# What is the impact of storms on submarines?

Tags:
1. May 28, 2017

### peevemagpie

I have not really read anything about the topic until this time. But this is interesting for me. I have to read more on it or is there a video related to this topic?

2. Jun 13, 2017

### TheOldFart

Picture the ocean as the atmosphere but with more momentum and able to store even more heat energy.

It really is constantly changing, constantly in motion, and there are storms and gales and the occasional calm day.

There are flows of fresh/less salty water from rivers and melting icebergs and ice sheets, great torrents from undersea vents and volcanoes, thermals as powerful as the ones that sailplanes ride in the atmosphere.

I think it'd be a mistake to picture the ocean as this placid bathtub with just some churn on top. I think a better picture is the movement of moisture and wind that you see in the air...just wetter and below the waves.

There are small organisms (can't remember what kind, can't find my cite either) that are genetically identical at both poles. They apparently ride the conveyor currents from one pole to the other in water that stays cold enough for them to survive.

http://www.whoi.edu/main/topic/currents--gyres-eddies

3. Jun 22, 2017

### msubby

The depth the effect of a wave will be felt when inside a submarine is equal to 1/2 the wave length of the wave on the surface. IE if the peak to peak distance of the wave at the surface is 100m, the effect of that wave will be felt down to 50m depth. The wave form of a 'wave' as in as found on the open ocean, is sinusoidal. Therefore the form (shape) of the effective wave beneath the ocean is the lower half of a standard sinusoidal waveform. The bulk of the volume of that wave form is closer to its base line, in this case the surface of the ocean. Therefore the bulk of the energy contained within it is greater, closer to the surface. So in simple terms, the deeper you go, the less effect the wave will have until you reach the 1/2 wave length depth, when there ceases to be any effect. Incidentally, the effect felt is that the submarine surges back & forth with each passing wave.

4. Jun 23, 2017

### olivermsun

The 1/2 wavelength rule is a good way to think about the physics of the surface waves and their decay with depth. To answer the question of whether the waves will be "felt" inside the submarine (or whether the boat will be significantly affected), one probably also needs to consider the wave amplitude and period, as well as any compounding conditions such as mixed waves, shears, etc.

FWIW, this is usually a decent approximation, but you commonly see some "peakiness" to the waves as the amplitudes get larger.

Last edited: Jun 23, 2017
5. Jun 23, 2017

### msubby

The inferred query in the original question seemed to be, was the effect of a wave (or wave system) a surface phenomenon or full water column depth phenomenon. The two instances given, being during a hurricane or a Tsunami. The two examples being perfect examples of each event. The Tsunami is a full water column movement (transfer of energy) & a hurricane is a surface movement governed by the sinusoidal rule (with small variations due to mixed wave patterns etc).

6. Jun 23, 2017

### olivermsun

The tsunami is a shallow water wave, defined as a wave whose wavelength is significantly longer than the depth of the ocean, so yes, its motion is not significantly attenuated at depth (as seen from the 1/2 wavelength rule you mentioned in your post).

I'm not sure what you mean by a hurricane being a sinusoidal surface movement. A hurricane is a storm. The seas generated by a hurricane can potentially be felt far from the surface, certainly at depths where a sub can be operating (as mentioned in at least one post earlier in this thread).

7. Jun 23, 2017

### msubby

What I was saying was the wave type induced by a hurricane is a sinusoidal waveform, at the surface. The effect of that waveform is felt down as far as 1/2 the distance between peaks of the wave form at the surface.

A wave isn't a single waveform in reality. It is a composite pattern of waveforms overlaid upon each other. Hence the occasional larger than average wave often observed, when the peak of two or more overlaid waveforms synchronize at one location.

A wave form in the open sea can have a peak to peak distance of hundreds of meters. A good example is the long rolling swell, which isn't normally considered to be a wave. But it is. It is these long swells which produce the deepest effects in the water column. (Dis-regarding Tsunamis for now)

I am a submariner, in mini subs. I have spent thousands of hours in the zone where the effects of the waves above can be felt. The long rolling swells, often seen pushed in front of large weather patterns, penetrate the deepest. The short sharp waves caused by local wind conditions don't penetrate very far at all.

8. Jun 23, 2017

### olivermsun

We view the waves induced by a hurricane as a superposition of sinusoidal waveforms as a matter of convenience. As I mentioned earlier, deep water waves aren't exactly a superposition of independent sinusoidal waves, but it is an approximation that works very well in many cases.