I wouldn't take this too seriously. Annual rituals are tied to visible phenomena such as cycles of the sun or moon, plus the observation of seasonal effect. Air pressure? Hardly a reliable factor given that it varies considerably and often - one only has to look at the television weather report to see regions of low and high pressure wandering across the globe bringing sun or rain, and quite how the ancients were aware of this connection is beyond me.
For that matter, it ought to be remembered that Stonehenge is not a single isolated relic of the past, it is part of a ritual landscape across a wide swathe of the area in England including pathways, burials, and even some kind of perimeter. There is no connection whatsoever with Egyptian pyramids which were a cultural phenomenon linked to belief in the divinity of their rulers and the egos of those rulers.