The Sound So Loud That It Circled the Earth Four Times

On 27 August 1883, the Earth let out a noise louder than any it has made since. It was 10:02 AM local time when the sound emerged from the island of Krakatoa, which sits between Java and Sumatra in Indonesia. […] By 1883, weather stations in scores of cities across the world were using barometers to track changes in atmospheric pressure. Six hours and 47 minutes after the Krakatoa explosion, a spike of air pressure was detected in Calcutta. By 8 hours, the pulse reached Mauritius in the west and Melbourne and Sydney in the east. By 12 hours, St. Petersburg noticed the pulse, followed by Vienna, Rome, Paris, Berlin, and Munich. By 18 hours the pulse had reached New York, Washington DC, and Toronto. Amazingly, for as many as 5 days after the explosion, weather stations in 50 cities around the globe observed this unprecedented spike in pressure re-occuring like clockwork, approximately every 34 hours. That is roughly how long it takes sound to travel around the entire planet.

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