What is a swell?

[kyleisanoob12]

Can someone explain what a swell is? I try reading up on Google, but never remember/understand.

[oldmansurfer]

A simpe way to think of it is waves before they break

[IanCaio]

Waves are formed when wind blows through an area (fetch), with some speed for some time. When weak winds blows for a while, wind waves are formed. Like those you see in a lake on a windy day. They are relatively weak and usually the wind that forms them breaks their crests at the same time.
But when high speed winds blows on a large fetch for a while, swells are formed. Those have more energy associated to them and can travel several miles. When they reach really shallow waters (a beach for example) they break, hopefully giving us a good ride

There is a lot to be read about waves, swells and forecast if you are curious, but this is just a really simplified definition of a swell.

[oldmansurfer]

all waves are swells untill they break

[IanCaio]

Sure OMS! Maybe I just made him more confused

Actually, I made a mistake there with the naming. What I meant with "wind waves" are actually those short period waves that are formed with wind, that you can spot on water, foaming on the crest and not really defined. Their crests collapse because of the wind itself, and they are not considered a swell (they can't travel long distances). I guess the right name is ripples.

Something like that:
Ripples


Swells

Sorry about that, I will edit the post

[oldmansurfer]

You never heard of a wind swell? perhaps it is groundswell you are thinking of?

[IanCaio]

They are like swells formed closer to the shore? I don't know, was just trying to make a distinction between a swell and some undeveloped wave caused by a local wind (like those ripples from the image).. Maybe I'm just trippin too far from topic

[IanCaio]

By the way, storm conditions are usually related to wind swells? That would make a lot of sense!

[jaffa1949]

Swells are why people travel to Indonesia and Hawaii in season.

The Indonesian swells are generated by winter southern hemisphere near polar storms ( very deep lows) in the zone around Antarctica and clear up and get organised into long period swell that arrive in Indonesia regardless of local conditions, ( which during late April to October are the most favourable with the tropical dry season and off shore winds dominating)
Similarly the peak Hawaiian swell arrive over the Christmas New year period and originate from Northern hemisphere winter sub polar Aleutian storms.
Other swell generating events are sub tropical lows (Cyclones typhoons, hurricanes same thing different local names).
The longer the distance ( fetch ) the storm winds effect the ocean surface the greater the multiplier of the wind strength generating swell size.
The longer the wave length ( period) of the swell the stronger and larger amount of water is involved in the power of the wave eventually generated at the beach.

The net has allowed distant tracking and fairly good predictive swell forecasts, so the big wave guys can respond to swell windows.
Any size swell will respond differently to the offshore contours ( bathymetry) be refracted, reflected and enhanced or diminished by that and then the final breaking zone changes the swell again into a wave hopefully one which we can ride.

[oldmansurfer]

I think a simple way to differentiate them is when you are looking out for something to ride you are looking for swells, when you takeoff on one it is a wave. There are lots of sources of information but my understanding is that there are short period swells which are wind swells or waves created by near shore wind (this still may means hundreds of miles of wind) and long period swells which when they reach shallow water are called groundswells which are created by storms far away from the shore. Surfers often love the groundswells because the waves are bigger, farther apart and more regularly occurring than wind swell. If you look at the east side of Kauai or other places where the shore is not exposed to huge expanses of ocean where storms can form well off shore then you mostly get windswell or short period swell. I have become used to windswell and I love it but others don't share my love for it.

[kyleisanoob12]

So a swell is a wave before it breaks, and a wave is what you ride (I'm going to call it a broken swell)?

[oldmansurfer]

There are many definitons of swell and wave but as far as a surfer is waves break swells don't so a broken swell is a wave but you wouldn't call it a broken swells since swells don't break.