Overnight minima and inversion

An interesting chart of overnight minimum temperatures [18-06] across Scotland from the SYNOP observations on what was a fairly cold night for the end of Summer (19-20 September 2019), with Tulloch Bridge just registering an air frost (-0.1°C). The temperature at all the Scottish hill stations held up very well, and the overnight minimum at Cairnwell was as high as 13.4°C, which goes to show the strength of the inversion which quickly formed under the ridge of high pressure and must be at around 1500 feet I would have thought. At this point I would like to back that last assertion with a look at the midnight ascent from Shanwell, but as the UKMO closed all radiosonde stations in Scotland (apart from Lerwick) a number of years ago I can’t do that.

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