Frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. The technology is used in telecommunications, radio broadcasting, signal processing, and computing.
Surfing is a surface water sport in which an individual, a surfer, uses a board to ride on the forward section, or face, of a moving wave of water, which usually carries the surfer towards the shore. Waves suitable for surfing are primarily found on ocean shores, but can also be found in standing waves in the open ocean, in lakes, in rivers in the form of a tidal bore, or in wave pools.
The amplitude of a periodic variable is a measure of its change in a single period. The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of amplitude, which are all functions of the magnitude of the differences between the variable's extreme values. In older texts, the phase of a periodic function is sometimes called the amplitude.
In electronics, acoustics, and related fields, the waveform of a signal is the shape of its graph as a function of time, independent of its time and magnitude scales and of any displacement in time.
In mathematics and its applications, the root mean square of a set of numbers is defined as the square root of the mean square of the set. The RMS is also known as the quadratic mean and is a particular case of the generalized mean. The RMS of a continuously varying function can be defined in terms of an integral of the squares of the instantaneous values during a cycle.
A sine wave, sinusoidal wave, or just sinusoid is a mathematical curve defined in terms of the sine trigonometric function, of which it is the graph. It is a type of continuous wave and also a smooth periodic function. It occurs often in mathematics, as well as in physics, engineering, signal processing and many other fields.
Mavericks is a surfing location in northern California outside Pillar Point Harbor, just north of the town of Half Moon Bay at the village of Princeton-by-the-Sea. After a strong winter storm in the northern Pacific Ocean, waves can routinely crest at over 25 ft (8 m) and top out at over 60 ft (18 m). Routinely, waves that break can be recorded on seismometers. The break is caused by an unusually shaped underwater rock formation.
In fluid dynamics, a wind wave, water wave, or wind-generated water wave, is a surface wave that occurs on the free surface of bodies of water as a result of the wind blowing over the water´s surface. The contact distance in the direction of the wind is known as the fetch. Waves in the oceans can travel thousands of kilometers before reaching land. Wind waves on Earth range in size from small ripples to waves over 30 m (100 ft) high, being limited by wind speed, duration, fetch, and water depth.
Edward Ryon Makuahanai Aikau was a Hawaiian lifeguard and surfer. As the first lifeguard at Waimea Bay on the island of Oahu, he saved over 500 people and became famous for surfing the big Hawaiian surf, winning several awards including the 1977 Duke Kahanamoku Invitational Surfing Championship. The Eddie Aikau Big Wave Invitational is named in his honor. He was also a crew member on the Polynesian voyaging canoe Hōkūleʻa.
Nazaré is a Portuguese town and municipality located in the Oeste region, in the historical province of Estremadura, and in the Leiria District. The municipality has a population of 14,889 in an area of 82.43 km2, while the town itself has around 10,000 inhabitants.
A swell, also sometimes referred to as ground swell, in the context of an ocean, sea or lake, is a series of mechanical waves that propagate along the interface between water and air under the predominating influence of gravity, and thus are often referred to as surface gravity waves. These surface gravity waves have their origin as wind waves, but are the consequence of dispersion of wind waves from distant weather systems, where wind blows for a duration of time over a fetch of water, and these waves move out from the source area at speeds that are a function of wave period and length. More generally, a swell consists of wind-generated waves that are not greatly affected by the local wind at that time. Swell waves often have a relatively long wavelength, as short wavelength waves carry less energy and dissipate faster, but this varies due to the size, strength, and duration of the weather system responsible for the swell and the size of the water body, and varies from event to event, and from the same event, over time. Occasionally, swells that are longer than 700m occur as a result of the most severe storms.
Lagundri Bay, or Sorake Bay, is a horseshoe-shaped bay at the southern end of the island of Nias off the coast of Sumatra in Indonesia. It is a popular tourist destination and a noted surf break.
In fluid dynamics, a breaking wave or breaker is a wave whose amplitude reaches a critical level at which large amounts of wave energy transform into turbulent kinetic energy. At this point, simple physical models that describe wave dynamics often become invalid, particularly those that assume linear behaviour.
In physical oceanography, the significant wave height is defined traditionally as the mean wave height of the highest third of the waves (H1/3). Nowadays it is usually defined as four times the standard deviation of the surface elevation – or equivalently as four times the square root of the zeroth-order moment (area) of the wave spectrum. The symbol Hm0 is usually used for that latter definition. The significant wave height (Hs) may thus refer to Hm0 or H1/3; the difference in magnitude between the two definitions is only a few percent. SWH is used to characterize sea state, including winds and swell.
The Nazaré Canyon is an undersea canyon just off the coast of Nazaré, Portugal, in the eastern North Atlantic Ocean. It is the largest submarine canyon in Europe, reaching depths of about 5,000 metres (16,000 ft) deep and a length of about 230 kilometres (140 mi).
In fluid dynamics, the Ursell number indicates the nonlinearity of long surface gravity waves on a fluid layer. This dimensionless parameter is named after Fritz Ursell, who discussed its significance in 1953.
In fluid dynamics, the wave height of a surface wave is the difference between the elevations of a crest and a neighboring trough. Wave height is a term used by mariners, as well as in coastal, ocean and naval engineering.
In physical oceanography, undertow is the undercurrent that is moving offshore when waves are approaching the shore. Undertow is a natural and universal feature for almost any large body of water: it is a return flow compensating for the onshore-directed average transport of water by the waves in the zone above the wave troughs. The undertow's flow velocities are generally strongest in the surf zone, where the water is shallow and the waves are high due to shoaling.
This glossary of surfing includes some of the extensive vocabulary used to describe various aspects of the sport of surfing as described in literature on the subject. In some cases terms have spread to a wider cultural use. These terms were originally coined by people who were directly involved in the sport of surfing.
The North Shore, in the context of geography of the Island of Oʻahu, refers to the north-facing coastal area of Oʻahu between Kaʻena Point and Kahuku. The largest settlement is Haleʻiwa.
