Waves occur in a variety of shapes and sizes. While all waves have certain fundamental qualities and behaviors in common, some waves may be identified from others based on observable and some non-observable traits.
Ocean waves are definitely not transverse. In fact, these waves are a unique phenomenon since they share characteristics of both longitudinal and surface waves.
Longitudinal Waves
In a longitudinal wave, the particles of the medium travel in a direction parallel to the wave’s movement. Such waves are distinguished by particle motion that is parallel to wave motion.
Think of a sound wave flowing through the air. As the wave travels, particles of air vibrate back and forth in the same and opposite directions of energy transmission.
Each particle pulls on its neighboring particle to propel it onward. The back and forth motion of particles in the direction of energy transmission produces parts inside the medium where particles are squeezed together and other regions where particles are spaced apart.
The existence of such zones may always be used to easily identify longitudinal waves. This process continues throughout the particle chain until the sound wave reaches the listener’s ear.
Transverse Waves
A transverse wave is one in which the particles of the medium travel perpendicular to the direction of the wave. Transverse waves are differentiated on account of particle motion that is perpendicular to wave motion.
For this example, let’s take a slinky spring that is stretched horizontally across a room. By shaking the left end of the spring in an up and down motion, a pulse is inserted. Energy will start to flow through the spring from left to right.
You could see the individual coils of the medium get shifted above and downwards as the energy is carried from left to right. In this situation, the medium particles travel perpendicular to the direction of the pulse.
Ocean Waves
Transverse waves and longitudinal waves can move through a solid material. However, waves that move through the bulk of a fluid, such as the ocean, are always longitudinal.
Transverse waves must transport their energy through a somewhat stiff medium. When one particle starts moving, it must be able to pull on its nearest neighbor. If the medium is not stiff, as fluids are, the particles will move past one other.
This sliding action is unique to liquids and gases. It keeps one particle from displacing its neighbor in a direction perpendicular to the energy transmission. As a result, only longitudinal waves can be seen traveling through the bulk of liquids such as our oceans.
While waves that move inside the depths of the water are known as longitudinal waves, waves that travel over the ocean’s top are known as surface waves.
A surface wave is a wave in which medium particles move in a circular motion. Surface waves have no longitudinal nor transverse characteristics.
The Crux
In longitudinal and transverse waves, all particles in the medium travel in parallel and perpendicular directions to the direction of energy transmission, respectively. Whereas in a surface wave, only the particles at the medium’s surface move in a circular motion. Particle motion tends to diminish as one moves away from the surface.
