Steve Moyes was once quoted as saying, “I just keep circling until I make a thermal.”
This response was to the question about whether or not he sold his soul to the devil to find thermals so low.
Most everyone was sure it was a tongue in cheek statement. --- Not me.
Crop dusters dive at a crop field and make the first pass without releasing their spray to break off any thermals that would carry away their spray --(They know what their doing.)
Sailplane pilots dive at the ground to break off thermals to ascend in. (They know what their doing.)
Several times when low I have tried to start a thermal up by circling above a small knoll (trigger point) in a tilled field as I was sinking out. Far more times than not I got back up and continued on my way. I usually wound up eventually having to turn the other way and circle once I was high enough to safely make the maneuver and not fall out of the thermal. That way I would be turning against the rotation of the thermal.
By the way if you spend one summer flying over the flat fields in central Washington state where almost all thermals are marked with the fine talc like dust that is everywhere in that area you will be convinced that the hemispheric rule has nothing to do with the direction a thermal turns.
Just as many turn counter clockwise as turn clockwise.
I’ve flown there over ten different summers and I took note of the direction that thermals turn and it is a fact beyond any reasonable doubt that the hemispheric rule holds little to no sway over the rotational direction of something as small as a dust devil.
I once watched a pilot sink out and land on the flat farm (dirt) field after he had crossed the Columbia River. He had launched from Chelan Butte, WA.
As he flared a right wing tip vortex turned into a dust devil that saved me from landing with him.
While going cross county following Hwy 2 east toward Spokane, WA I have seen many dust devils start from the back of traveling 18 wheelers.
During the 1985 and again in 1995 Nationals my wife would see me get low and she would drive with the vans right wheels in the loose field dirt and raise the fine powdered dust to mark thermals that saved the flight. (possibly creating thermals too.)
During the Nationals I would hear pilots radio their chase vehicles and ask which way the wind was blowing.
I would think, hey dummy were drifting east isn’t that enough for you to make up your mind?
Then the driver would stop check and radio back that the wind was out of the south. Until that moment I thought the pilot was just trying to make the driver feel important and boost their ego.
This was my aahaa
moment. If the wind was out of the south the thermal was north of the chase vehicle. (Gee but I can be slow learner at times!
If you run across a list of pilots that believe that they can trigger a thermal low by circling over a trigger point, put me on that list with them!
PS (Edit) At altitude: Dynamite, Railroad flares over dry grass are two that come to mind.