In April , a foot wave crashed down on the Norwegian Dawn cruise ship. The average waves that day were 25 to 30 feet high before this monster wave struck.
The wave even damaged the ship's hull. What causes these enormous waves? Generally they form because of swells, while traveling across the ocean, do so at different speeds and directions. As these swells pass through one another their crests, troughs, and lengths happen to coincide and reinforce each other, combining to form unusually large waves that tower then disappear. If the swell are traveling close to the same direction, these mountainous waves may last for several minutes before subsiding.
It is very seldom that huge waves over 65 feet 20 meters are developed and normally sailors do not even see them, because ships nowadays will try to avoid such conditions by altering course before the storm hits.
But they do occur. Please Contact Us. Toggle navigation JetStream. Wind, Swell and Rogue Waves The wind not only produces currents, it creates waves. When the wave ran ashore, it snapped trees 1, feet upslope. Five deaths were recorded, but property damage was minimal because there were few cities or towns nearby. Ask Smithsonian A Smithsonian magazine special report. On rare occasions earthquakes and landslides can generate waves, but usually waves are created by wind.
Generally, the biggest and most powerful wind-generated waves are produced by strong storms that blow for a sustained period over a large area. Think for a few seconds about what happens when you throw a stone into a serene pond. The waves that surfers ride originate in distant storms far across the ocean. The waves within a storm are usually messy and chaotic, but they grow more organized as they propagate away from the storm and faster waves outrun slower waves.
When describing a swell, oceanographers and surfers generally care about three attributes. First, the height — how tall a wave is from the bottom to the top. Then the wavelength — the distance between the top of one wave and the top of the wave behind it.
And finally the period — the time it takes for two consecutive waves to reach a fixed location. Waves caused directly by the local wind are called wind waves. Wind waves are short, choppy, and tend to break white cap when winds reach approximately 17 miles per hour. Compared to wind waves, swell are longer waves with smoother crests. Wave height is the measurement representing the size of the wave. Waves have two main parts. The wave crest is the top part of the wave and what people commonly refer to as a wave.
The second half of the wave is the trough, the low point that comes in between two wave crests. A series of wave crests and wave troughs of different heights, frequencies, and directions is referred to as the wave spectrum.
The wave height is the vertical distance between the wave trough and the wave crest. There are several different ways wave height is reported.
This is the same wave height value that the NOAA marine forecast uses. It is as the average height of the highest one-third of waves in a wave spectrum and closely corresponds to what a trained observer would consider to be the average wave height.
Devised by oceanographer Walter Munk during World War II, the significant wave height provides an estimation of wave heights recorded by a trained observer from a fixed point at sea. The greatest number of waves is indicated by the widest area of the spectrum curve. Note that the highest wave height of an individual wave will be significantly larger.
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