January 2022 Archives
Mon Jan 17 09:39:05 CET 2022
Hunga Tonga affected the air pressure in my apartment
Hunga
Tonga–Hunga Haʻapai was a volcanic island in Tonga.
Was (past tense) because
a volcano erupted there a few dats ago on 14 Jan 2022, and
probably destroyed most of the island, as well as sent a tsumani
across the Pacific ocean, and a wave of pressure through the
atmosphere, detectable all the way around the world.
Jeremy
Cole reported seeing two pressure waves from the eruption arrive in
Nevada. (The first was the shorter way around the planet, and
the second was the longer way.) For the longer path, the speed
calculated is 689 mph, or 1108 kph. (It was a little faster for the
shorter path.) Google maps tells me the distance from Hunga Tonga
to Berlin, DE is 16,375 kilometers, the shortest path (heading
North and West).
16,375 km / 1,108 kph = 14 hours and 47 minutes.
The time of the eruption reported in the graphic supplied by Jeremy Cole is 04:14:45 UTC. So 04:14 + 14 hours and 47 minutes is 19:01, Berlin is UTC+1, so add another hour and i'd expect to see the first wave arrive around 20:00.
I don't recall noticing the change in air pressure, but i think the Airthings Wave Plus sensor in my apartment did:
... beginning about 20:10, there's a sharp increase and then
recovery, which matches the shape of the first wave in the chart
for Nevada.
Google Maps and Google Earth only seem to want to give me the
shortest path between two points, but maybe i can work out the
longer path with a bit of math. Wikipedia says the
circumerence of the Earth is 40,075 km around the Equator, and
40,008 at the poles, so just splitting the difference between the
two that's 40,047 km. (I imagine one can compute the distance
across the surface of a slightly imperfect sphere-shaped object,
but i do need to start my day job soon...)
So we subtract the short path from the (averaged) circumference,
and...: 40,047 - 16,375 = 23,672 km.
23,672 km / 1,108 kph = 21.36 hours.
04:14 UTC + 21 hours and 22 minutes + 1 hour (Berlin is UTC+1) = 02:35 Sunday morning, which is about 10 minutes earlier than the 2nd wave shows up. Maybe it was slower than the 1,108 kph observed in Nevada -- perhaps it loses some speed the further it travels.