Base reflectivity versus composite reflectivity

"Peter R." wrote in message
oups.com...
First, a rather basic question: Why is it that all of the moisture
that appears in a composite reflectivity map is not all falling? Is
this due to the strength of the updrafts within the cell? It seems to
me that moisture that appears that heavy on radar would be heavy enough
to all fall out of the cloud.


Yes, the fact that the water is suspended high in the storm indicates that
there are strong updrafts. In a sense, the amount of water that can be
suspended aloft is a measure of the "strength" of the storm. It takes a lot
of energy to lift and suspend thousands (millions?) of tons of water miles
into the air. Once the water is dumped the storm is pretty much over. I
have flown through nasty looking CBs that showed only scattered green on
radar and there was little or no turbulence. It is diffucult to trust your
radar in such cases!


Secondly, when ATC reports specific levels of precipitation, am I to
assume that they are giving us base reflectivity? What about when FSS
gives us precipitation levels en route? Base reflectivity only?
Should we be specifically asking for composite reflectivity?


I don't know what they use or even if it is consistant. I think that they
use the scale where a level three is a thunderstorm, four is a strong
thunderstorm and five and six are considered extreme.

Mike
MU-2