On Wednesday, April 4, 2018 at 6:10:35 PM UTC-5, Duster wrote:
Assuming with his experience that he's quite aware of how thermals are generated, I'm not sure if we're addressing Mr. Guru's question about thermal diameter. Here's some references that address this issue on a more scientific basis (search "diameter" for each article if you don't want to wade thru). Aside from those factors mentioned that affect density, thermal diameter will increase with height like an expanding baloon as the relative pressure decreases. Don't forget about the effect of inertia by all that upward-moving mass. Where's our Dr. Wx?

http://trace.tennessee.edu/cgi/viewc...t=utk_gradthes

https://www.jstage.jst.go.jp/article.../54_6_427/_pdf

http://www.expandingknowledge.com/Je...Myths/Main.htm


https://rmets.onlinelibrary.wiley.co...1256/qj.03.180


I like the dedication in this (linked above) Master of Science thesis 'An Empirical Model of Thermal Updrafts Using Data Obtained From a Manned Glider":

"I would like to dedicate this thesis to my wonderful wife and children for putting up with my hectic schedule and allowing me to take the necessary time away from family time to finish this work".

I can imagine many glider pilots now willing to write a master or doctor thesis based on an empirical experience. In some cases it may take them years and years to gather the needed empirical material... :-)))