Hot, moist exhaust from the campus power plant stacks mixed with frigid air this morning to produce some great turbulent flow and even some “mixing clouds.”  (Video is 90 seconds; I zoom in a bit at 60.)  My favorite part: notice that the interior of each plume remains somewhat clear–that’s the part of the “updraft” that entrains ambient air last, so in this case, it stays clear the longest.  Neat!

As for the clouds, this is the same process that causes airplane contrails, and your breath to appear in winter.  For more information, here’s the AMS Glossary definition of mixing clouds and here’s a quick explanation using temperature and vapor pressure from the Hong Kong Observatory.

I’ll look for a couple of good explanations & links related to entrainment and update this when I have the chance.