Why does sound travel so far over water?

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Why does sound travel so far over water?

In: Physics

2 reasons.

1) sound travels with “pushing” energy. If you’re in a forest, all those pushes hit the trees and get absorbed, so the sound doesn’t travel as far before it gets all absorbed. There’s nothing to absorb it over water, just flat open ocean.

2) for the same reason as above water has stronger winds above it and those winds can grab the sound and push it even further.

Great question!

First, we have to start with what sound IS to understand how it travels. Sound is essentially a wave. When you drop a pebble in perfectly calm water, you see waves coming off the point, right? That’s a lot like sound. When you snap your fingers, you are “rippling” the air, which travels to your ear drum. Your ear converts the ripples into signals that go to your brain.

If sound is a wave that goes through the air, then we also know what can interrupt that wave. Standing in a room, the wave will bounce off anything in the room as well as the walls, floor, and ceiling. Depending on the shape of the object and the material, it’ll reflect different amounts of the wave. In some cases, it’s absorbing the wave! Shouting across a field is difficult because of all the irregular objects on the ground scattering and/or absorbing that air wave (grass, rocks, etc…).

Water reflects air pretty easily because it’s a lot more dense than air. For all intents and purposes, we can think of water as being a very hard, smooth, surface. A lot of the air is allowed to move very easily across that surface and therefore the wave travels much farther.

There are a lot of other factors too, like wind. Because sound is really just a wave traveling through air, wind can jumble it up and take it really far away. Lakes also tend to have banks, which reflect the air back over the water, so it keeps the sound channeled onto the lake.

At the end of the day, think about sound as a wave that radiates from a source. You hear that wave and all the reflections of that wave from everything around you.

eli5 and over water eh. Air over the water is much cooler than air 30′,40′,50’… above the water. Sound refracts/reflects(?) back down and across the water instead of crossing these layers and fading away. It’s akin to talking into a pipe only that pipe is as wide as a lake.

Water is super smooth and super flat, even with waves it’s nothing like hills or forests on land. The shape of trees is really excellent at absorbing sound. The advantage of water is that it doesn’t absorb sound well and the super flatness prevents the sound from distorting as much.

The surface of water will actually work to absorb sound to some degree. However, far out from shore there are a lack of any other physical objects such as trees, bushes, grass, buildings, soil, etc. So there isn’t much to *block* sound from traveling.