A swell in the ocean is a series of mechanical waves that propagate along the interface between water and air. It is formed through a combination of wind strength, wind duration, and fetch. Swell waves often have a relatively long wavelength, which means they carry more energy and can travel long distances without significant changes in height or shape. Swells are not greatly affected by the local wind at the time of their formation.
The main characteristics of a swell are:
- Long wavelength: Swell waves have a longer wavelength compared to other types of waves, which allows them to travel long distances without dissipating quickly.
- Smooth tops: Swell waves usually have smooth tops, making them difficult to detect with the naked eye, especially when they are not significantly larger than the normal waves.
- Deep-penetrating energy: Longer swell periods indicate a swell with deep-penetrating energy that will be forced to the surface when the swell approaches the coast, producing a wave up to one and a half times taller than the swell was over open water.
- Organized and well-defined: Swells can pass through and under other swells, absorbing them in their path and resulting in more organized, well-spaced, and well-defined swell lines.
Swell is often confused with sea, which refers to the local wind-generated waves in a particular area. Swell, on the other hand, is a separate entity that has moved beyond the area where it was generated.
