In the days of Concorde, we in the south west used to get this double boom most days, although it was a deeper boom, rather than the 'crack' in the clip. Always impressive and more or less the same time.
Does anyone else remember this?
What we heard here, perhaps because we are between high mountains, were two real booms (as you say not "cracks" like in the clip) and we thought that they must have been blasting for road works or excavations on the other side of the lake. It has happened that we have heard similar booms at night and thought they were night roadworks or some such. Perhaps in our area this sort of thing occurs more often than one would suspect. There are may times when we see military jets on daytime training runs along the lake and at times I have been up in the mountains at 1,000 metres and seen them pass at a lower level, probably 500 metres or less above the lake.
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