This is evident if you have ever watched an object such as a seabird floating at the surface. As a wave passes, water moves forwards and up over the wave crests, then down and backwards into the troughs, so there is little horizontal movement. This orbital motion occurs because water waves contain components of both longitudinal (side to side) and transverse (up and down) waves, leading to circular motion. Instead, the water particles move in circular orbits, with the size of the orbit equal to the wave height (Figure 10.1.3). Therefore, the longer the wavelength, the faster the wave.Īlthough waves can travel over great distances, the water itself shows little horizontal movement it is the energy of the wave that is being transmitted, not the water.

Speed: how fast the wave travels, or the distance traveled per unit of time.

Frequency: the number of waves passing a point in a given amount of time, usually expressed as waves per second.

Period: the time it takes for two successive crests to pass a given point.

There are also a number of terms used to describe wave motion: height exceeds 1/7 of the wavelength) the wave gets too steep, and will break.įigure 10.1.2 Components of a basic wave (Modified by PW from Steven Earle “Physical Geology”).

Wave steepness: the ratio of wave height to length (H/L).

Wavelength: the distance between two identical points on successive waves, for example crest to crest, or trough to trough.

Wave height: the distance between the crest and the trough.

Still water level: where the water surface would be if there were no waves present and the sea was completely calm.

There are several components to a basic wave (Figure 10.1.2): The ripple pattern is a result of internal waves in the atmosphere (NASA, via Wikimedia Commons). These often create ripple effects in the clouds (Figure 10.1.1).įigure 10.1.1 Wake patterns in cloud cover over Possession Island, East Island, Ile aux Cochons, Ile de Pingouins.

Atmospheric waves form in the sky at the boundary between air masses of different densities.

The giant wave in Lituya Bay that was described in the introduction to this chapter was a splash wave.

Splash waves are formed when something falls into the ocean and creates a splash.

They are also called seismic sea waves ( section 10.4).

Tsunamis are large waves created as a result of earthquakes or other seismic disturbances.

Tidal waves are not related to tsunamis, so don’t confuse the two. What we think of as tides are basically enormously long waves with a wavelength that may span half the globe (see section 11.1).

Tidal waves are due to the movement of the tides.However, the height of the deep wave would be unnoticeable at the surface. These generally move more slowly than surface waves, and can be much larger, with heights exceeding 100 m.

at a pycnocline), and propagate at depth. Internal waves form at the boundaries of water masses of different densities (i.e.We are most familiar with the kind of waves that break on shore, or rock a boat at sea, but there are many other types of waves that are important to oceanography: Waves generally begin as a disturbance of some kind, and the energy of that disturbance gets propagated in the form of waves.

Types of ocean waves