On August 27, 1883, the volcanic island of Krakatoa in the Sunda Strait unleashed one of the most violent eruptions in recorded human history. The cataclysmic blast ruptured the ear drums of sailors forty miles away and produced a detonation heard over 3,000 miles away. Beyond audible sound, the explosion generated a colossal atmospheric pressure wave that expanded outward around the globe.
Traveling at roughly 700 miles per hour, this air wave reached London, over 7,000 miles away, in about ten hours. Meteorologists across Europe noticed strange, sudden spikes on their barographs. Remarkably, the pressure wave did not simply dissipate after reaching the far side of the world; it converged at the antipodal point in North America and bounced back.
For five days, this atmospheric wave bounced back and forth between the eruption site and its opposite point on the globe, circling the planet up to seven times in total. Scientists monitoring barometric charts in London and Greenwich watched in fascination as their instruments recorded distinct pressure spikes every 34 hours as the echoing pulse passed through, marking a historical milestone in global meteorology.