I know about the seasonal changes of the altitude of the tropopause as well as the differences by latitude. I thought the change at one location was a very slow process, but I just found upper air observations through radiosounding from Iceland where I could see that the altitude of the tropopause changes up to 7000ft (over 2km) within 12 hours, such as:
What exactly happens in the atmosphere when the altitude of the tropopause changes that rapidly? Is air moving horizontally? Vertically? Is air exchanging heat energy with surrounding air? My best guess would now be that since the polar jet stream is above Iceland, it transports vast amounts of air, so an observer in Iceland each day sees different atmospheric conditions when looking upwards. How close to reality is that guess?