Why do waves always seem to go towards the shore?

[Knothead]

Air tends to rise over land as the land is generally hotter than the ocean. Air tends to drop over the ocean as it cools down again. So there is a permanent cycle of cool air blowing in from the sea, to be heated over land, to rise, to circulate back over the sea again.

 

Waves are formed through wind action. The ocean wind generally blows from the cold ocean to the warm land, forming waves which looks as if they're always aiming for the land.

 

It all depends on the specific local weather system. You can even find waves running parallel to the shore if the wind conditions are such. What I wrote above was merely a generalisation.

 

This is called a sea breeze and a land breeze.

 

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1903/es1903page01.cfm

 

I can tell you that in open waters, the waves go which ever way the wind is blowing. Sometimes they go whichever way the wind was blowing yesterday and the day before at the same time. Meaning that they come from different directions. Boy is that uncomfortable.

[phision]

 

I can tell you that in open waters, the waves go which ever way the wind is blowing. Sometimes they go whichever way the wind was blowing yesterday and the day before at the same time. Meaning that they come from different directions. Boy is that uncomfortable.

 

Regardless of which way the wind blows, the waves are created at the surface of water and travel from there to the boundary of the water which is the shore. See #17 .

[esbo]

Why do waves always seem to go towards the shore?

 

Ocean surface wave are generated on the surface of the water and propegate away from their origin(where they are created) until they reach the boundary of the body of water i.e. the shore, hence "always seem to go towards the shore".

 

 

I tend to agree with this!!

I was puzzled by this somewhat, one thing which crossed my mind was that winds tend to be usually onshore, but

I amd pretty sure this is not always the case.

 

Certainly you would not expect a big wave to start off from the shore because they take time to build up.

Waves of course tend to go outward from there point of origin and there is no real point of origin for

a wave on the shore.

Every thing that move in the sea will generate outward waves, ie fish, ships, whales!!!

They all radiate outwards and will even go through each other, but ultimately always end up on the shore.

 

 

I think even if you have a strong off shore breeze that will generate mini-outwards waves, but they will

be small beans compared to the cumulative incoming waves.

What I think will happen is this case is you get a more 'choppy effect'.

 

It's an interesting question, one of those things you never really think about but just take for granted!!

[labelwench]

An interesting dialogue on wave action.

 

For a number of years, I lived close to Atlin Lake, B.C., which is a natural freshwater lake approximately 4 miles wide and 85 miles long, situated between mountains. Yes, the waves are always lapping at the shore, save on one of those very rare days of dead calm when the lake will be as flat and reflective as a mirror.

 

No wind, no waves, on inland lakes.

 

The wind is influenced by the mountains and the long narrow lake can really kick up if a North/South wind starts to blow. At such times the big waves are NOT headed to shore, though one will get cross waves heading in from where the big waves meet interference from natural promontories. I distinctly recall one crossing from my youth with our family of six and all of our gear piled into a 16 foot runabout with a 10HP kicker. We were headed across to the town of Atlin, a bit of a diagonal crossing from Atlin River to the town. With such a load, we had about 4 inches of free-board. We were mid-lake, two miles from either shore when the wind picked up hard and fast and the waves threatened to swamp us if we held our course.

 

We angled our course so that we were running in the trough between each wave, which made for a lot of side to side motion but reduced the risk of being swamped, as long as we had power and moved with the waves. We made landfall several miles above the town, having been carried that far off course by the need to work with the energy of the wind and waves. We spent the night huddled on the beach under sleeping bags, unable to light a fire even with gasoline to aid us.

 

The winds reached just over 100 MPH later that night.

 

Edited May 9, 2012 by Under the Rose

[Lancewen]

I'm surprised no one mentioned a tsunami. When a tsunami is generated it creates a wave that resembles rings spreading out similar to what happens when you toss a stone into a pond. So eventually those waves will contact land. I watched a program that showed what happened when a tsunami passed an island. Very nice wrap around effect causing problems on the backside of the island. I don't remember the stated reason for this, but think it happens because a tsunami is a very long powerful wave.

