Mike,

MP>Is a scud cloud the same as a wall cloud?  Or is it just one with a
MP>downward-pointing, non-rotating mass?

  No. Here are the definitions from the National Weather Service
Weather Glossary for both:

***

Scud
Small, ragged, low cloud fragments that are unattached to a larger
cloud base and often seen with and behind cold fronts and thunderstorm
gust fronts. Such clouds generally are associated with cool moist air,
such as thunderstorm outflow.

***

Wall Cloud
A localized, persistent, often abrupt lowering from a rain-free base.
Wall clouds can range from a fraction of a mile up to nearly five miles
in diameter, and normally are found on the south or southwest (inflow)
side of the thunderstorm. When seen from within several miles, many wall
clouds exhibit rapid upward motion and cyclonic rotation.

However, not all wall clouds rotate. Rotating wall clouds usually develop
before strong or violent tornadoes, by anywhere from a few minutes up to
nearly an hour. Wall clouds should be monitored visually for signs of
persistent, sustained rotation and/or rapid vertical motion.

"Wall cloud" also is used occasionally in tropical meteorology to
describe the inner cloud wall surrounding the eye of a tropical cyclone,
but the proper term for this feature is eyewall.

***

MP>I have seen the latter... they often seem to accompany non-severe,
MP>sometimes cooler weather around here.

  Sometimes, you get cold air funnels...here is the definition for that
one:

Cold Air Funnel
A funnel cloud or (rarely) a small, relatively weak tornado that can
develop from a small shower or thunderstorm when the air aloft is
unusually cold (hence the name). They are much less violent than other
types of tornadoes.

  And, that's Meteorology 101 for today. 

Daryl

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