20 Facts About Waves

#1. Waves comes from a word meaning “to join” or “to celebrate.”

facts about waves

#2. The highest wave ever recorded was the tsunami caused by the 1960 Valdivia earthquake, which was measured at 173 feet tall at Aonae, Chile. It is thought that this earthquake produced waves 200-300 feet tall, and a runup of 10 meters occurred over a large coastline area.

#3. The shortest wavelength in nature occurs when water crashes in a container with a diameter about an inch less than its height: it forms a droplet with perfectly round bottom and flat top. This phenomenon is called buckling and can be observed when using glassware made according to the old German standard (the so called Reagertuben).

#4. The first person to study surface tension effects on waves was Isaac Newton, who observed that a floating needle is always placed with its point towards the direction from which the next wave will arrive.

#5. In the past, people have danced on waves. This is called a dance wave and was popular in Croatia until the early 20th century.

#6. A wave on the surface of deep water is an example of a non-dispersive wave, in which the energy is moving in one direction only. By contrast, waves with changing amplitude (alternating peaks and troughs) are called dispersive waves.

#7. A ring thrown down on a liquid surface will spread out into an almost perfect circle because gravity pulls it downwards equally in all directions at once. But if the surface is vibrating up and down as it would do in a wave, the ring will be pulled towards its peaks and troughs, lengthening vertically so that its vertical cross section also turns into a more or less elongated figure of eight.

#8. The wavelength of green light is between 500 – 570 nanometers (0,000 000 565 – 0,000 000 535 millimeters)

facts about waves

#9. The speed of a tsunami can be as fast as a jet aircraft — for instance the 2004 Indian Ocean earthquake and tsunami waves were traveling at speeds between 500 – 1,000 km/hr (310 – 620 mph).

#10. The most powerful storm waves result form winds blowing across hundreds or even thousands of miles of open water. These waves can cause damage to offshore structures and ships, as the North Atlantic storm of 1987 proved when it sank several oil rigs and fishing boats and caused large ships such as tankers and container ships to be literally thrown onto the rocks onshore by the 30-foot waves.

#11. The Coriolis effect is important because it affects the circular motion of waves. For example, if you put a stick into the surface of calm water in the Northern Hemisphere, waves will appear to travel clockwise around its tip. If you do the same thing in the Southern Hemisphere, they’ll go anticlockwise.

#12. The wavelength is twice as long as the swell period.

#13. The smallest wavelength you can see is the blue-violet light with a wavelength of 380 nanometers.

#14. Ships can surf on some very large waves, as has been demonstrated by the US Navy in experiments on the Columbia River bar off the Pacific Northwest of America where ships have ridden waves as high as 29 feet.

#15. When a ship first starts to move it rides over the first wave, then begins plunging into deeper water where this first wave is developing into a peak and trough system which, by coincidence, matches up with its own length so that it does not produce any net upward or downward motion – rather like when we stand still but our knees rise and fall an inch depending on whether our weight is on one leg or the other.

But as it speed up, it starts to catch waves at a slant and begins to rise and fall, alternately climbing the waves and falling between them.

#16. In the case of a storm wave approaching a ship, because its speed is much higher than that of any surface wave in deep water, at first there is no obstacle to its passage through the sea, so it accelerates and becomes steeper as it advances.

At a point very close to the shoreline where waves have their maximum height this steepening causes unstable collapse – the top of each wave curls over while part or all of it plunges downwards. The sudden increase in depth due to this ‘plunging’ allows the next incoming swell to catch up with it before it rises again.

This process then repeats itself until finally when they are near enough to the shore for bottom friction to become important the plunging gives way to surging.

facts about waves

#17. I have calculated that the speed of a tsunami is about 6,000 miles per hour or 3,700 feet per second. If it were not for land friction slowing down the wave, there would be no obvious limit to how large a tsunami could grow theoretically since its speed depends mainly on the depth of the water in which it travels.

#18. When an object moves in a circular path at constant speed then acceleration towards or away from the center of rotation is zero and so centripetal force must also be zero by Newton’s first law of motion.
But when waves enter shallows they are forced to change direction toward the normal line between the center of the earth and the water level. This point is called the ‘center of curvature’. Since it is at a finite distance from the center of rotation around that center, centripetal force must act on a wave as it approaches a shore to turn its velocity vector toward this new direction.

#19. It was once thought that basins were filled with water, sloping gently upwards so that waves approaching land tended to break from an almost level surface but in reality most of them break over submarine ridges or banks which generally have slopes of up to about 10 degrees – corresponding to a fall of more than 4 meters per kilometer of length for typical trough depths between 0.3 – 1 meter. So breaking waves would tend to travel faster over these ridges than in deeper water.

#20. A wave is said to ‘damp out’ when the surface velocity falls below 10% of its peak value. This can happen either because it slows down until the troughs catch up with the crests, or because one crest overtakes another ahead of it.

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