Chris OCallaghan wrote:
Two out of three thermals (very unscientific study on my part) favor a
right turn. This is the result of the internal circulation of the
thermal. This adds yet another variable to the complexity of
thermalling. I'll leave it up to you to figure out how lift strength,
horizontal and vertical lift profile, vorticity, and turn direction
affect climb performance. Suffice to say in this short note that they
do.

There was a discussion in Soaring (maybe 15 years ago) on this
subject, with a nay sayer concluding, if thermals had spiral
circulation, you could look up and see clouds rotating. Well, I spent
an hour on my back the following weekend and found that they did, and
favored clockwise 2 to 1.

Where do you fly? I've never seen clouds rotating, and I've been soaring
for 25 years. I have seen dust and other objects in thermals rotating
several thousand feet AGL.

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Eric Greenwell
Washington State
USA