Chris
What I have learnt in twenty years of gliding and paragliding is that the atmosphere is made up of homogeneous "packets" that don't mix and that the boundary layers are the source of turbulence.
There is also a channeling effect - a bit like ducting with VHF.
I was very lucky a few years ago with a setting sun on my local mountain when the sea breeze wind started to increase.
I didn't understand it at the time but had enough of flying and decided to spiral down to top land near my Jag only to find myself flying backwards...
After survival mode kicked in I passed three landing options going backwards to land vertically in a blackberry bush and a 25ft pine tree at the edge of a plantation saved me getting seriously hurt.
It took the best part of an hour to extract my paraglider and another hour to retrieve the motor which gave me enough time to figure out the cause.
Which was the inversion was acting as a Venturi with the ground as the other wall.Whilst the sea breeze was decreasing the Venturi effect and the mountain were forming a choke.
I only did the Andes once on the Death Ship...a turn around ex Rio to Santiago..and with light winds it wasn't a problem and I had never heard of Bcals tropopause theory but it makes sense with the wave system bouncing off the layer.
What still surprises me is the lack of communication between disciplines (and companies).
One that comes to light is an ex BEA skipper who I knew who signed off on an Airprox..GASCO..concerning a chopper and a paraglider..biggest load of Rubbish but then in a previous life he was forced to resign after leaving a stick of Semtex on a 747 for a couple of weeks which circum navigated the globe until found by a cleaner (IIRC) - the Semtex...even he couldn't loose a 747!
Last edited by blind pew; 14th Aug 2016 at 20:22.