The latter are “secondary” transverse waves like light waves. The former are “primary” longitudinal waves like sound waves. Of course in seismology we have P-waves and S-waves. Wikipedia says the propagation velocity depends on the density and elasticity of the medium, and is up to 13 km/s in the deep mantle. In diamond it’s circa 12,000 m/s or 26,843 mph. In steel it’s circa 6000 m/s or 13,421 mph. The speed of sound in sea water is circa 1500 m/s or 3,355 mph. Celeritas means swiftness or speed, which varies according to the properties of the medium. See Wikipedia and you can read that the speed of sound “is conventionally represented by c, from the Latin celeritas”. You steer a tank to the left in a similar fashion, by slowing down the track on the left. The mud slows down the wheels on the left, so the car pulls to the left. The sonar waves “veer” rather like a car veers when it encounters mud at the side of the road. So a horizontal sonar wave tends to get refracted downwards: Image from FAS and the US Navy, see course ES310 chapter 20 It’s similar for sound waves in the sea, but there the speed of sound typically decreases with depth. Interestingly enough, the speed of sound typically decreases with increasing altitude, so sound tends to get refracted upwards. At that altitude the speed of sound is circa 295 m/s or 660 mph, which is one reason why passenger jets don’t fly as fast as you might like. That’s about 36,000 feet, which is typical for a passenger jet. It usually decreases with altitude up to about 11 kilometres above sea level. The speed of sound in air is sometimes said to be 343.2 metres per second or 768 miles per hour.
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