Storm Cell Characteristics - Honeywell IntuVue RDR-4000 Pilot's Manual

IntuVue RDR-4000 Weather Radar Pilot's Guide

STORM CELL CHARACTERISTICS

Airborne weather radar allows pilots to identify and avoid potential
weather hazards. The radar performs signal processing to estimate the
radar reflectivity of the weather ahead. Reflectivity correlates to
precipitation rate, and is displayed as green (light), yellow (moderate),
or red (heavy) precipitation.
Reflectivity helps to identify the presence of potentially hazardous
weather. However, reflectivity alone cannot determine the degree of
hazard. It is important that pilots be able to recognize hazards based on
the form of the weather (convective versus stratiform), not by observing
the reflectivity level alone.
CONVECTIVE WEATHER
Convective weather is associated with hazards due to turbulence, hail,
and lightning strike. Recognizing convective weather is instrumental in
avoiding these hazards.
Convection results in towering storm structures that can contain high
wind gradients that lead to turbulent motion. Very vigorous convection
can generate severe turbulence near the high reflectivity core,
downwind of the core, and at the top of the storm. The strength of the
convection can be judged by the vertical size of the convective cell and
the extent of high reflectivity portions of the storm.
The RDR-4000 uses these characteristics to automatically determine
the presence of turbulence. At ranges less than 40 nm (or 60 nm if the
Hazard Display features
are installed) magenta
blocks indicate areas of
particularly turbulent
activity. The radar is
capable of measuring
turbulent areas of the storm
cell at or below the green
threshold, thus it is possible
to see magenta turbulence
indications over green or
black reflectivity. Manual
mode can be used to reveal
the vertical extent of the storm. Note that moisture must be present to
detect turbulence. The radar will not detect clear air turbulence (CAT).
If the Hazard Display features are installed, hail or lightning icons will
automatically identify areas where those hazards are likely to occur.
Principles of Weather Radar Use D201002000008
38 Rev 1, December 2014