SIS and NVC, Thanks for the responses. That amount of turbulent mixing is more than I was intuitively thinking would happen. Sorry, some more questions
Again intuitively, the turbulent mixing is greater the less the density difference between the warm intruding air and the cold air in the temp. inversion block? So, one way to quickly disrupt the temp. inversion would be a sequence of intrusions, starting with air just a bit warmer than the temp. inversion (to maximise mixing) and then subsequent warm air intrusions gradually increasing in temperature?
Carrying this on in a thought experiment, there is a density difference at which any intruding air wouldn't have any impact on the temp. inversion block? That is, there is a temperature difference at which to all intents and purposes the intruding warm air would just rise up and over the cold air mass and not move, mix with or impact the temp. inversion? Any ideas what this temp. difference would be?