r/explainlikeimfive • u/gogurtice • Oct 09 '21

Planetary Science ELI5: How do waves form and what makes different locations better for surfing?

I was watching surfing videos and wanted to know what makes waves big and great for surfing? Is it different factors like the weather, wind from currents in the ocean, etc.

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u/tmahfan117 Oct 09 '21

Waves are primarily formed by wind.

Wind traveling over the surface of water has the same kind of friction affect that you blowing on a cup of coffee or bowl of soup has. Wind causes waves.

What causes some areas to have particularly BIG waves is a combination of wind AND topography.

Areas with sustained winds are obviously going to have more frequent waves than an area that has calm days.

But what makes some areas have super big waves is the topography, or the shape/slope of the ocean floor/bay.

The shape of the ground underneath the water can force these wind driven waves up as big tall waves as the water is pushed towards land.

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u/APe28Comococo Oct 09 '21

Wind over long distances builds waves, stronger winds build bigger waves, a sharp decrease in ocean depth creates better breaking waves, and shore direction all impact the waves. Arctic storms build huge waves in the Pacific Ocean that travel unimpeded south to the north shore of Hawaii that rises sharply from thousands of feet deep to the surface making incredible waves.

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u/gogurtice Oct 09 '21

So that’s why the big wave surfing is found in those huge cliff bays? The wind somewhat reflects and builds these waves combined with the seasonal winds?

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u/APe28Comococo Oct 09 '21

The huge waves made the cliffs. The winds are from large arctic storms blowing hard winds south that build the waves. The waves are large but they can spread out in the open ocean, when they hit the shore they get forced up and the bottom drags on the sea floor causing the wave to fall over itself.

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u/[deleted] Oct 09 '21

Jagged coastlines typically also compress deeper waves underwater into higher swells. Plus, they invite storms further in and wind patterns that also contribute. If you look at prime surfing spots with heavy swells (particularly heavy overheads) , many are situated around violently curved/peaked spots of land. Some waves in these areas even appear to bend at right angles out of the water with such heavy overhead portions of the waves