On Thursday, September 6, 2018 at 7:23:31 PM UTC-4, Andy Blackburn wrote:
Mike,

I understand that the short period response to a step function in vertical air motion would damp out after less than a second, but normally thermal entry would have a positive gradient in vertical air motion as the glider traverses from zero vertical motion to maximum vertical motion towards the center of the thermal. This ought to create a more prolonged nose-down pitch attitude in addition to upward acceleration, both of which ought to be detectable to accelerometers and gyros in a modern vario. This would be quite distinct from an ever-so-slow negative acceleration and nose up pitch rate from a horizontal gust on the nose. I expect having a sense for the distribution of strength and duration for horizontal gusts would also help a bit.

That’s what I tend to sense in moderate to strong thermals versus gusts. Is that that a correct interpretation?

Andy

I recently took a "refresher"course of four days with a truly outstanding professional mountain soaring pilot. Interestingly, he does not detect and select thermals by using the vario. He states that the vario gives old information that has long past. Intead, he trusts his "butt" and for a visual reference notices the nose of the glider pitching upwards. We seldom missed a true thermal. When a glider enters sink )as when leaving a strong thermal), the nose pitches upwards initially.