[Village Idiot]

When seen from a beach, the most noticeable waves are the ones close by and that have had time to build up in size. There might also be waves going away from the shore but they would be so young as to be invisible. Crest-to-trough measurements might be so microscopic that the water could look like plate-glass.

[OMICSGroup]

wave go to the shore more or less because its the only place a wave can go to...

waves travel in all directions even though it seems it going in only one..

the wind plays a major role in how waves are created.

as does the moon..

 

example for you to try..

drop a pebble in a pond..watch how the waves are formed and which direction they go..

its more or less the same on a planet scale.. just hard to see it unless u are higher in orbit of the earth

[katsisco]

isn't it something like the fact that the land is heated and the water is cold? Sort of like the reason why the desert is cold at night because the heat loss isn't stopped by the cloud cover?

[BrahmDevPandey]

@CraigD

On 1/30/2007 at 12:11 AM, CraigD said:

Waves do behave this way – if you observe waves crests traveling from deep to shallow water, such as over a sand bar, or in one of the special “water table” apparatuses found in many science classrooms, you’ll see them change direction as you describe – and this is part of the answer. However, this explanation alone can’t fully explain why waves near the shore usually move toward the shore.

 

Here’s a hint. Begin with the assumption that air blown over the surface of a smooth body of water will cause waves that travel in the direction of the blown air (you can experimentally test this with a fan and a basin of water). Note that, once started, waves continue after the wind stops, or even if it blow briefly in the opposite direction. Now, consider what happens when a wind blows over a small area of the surface of the water, while another wind blows at the same speed in the opposite direction over a larger area. Finally, assuming ocean winds blow in random, changing directions. What is the likelihood that such conditions will produce waves moving away from the shore, vs. the likelihood that they’ll cause waves moving toward it? (especially accounting for waves traveling more parallel to than toward the shore changing direction due to refraction)

Sir, please give the full explanation now. I searched for the right explanation here and there, but couldn't find a satisfactory answer. Please explain the full reason as to why do the waves move towards the shore???

[atomsmasher]

I believe waves are created by the flow of air across the water creating high and low pressure points and when the distance between the surface and the ocean bottom is abruptly shortened. 

 

[OceanBreeze]

On 5/9/2021 at 10:52 AM, atomsmasher said:

I believe waves are created by the flow of air across the water creating high and low pressure points and when the distance between the surface and the ocean bottom is abruptly shortened. 

 

“when the distance between the (water) surface and the ocean bottom is abruptly shortened”

That is basically correct; the waves become refracted (bent towards the shore) as they leave deeper water, where they can travel faster, and enter shallower water, where the bottom surface under the water acts as a drag to slow the wave down.

The question becomes much more interesting when you consider the shore on a circular island.

The water waves are slowed and refracted as they enter the shallower zone near the shore and the refraction continues all the way around the island.

The result is that a wave that is travelling from West to East refracts all the way around the Island so that on the East side of the island the waves close to the shore are moving from East to West, towards the shore!

This image demonstrates this effect:

 

And here is a link that likely explains it better than I just did.

But note that for this to happen the island must have a uniformly sloping shore all the way around. There are islands that have abrupt cliffs in some places and in those places the waves may be moving away from the shore. In the movie Papillon, that is supposedly how Henri Charrière escaped, by riding waves moving away from the steeply rising shore on Devil’s Island.

 

(In reality, though, his book and movie is a fiction and there is no evidence that he was ever on Devil’s Island)

 

 

 

 

 

 

 

[balagna]

I do not think that always waves seemed to go towards shore. 

the exact cause (in my opinion) is that the direction (or place) of productor/stimuli/creator of wave.

I also observed this as below. 

simply, if the productor of wave is from the top of surface , then the waves are going towards shore

but, if the productor /stimuli is under of the ground (i.e. surface) the the direction is vice versa.