BendixKing IN-862A System RDR-2100 - Manual (Page 15)

Effective Date: 9/98 RDR 2100 Pilot's Guide: Rev 1
11
Theory of Operation
RADAR REFLECTIVITY
What target will reflect the radar’s pulses and thus be displayed on the
indicator? Only precipitation (or objects more dense than water such as
earth or solid structures) will be detected by an X-band weather radar.
Therefore weather radar does not detect clouds, thunderstorms or turbu-
lence directly. Instead, it detects precipitation which may be associated
with dangerous thunderstorms and turbulence. The best radar reflectors
are raindrops and wet snow or hail. The larger the raindrop the better it
reflects. Because large drops in a small concentrated area are charac-
teristic of a severe thunderstorm, the radar displays the storm as a
strong echo. Drop size is the most important factor in high radar reflec-
tivity. Generally, ice, dry snow, and dry hail have low reflective levels
and often will not be displayed by the radar.
A cloud that contains only small raindrops, such as fog or drizzle, will not
produce a measurable radar echo. But if the conditions should change
and the cloud begins to produce rain, it will be displayed on radar.
RDR 2100 PG 3/12/07 3:45 PM Page 11