“Its the change in air pressure causing the moisture to condense I believe”.
Absolutely correct. And, the sound barrier doesn’t need to be broken for the phenomena to display itsself. The cool cone pattern is often seen at low altitudes along coastal areas, where the change in pressure does not require very high speed.
Since 1972, supersonic speed over the contintal US has been illegal. Althought the FAA has no jurisdiction over military operations, in this case the DOD compys except over certain MOA’s and segments of training routes.
I know the combination of cold water and air moving across a narrowing Lake Superior can cause some dense fog off Whitefish point on otherwise bright and sunny days.
Last time I was up there it was sunny most of the way till we got out on the point and it seemed overcast and by the time we stood on the beach we could barely see the water.