How Waves Are Made
37 commentsWaves are generated by wind. Offshore storms generate winds which blow on the surface of the sea and create ripples, much in the same way as the ripples in your post surf cuppa are made when you blow on it to cool it down. The wind can be seen on weather maps as low pressure areas. The more tightly packed the isobars are on the weather map the stronger the winds will be. Small waves (capillary waves) are initially generated in the direction that the wind is blowing.
Wind blowing on the Flat Sea Surface
The stronger and longer the wind blows, the more effect it has on these ripples and the larger they become. Initially the waves will just be small chop, but these will soon increase in size.
Constant Wind Creates a Larger Swell
As the wind continues to blow and the waves generated remain under the influence of the wind, the smaller waves will increase in size. The wind will get hold of the small waves much more easily than the calm sea surface.
The wave size is dependent on the wind speed generating it. A certain wind speed will only be able to generate a wave of certain size. Once the largest waves that can be generated for a given wind speed have formed, the seas are "fully formed."
Large Groundswell
Waves being generated have differing speeds and wave periods. (See wave terms explained for more detail.) The longer period waves are faster and move farther ahead of the rest of the slower waves. As the waves travel farther away (propagate) from the wind source, they start to organise themselves into swell lines. "Wave trains" form and these inevitably hit the beach at the same time. You may have heard of sets already!
Waves that are no longer affected by the wind that generated them can be referred to as ground swell, gold dust for surfers!
What Affects the Size of Swell
There are three main factors that affect the size of a wave in open sea.
- Wind speed - The greater the wind speed is, the larger the wave will be.
- Wind duration - The longer the wind blows, the larger the wave will be.
- Fetch - The greater the area the wind affects the wave, the larger the wave will be.
Once waves are no longer affected by wind, they'll start to lose their energy. They'll travel as far as they can while being decreased by friction on the sea bed and obstacles in the way. (A big island for example)
There are different factors affecting the wave size at a certain surf break. Examples include:
- Swell direction - Will the break be "open" to the current swell direction?
- Ocean floor - A swell coming straight from deep sea up onto a reef will generate big, barreling waves. A long, shallow ledge up to the shore will slow down the waves and they'll lose their energy, causing the waves to have less oomph.
- Tide - Some spots are totally tide dependant.
Find out what makes the best waves here.
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This Helped so Much thanks
Hi
I also like your description of "How the waves are made". But you miss one important part. That is the difference between hi and low pressure over the sea... That also creates waves.
The differences creates a swell and that is a stronger wave that comes out from that. Depending on how low the low-pressure is and what direction it has, related to where your surf break is, together with wind speed.
It is really obvious when you follow up how waves appears in a limited sea like the Baltic sea. I can follow the wether-forcast and see how the wind waves and how the swell appears. Right in front and on both sides of the low-pressure direction. The wind is not going straight forward as you know. It rotates against the clock direction if it is a low pressure and with the clock direction if it is a Hi pressure. Check the satellite forecast videos.
Cheers
Conny R
Waves come from the wind, and the wind blows strongest when isobars are close together in a low pressure system. High pressures don't tend to have the same wind strength.
The wind direction in a low pressure and high pressure system is the opposite way in the southern hemisphere.
I surf and I like it.
Surfing is a good sport . I a`m 8 years old.I have a little brother and he is 5 and he can stand up.His name is Henrik.Surfing is awesome !!!!!!!!!!!!!!!
Hello!
I have a question. In the picture the wind is blowing over the sea towards the land to create waves. The more wind (lo-pressure-area)the bigger the waves will get. BUT, this site says also that the best wind for surf is an offshore wind!?
Now why is that? Offshore winds blow towards the sea, so in your picture will that stop the wave... or blow them away...
Please help!
A light offshore wind will not be enough to blow the waves away, it ensures that the waves that break are clean and do not close out. If the offshore wind is really strong, it will indeed ruin the waves.
The offshore wind only needs to blow locally, compared to strong winds far off the shore that generates good swells.
Aloha, this has definitely helped me with my science fair project.
i did not get it:P
what about the moon gravitational pull??????????
Gravitational pull does not have an effect on the creation of swell. It only effects the tides.
Gravitational pull may indirectly effect the size and quality of the waves when they reach the shore. Many surf spots are dependent on the tide level.
This should help me get an A on my project.:p
what do the 2 type of numbers mean on a weather map
One is the pressure, one is the wind speed.
yo me name is joe, how are waves formed ;)
what waves do you get at Bells Beach Victoria Australia?? kawabunga
The moon in fact does have an effect, though it may be indirect or minimal. As the planet orbits the sun and the moon the Earth, the moon releases it's gravitational hold on different parts of the Ocean at different times. The rotation of the Earth in turn(with all of it's variously sized land masses and creviced sea-floor topography)causes mild agitation in the hydrological cycle, both on land and at sea. Imagine being able to grab a hand full of water as though it were a bed sheet, when you let go, you'd get massive ripples. Same thing(much bigger scale). Later
Is South Africa's Jeffrey's Bay with offshore winds one of the best surfing spots in the world?
@eddiek: Yes, it's a world class wave.
I always thought that waves were made only by the moon and that surfing would disappear forever when the moon disappear in space forever :3
this is amazing
sir I have a doubt about waves how they are produced I have gone through your website about waves sir still I have a doubt if waves are generated by wind why lakes ponds does not have any waves sir please answer my doubt by giving the reply to my mail id
Hi sushma,
Lakes and ponds do have waves. The reason they are only tiny is that due to a small fetch (see above). That said, there are large lakes that can have surfable waves - like the great lakes in the US/Canada - have a look here at a few Great Lakes surf photos posted on the forum.
These facts are awesome!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Hi, very interesting reading. Im not a surfer, but do enjoy sea kayaking, tending to only venture out in reasonably calm days, i.e not much more than 10 mph winds and reasonably high pressure. If Im reading these comments correctly can I assume that an off shore wind more powerful than this will still pretty much mean a calm sea, smooth to moderate? If so what kind of winds and I assume only in high pressure?
thanks Eddie.
An off shore wind is when the wind blows away from the beach and a onshore wind is when it blows onto the beach. It is normally a lot rougher when is is onshore with a big swell. ;)
Thank you for the information for my research paper.
i don't want the effects of swells i want to know how there made by the way I'm 11 and I know how to surf it's awesome! Did you know apparently you can surf on your stomach? I found out you can it's pretty cool!
How are waves formed patrol,,,please help
i know wind,gravity and earthquake.
i need two more.
this gave me an important presantation on waves for making my project on jpan
I want to know whether surface tension really affecting wave formation.And if so then why?
Swells generated in southern hemisphere can travel northward in Indian ocean
and enters into bay of Bengal without being influenced by coriolos force. I want to know about it
no one cares about waves
a lot if people do
thanks mate
Hi i have nice bike i ride to beach on. I like when the ice cream truck is there. I no not much about swell.
thanks fellow grom