Garmin G2000 Pilots Guide - Page 394

Hazard Avoidance SYSTEM OVERVIEW FLIGHT INSTRUMENTS EIS AVOIDANCE MANAGEMENT AUDIO & CNS FLIGHT HAZARD AFCS Figure 6-56 Garmin Connext Radar Legend The display of no radar coverage is enabled when Precipitation is selected for display. Areas where precipitation radar coverage is not currently available or is not being collected are indicated in gray shade of purple. A white boundary line with white tick marks depicts the selected coverage area of the weather data request (as defined as the Data Request window). This boundary encloses the precipitation data when this weather product is displayed. Reflectivity Reflectivity is the amount of transmitted power returned to the radar receiver. Colors on the Precipitation 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 radar echo intensities are measured in decibels (dB) relative to reflectivity (Z). Weather radars measure the 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. Radar Limitations Radar images may have certain limitations: • Radar base reflectivity does not provide sufficient information to determine cloud layers or precipitation characteristics (wet hail vs. rain). For example, it is not possible to distinguish between wet snow, wet hail, and rain. • Radar base reflectivity is sampled at the minimum antenna elevation angle. An individual radar 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. 380 Garmin G2000 Pilot's Guide for the Cessna T240 190-01263-01 Rev. A ADDITIONAL FEATURES APPENDICES INDEX