The direction from which a swell comes from will make the waves break differently on the approaching shoreline. Offshore winds are ideal for surfing because the groom the waves surface and can result in a barreling wave. Ideal conditions for surfing would include absolutely no wind.
This is called glassy conditions, and a surfers dream scenario. On shore winds blow from the ocean towards the shore. These types of winds are terrible for surfers because it causes a choppy and bumpy surface which is harder to surf on. On shore winds break up the swells causing the wave height to be smaller and not as groomed. Some surfers who like to perform aerial maneuvers with their surfboards welcome a bit of onshore wind because it helps keep their surfboards close to their feet when in the air.
Onshore wind can help surfers keep their surfboards under their feet when performing aerial maneuvers. Off shore winds are the best kind of wind to have when surfing next to no wind of course. Off shore winds blow from land into the water creating very smooth and well groomed waves that can typically take a barrel shape.
Off shore winds can be a problem when blowing to hard though. Surfers taking off on a wave can get blown back by the wind or sprayed with a large mist of water from the cresting wave making it hard to see as you drop in.
Knowing the wind direction and speed for your surf spot will help you decide which the best time to go out for surf is. Generally, most surf spots will have calm and glassy seas in the early morning with the wind picking up in the afternoon hours and then calming down again in the evening.
Learning how tides work at your local surf break will help you determine when the best waves will be breaking. The tide can have a major role on the way a waves breaks at a particular surf spot. Much the same in how wind direction is shown, the arrow shows the direction the swell has travelled from.
Typically coastlines will receive incoming swells from one or two predominant directions. In the same way, as regional areas receive prevailing winds from a particular direction due to its geographical location and weather systems. The direction that a beach faces, the topography of the seabed and the angle the incoming swell reaches these features will have a huge effect on how waves form and break.
With oceans being so vast and so easily affected by varying winds, multiple swells are formed within relatively small areas, resulting in multiple swells travelling towards or reaching coastlines within the same period of time. In this scenario, the different swells are categorised according to their wave period, direction and swell height. Swell height refers to the average size of the swell out at sea.
This is measured from the peak to the trough and the seconds between one peak and the next using historical and real time data gathered from offshore buoys.
Depending on the swell model used by differing surf forecasting websites each may show a slight difference in wave height. Swells and the individual waves within a swell travel at different speeds. For the swell to keep moving forward, individual waves are constantly rotating positions. In order to work out the speed that a swell is travelling multiply the wave period by 1. The result is the speed the swell is travelling in knots. Wave decay refers to the energy loss within a swell as waves propagate outwards from where they were generated.
The further the distance travelled the more energy is lost and is dissipated. Surf forecasting websites have become very accurate over the past 10 years. The introduction of nearshore swell models, the ease of gathering meteorological information and the freedom of data provided by NOAA has allowed surf forecasting sites to provide detailed relative information for surfers. Combined and developed with local impressions surf forecasting websites are at the forefront of surfing.
However, the caveat remains that understanding and interpreting the data provided is a personal expectation that needs managing. As waves reach the shallow water of the coastline the wave runs out of space. Think of the wave as a recirculating sphere that rotates towards the shore, as the seabed becomes gradually steeper and the depth of water decreases more of the waves energy is forced upwards towards the surface, gradually increasing the height of the wave.
Waves with a longer period have more energy and so more water is forced upwards creating a larger wave. The topography of the seabed will affect how quickly a wave will form and how it will be break.
Waves that travel from the deep ocean and reach a sharp incline will form quickly and break fast. Wave buoys give surf forecasters a real time idea of what is happening out at sea. Contrary to common beliefs wave buoys do not provide much information for day to day surf reports.
Our 'primary' swell is the one we think is likely to make the largest and most powerful waves on the beach and is what our ratings and 'surf' heights are based on. Something very much like the average set wave. It's measured from the trough very lowest point to peak very highest point of each wave.
Generally speaking the larger the swell the larger the waves it'll create. While this should be fairly obvious it's complicated because longer period swells also make larger waves in shallow water and the direction of the swell will also have an effect so these factors are important too.
Swell period is literally the time it takes for successive waves to pass the same point in seconds. Practically the peak period of a swell gives a great idea of how powerful the swell is and how likely it is to create good waves for surfing. A groundswell is a group of traveling waves that left the generating area and propagated by itself for vast distances.
When they reach the shoreline, it has already accumulated a lot of energy and period in seconds between consistent and powerful wave trains. On the contrary, the wind swell - also called windsea - is a short-lived swell generated by local winds. These disorganized, short-period swells are common in the North Sea, Baltic Sea, and the Mediterranean Sea, although they can be seen anywhere in the world.
The swell period is the amount of time it takes for two successive wave crests to pass through a determined point. Long-period swells harness energy, travel faster, and easily cope with local winds and currents, resulting in larger beach waves. The first waves of a long-period swell are called forerunners and usually move faster than the remaining carriages of the wave train.
The swell height corresponds to the average size of the highest one-third of the waves in a given period. It is measured from trough to peak. The seconds between one peak and the next can be determined by ocean buoys to calculate swell height. The harder the wind, the greater the distance it blows on the fetch, and the longer the period, the bigger the wave, the longer the wavelength, and the longer the period between crests will be observed. A sustained and consistent knot wind blowing for nearly three days over a minimum distance of 1, miles 2, kilometers could generate wave heights of 50 feet 15 meters.
Swell direction is the direction from which it is traveling, and it is measured in degrees or cardinal points. As waves propagate away from the source, they start grouping into swell lines and traveling and spreading in a circumferential dispersion. In terms of wavelength, the longer the distance between two crests, the faster the waves will travel across the open ocean, meaning that faster waves with longer wavelengths will progressively overtake the slower, shorter wavelength swells.
Scientifically speaking, wave grouping is the result of different swells traveling in the same direction and merging together. However, when the peak of one wave-train coincides with the trough of another, a canceling out effect occurs, resulting in lulls at the beach. There's widespread and understandable confusion as to what the difference between swell and waves is. A swell is a group of waves that have gathered enough energy from the wind to reach another stage of maturity that allows them to travel well beyond the place of their origin.
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