OK questions ....
1) why is there this inverse relationship between the two ?
2) could "vertical windshear" be clarified and could I identify its presence visually during the cell growth ?
3) several times on various forums I have seen the term "CIN" used what is that ? haven't found reference
to it in any of the glossaries I have looked through.
thanks
Dave N 
Hi Dave,
my several cents worth:
(1) My use of 'inverse relationship' is probably a bit misleading - 'compensatory effects' might have been a better way to put it.
Scatter plots (CAPE v Windshear') of past events have revealed the relationship between these parameters that I mentioned (an example attached). The reasoning behind this, in fairly simple terms is:
Higher values of CAPE (or, let's say a lower lifted index (more negative)) would promote a stonger updraft resulting in more vertical stretching (the ballerina analogy is useful to think of here), hence leading to more rotation on the storm scale for a given amount of ambient vertical wind shear.
At the other end of the spectrum, when the surface through to 6km windshear exceeds approximately 50 knots, an updraft will tend to rotate as a result of horizontal vorticity being tilted into the vertical. A product of this mid-level rotation is the development of a pressure pertubation gradient, a dynamic effect that increases with the amount of rotation (I discussed this over on TWZ in the thread on storms in the top-end and extratropics). This is a kind of feedback mechanism whereby the strengthening updraft lowers the pressure in the mid-levels which in turn further strengthens the updraft - this dynamic effects is equally as important , if not more important than buoyancy alone if determining updraft strength and rotation.
(2) Windshear refers to a change in winds (speed and / or direction) with height. It is revealed when clouds at different altitudes are seen to be moving in different directions. With respect to cell growth, vertical windshear might be revealed as towers which 'lean' downshear.
(3) CIN = Convective Inhibition. On a skew-T plot, CAPE reflects positive buoyancy, CIN reflects negative buoyancy (anyone feel free to post a skew-t here to illustrate this!)
