Whilst watching a short video by Alex McColgan on the YouTube cosmology channel, Astrum, I learned that the the recent eruption of the Tongan volcano Hunga Tonga–Hunga Haʻapai sent a pressure wave all around the globe (several times). This had me scrambling for the data produced by the pressure sensor that is part of the Push Bikes air quality sensor, and sure enough, the pressure wave is visible. The first shock wave (with a peak-to-peak value of 2.5 hPa) can be seen starting just after 1830, and the second wave at about 0140 the next day (enlarged image). Between the two shock waves, and for a while afterwards, the atmosphere remains disturbed, like the water in a pond after a rock has been thrown in. This is confirmed by the UK Met Office, who measured the same disturbance.