Atmospheric stability and lapse rate

Lapse rate can also tell you what type of icing you are likely to get.
Unstable clouds are more likely to have clear ice (the bad kind), and
stable clouds are likely to be rime ice.



"Icebound" wrote in
:


"Corky Scott" wrote in message
news
On Wed, 9 Feb 2005 18:29:52 -0500, "Icebound"
wrote:

If a pilot does not know the definition of lapse rate, then it is
pretty difficult for him to recognize the conditions which lead to
atmospheric buoyancy or to atmospheric stability.

You really think so? You feel that people would not/do not
understand how and when clouds might form if they do not have an
understanding of what lapse rate is?

Well, no, pretty much by definition they would not.

Many sunny days clouds form. Many other sunny days they do not.
Should we just be *surprised* by the formation of cloud on this day,
or *surprised* by the absence of cloud on another?

If you know that on sunny days clouds form because bubbles of air move
upward and cool to the point of condensation, you already know
something about environmental and adiabatic lapse rates, even if you
will not admit it. Otherwise, why would you expect clouds to form
even if these bubbles do float upward?


When I flew out to Oshkosh in '95 in the front seat of a Waco UPF-7,
we encountered a LOT of thunderstorms along our route. The plan was
to fly from Vermont due west staying south of the Great Lakes until
we reached Chicago, then turn right. Known as the "Northeast
Corridor" it's home to a lot of thunderstorm activity during the
summer. Typically, we'd fly along our route for as long as possible,
and when the sky filled with thunderstorms that we could no longer
fly around, we landed and waited them out. We ended up waiting more
than we'd planned due to the amount of storms we encountered. By the
time we turned north past Chicago, the storms were individually
extremely violent but isolated and we could and did just detour
around them.

How would the pilot who truly understood lapse rate have flown it any
differently?


You asked for a practical situation and I gave you one.

Maybe he would fly your situation no differently at all... As I said
before, lots of situations when the pilot will not have sufficient
information beyond what he sees out the window.

But he *would* be flying with the subtle difference that he is
pressing on because he understands what is happening here and can
*anticipate any changes*, rather than just *react to changes*. And
he would also be more comfortable *in advance* about the probability
of his success-without-diversion.