I`ll go back to my reference to Dennis Pagen, who wrote "Understanding the sky", wherein he explains how thermals are formed, which is kinda important to free-flying people, and therefore relevant in this thread.
I won`t get into it in detail, suffice to say that thermals are really just a whole lot of hot air.
Which brings me to my point : If this thread was on a paragliding forum, we`d all be at cloudbase by now.