Figure: Stratus rain, from Honeywell Radar Training Course, Part 2, Slide 11.
Stratus Rain is normally no higher than 15,000 feet and can spread for hundreds of miles; it is not particularly dangerous.
Airborne radar cannot differentiate between light rain and the ground when at high altitude looking down. The reflectivity of the ground, especially if it is wet, greatly exceeds the water droplets. Once the aircraft has descended and is looking up at the rain, the problem goes away.
Figure: Stratus rain summary, from Honeywell Radar Training Course, Part 6, Slide 7.
Figure: Thunderstorm, from Honeywell Radar Training Course, Part 2, Slide 9.
The highest concentration of rain and rain-covered hail is in what meteorologists call the "bright band," typically located between 8,000 and 17,000 feet. This area offers the highest reflectivity, where the most information to radar is available. The beam must be pointed into this area to properly evaluate the storm's danger.
Figure: Super-cell thunderstorm, from Honeywell Radar Training Course, Part 2, Slide 10.
A Super-Cell Thunderstorm is much wider than an ordinary thunderstorm and can often be identified by the radar shadow it creates. (The green arc above is ground clutter, but this ground clutter doesn't show behind the super-cell thunderstorm which obscures all radar returns from behind.)
Radar Example of Stratus Rain, Ordinary Thunderstorms, and Super-Cells
Figure: Example weather targets, from Honeywell Radar Training Course, Part 2, Slide 12.
Radar Example of a Blind Alley
Figure: Blind alley, from Honeywell Radar Training Course, Part 2, Slide 15.
Radar Example of a Thunderstorm Downwind
Figure: Upwind deviation, from Honeywell Radar Training Course, Part 2, Slide 16.
Whenever possible, deviate to the upwind side since a thunderstorm can create downwind eddy currents (turbulence).
An Example: 1 Jun 2011 over KBED
The Radar Shot
Photo: From Eddie's cockpit.
The Window Shots
Photos: Views from the right seat, from Eddie's cockpit.
Just a few to ponder:
More About Radar
Portions of this page can be found in the book Flight Lessons 1: Basic Flight, Chapter 28.
Honeywell Airborne Weather Radar Training, Rev E, 12/09/02, Honeywell Inc. Commercial Flight Systems Group, Phoenix, AZ.
Honeywell Primus 880 Pilot's Guide, Pub. No. A28-1146-102-03, Revised January 2006, Honeywell International Inc. Commercial Electronic Systems, Glendale, AZ.