[FRIAM] Manifold Clarification

[Steve Smith]

> I said that no physical object is a manifold.  This may be a better
> answer to Nick's question.  The envelope of a cloud, if it could be
> defined, might be a manifold depending on cusps etc.  Those might be
> handled by combining manifolds of different dimensions.  This would
> not be a realizable project in my opinion.
>
> Frank

More likely darn near a fractal surface... down to the size of a
condensed droplet of water?  Ken Perlin's cloud-modeling comes to mind
(multi-scale if not literally fractal).

But model(ed/able) as an idealized manifold based on the triple-point of
water (or is that only clouds forming hail or sleet?) 

Nick? mentioned "shroud" which I don't think has a mathematical
definition but i took it to mean something like a convex-hull
(shrink-wrapped surface).  From work with Stephen on using imagery of
clouds (or plumes) to calibrate cameras and to estimate their shape as a
function of time, we have looked at things like silhouette analysis.  

Clouds and plumes are not entirely opaque and I believe that is because
they are "porous'...   I'm not sure if there are examples in nature of
fully saturated water vapor...  maybe only in a vacuum?   Clouds are
(I'm pretty sure) condensed droplets of water vapor dispersed among air
molecules (I suppose I could read up  more on cloud science).  Plumes
(smoke from a wildfire) are a little more complex but have a significant
component of water vapor/droplets as well as hydrocarbon particulates? 
Guerin is surely much more up on this.   During the 2011 Cerro Grande
Fire, we had *baked* pine needles settling around our property... they
were not burned, but may have been fully charred (all volatiles
pyrolized), probably in such an oxygen poor environment that they
couldn't burn.   This was probably a "sorting" process... smaller bits
may have traveled further while larger ones (twigs and branches) fell
short(er)...  

- Steve