Atmospheric Turbulence?

[Stardaze]

I've collimated my 5" reflector for the first time today and have had an hour just to check all is fine. It actually doesn't seem to be any different, but then I'm wondering whether there's turbulence around tonight. Presume at this time of year, and just into dark following a relatively warm day, there will be heat rising? When I defocus I tend to get almost rings in the centre, but broken up into dots, with a ring of fire around the centre that pulses a bit? Does that sound like atmospheric conditions? I'm likening it mostly to that mentioned in this article: http://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/