverage is always active when either NEXRAD or ECHO TOPS is selected. Areas where NEXRAD radar coverage and Echo Tops information is not currently available or is not being collected are indicated in grayish-purple. 4.7.5.1 Reflectivity Reflectivity is the amount of transmitted power returned to the radar receiver. Colors on the NEXRAD display directly correlate to the level of detected reflectivity. Reflectivity as it relates to hazardous weather can be very complex. The role of radar is essentially to detect moisture in the atmosphere. Simply put, certain types of weather reflect radar better than others. The intensity of a radar reflection is not necessarily an indication of the weather hazard level. For instance, wet hail returns a strong radar reflection, while dry hail does not. Both wet and dry hail can be extremely hazardous. The different NEXRAD echo intensities are measured in decibels (dB) relative to reflectivity (Z). NEXRAD measures the radar reflectivity ratio, or the energy reflected back to the radar receiver (designated by the letter Z). The value of Z increases as the returned signal strength increases. 4-38 Garmin G500 Pilot's Guide 190-01102-02 Rev. B Appendix A Glossary Sec 8 Index Appendix B