On Sunday, July 23, 2017 at 1:45:38 PM UTC-4, firsys wrote:
Yesterday, close to my home field, after I had given up( 2500 ft cloudbase)
I noticed lennie like clouds lining up across the light NW wind.

I have flown thermal wave often in the past, but nothing in the last ten years.
Missed this one but probably too weak to use.

These systems can difficult to get into but extensive and rewarding if you can do it.

Has anyone any idea of the met conditions for development of T.W?

Here are a couple:

Weak convection in the lower layer with light winds.

An upper wind of 15+ kts above an inversion, rising with height.

But there must be something else or I would see this more frequently.

John Firth
Ottawa

PS In the last ten years or so, here in E Ontario, it has not been common, or even frequent as it was in the 70s and 80s; I have been looking to fly any day since 2008 and think I would have noticed.
(BTW I published a paper in the OSTIV journal reporting a flight to 16000
ft after a low level struggle in weak convection; I think it was presented at the 1978 meeting at Chateauroux)