Weather Radar is the same as vision in another part of the spectrum. It has
certain resolution and can penetrate a certain distance into obscuring
conditions. The beam reflects off all surfaces (except the stuff stealth
aircraft are made of presumably). The value of radar is that there is a
very high corralation between the reflectivity of water droplets and
turbulence. Large droplets are formed from vertical motion.and large
droplets reflect radar much better than small ones (that is why most clouds
appear transparent to radar.). More vertical motion larger drops. You have
undoubtedly experienced the difference in drop sizes from thunderstorms vs.
stratiform rain. To evaluate a target, you first have to determine that you
are not looking at a ground return which you do by knowing your altitude,
beam width and antenna tilt setting. Generally you avoid all radar targets
containing red (40dbz) returns. You avoid the whole target, not just the
red part. I usually avoid yellow too. Even green targets are fairly bumpy
and full of ice at cruise altitudes (above FL180). Green at lower altiudes
can be smooth. There are various shapes that are associated with hail and
tornados but most people avoid all thunderstorms. The irregular targets are
just avoided by a greater distance.

Basically it comes down to the fact that anything that lifts huge amounts of
water miles into the atmosphere contains a lot of vertical shear and
therefore turbulence.

There are several books on the subject, I like Archie Trammels stuff, Dave
Gwinn's book and Severe Weather Flying by Newton. There was a great deal on
AvWeb a couple of years ago where you got Trammels video course, Severe
Weather Flying and Buck's Weather Flying for around $125 along with a
discount for his live course.

Mike
MU-2


"Matt Young" wrote in message
ink.net...
A question about something that I guess I just didn't get enough info on
during my instrument training. What exactly are you looking for when
looking at a radar image. Are you trying to avoid all returns? Is an area
of just green ok? Any other things in particular to look for?