Is anybody familiar with a conducting technique in which the conductor adds a small circle, curlicue, to the conducting hand when she wants the ensemble to take a breath? My impression is typically when the hands stop the music stops --time to take a breath-- when the hands are moving the music is moving and the beat goes on. Any help interpreting would be appreciated.
What you're describing sounds like a distracting motion to me. There's a time and place for everything, but this doesn't sound like a good way to do it.
As a conductor, the easiest way to get the ensemble to take a breath is to take a breath yourself. It's actually critically important to do so to get the piece started, and something that non-wind players often struggle with as beginning conductors.
For visual emphasis, you could add a little extra vigor to an upstroke. That's effective because it mimics the natural motion of taking a quick breath. I don't see how little circles is in any way an indication to take a breath.