## Sunday, March 24, 2024

### Oceanic Deep Water Waves in Whole Gale : Whitecaps on a Lake, But Bigger

HGL'S F.B. WRITINGS: He did some answering, though, to others ... · Assorted retorts from yahoo boards and elsewhere: Oceanic Deep Water Waves in Whole Gale : Whitecaps on a Lake, But Bigger

Q
If a whole gale (60mph) occurs on the Pacific Ocean, far from land, what do the waves look like?

Nathan Smith
Thu, 21.III.2024
“If a whole gale (60mph) occurs on the Pacific Ocean, far from land, what do the waves look like?”

That depends on how long the wind blows and how large an area it's blowing over. It also makes a difference how large the ground swells are, and which direction(s) they're from. The new waves generated by the gale will become bigger and more chaotic as they interfere with existing swells.

After a 60 knot gale has blown a day or two there will be what's called a fully developed sea. It's as rough as that amount of wind can get it. A fully developed sea in a 60 knot wind will have waves of many sizes. The largest waves will be over 40 feet or 12 meters high. The crests of some waves will be breaking. The wind strips water off wave crests, so foam and spray will be flying in the air and blowing in streaks on the water surface. The air is full of spray. Sometimes one wave will be extra large, like 60 or 70 feet high due to constructive interference.

The waves look about the same as whitecaps on a lake, but the scale is different. Imagine a pile of water the size of a 4 story building breaking over you. These keep coming every 10 to 15 seconds for something like 30 hours.

[moving image, gif]

Fri, 22.III.2024

Hans-Georg Lundahl
Thank you … what is the distance of the crests or troughs from each other, you only mentioned height, not wavelength.

The picture shows a ship heading into the crest, not how it would look if the motors were off and the ship were facing the crests sideways.

Nathan Smith
The wavelength varies due to the mixture of new waves forming over existing ones. As the sea matures toward full development, the period will be about 10 to 15 seconds or more. The dominant wavelength between crests would be on the order of 300 meters or more. If the wind direction has changed during the gale, or if large swells are passing through the area from elsewhere, the wave heights, and wavelengths, will be very irregular. As the waves propagate away from the storm, they sort themselves out into more regularly spaced swells. The longer swells move faster. Save pass right through each other if they come from different directions or have different lengths. The largest waves in a gale can have 10 seconds periods and lengths of 600 meters or more.

Sat, 23.III.2024

Hans-Georg Lundahl
“The dominant wavelength between crests would be on the order of 300 meters or more.”

“The largest waves in a gale can have 10 seconds periods and lengths of 600 meters or more.”

Thank you very much!

What I had expected, but better. What I didn’t expect directly, but which is not suspect either is:

“The wavelength varies due to the mixture of new waves forming over existing ones.”

Does it vary SO much that it can resemble the turbulence of coastal waves?

Tue 26.III.2024

Nathan Smith
The sea is very confused and chaotic while the storm wind is blowing and building new waves. It looks like this. The sailboat is Gypsy Moth lV off Cape Horn. Sir Francis Chichester was sailing it alone around the world.

Waves start forming as ripples about an inch or a few centimeters in size. From there they keep getting bigger, oscillating on the water surface of the larger waves already present. Waves of every size can coexist together. Smooth, regular swells are only seen a few days later after the storm waves have propagated away from the gale a few hundred miles, or a few thousand, to an area of calmer wind.

Hans-Georg Lundahl
All of these far from land?

“The sailboat is Gypsy Moth lV off Cape Horn.”

1. The fact is, I am trying to figure out what waves around the Ark would have been like over a global ocean — is it sufficiently far from land to be deep and comparable?
2. At least all of the three seem to involve no very steep waves, like the turbulence near a coast?

Nathan Smith
All the photos are of conditions in deep water, many miles from shore.

If waves get steep they break. Waves on a beach break as it gets shallow near shore. That's “surf”. In deep water, as the wind is building up waves, they get steep and break. Those are “whitecaps”. They can be any size. They are steep up near the crest. Rogue waves can be very steep and dangerous even if the water is 3 miles deep in the middle of an ocean.

I suggest looking on you tube. There are videos made by people on ships in storms.

Hans-Georg Lundahl
Thank you.

What I have seen so far from videos, they are typically taken with ships heading into the waves, which makes for more turbulence. The Ark had no motor, as far as we know, and no sails.

Rogue waves are certainly likely to rock any vessel on the deep, but they are also relatively isolated, right?

Nathan Smith
They are infrequent, but in storms they do happen. Some happen in normal weather when big swells from different directions meet a current.

The helmsmen on those ships in the videos are heading into the storm waves to save their lives. If they get broadside to waves like that, it's possible to get rolled over. Losing power or rudder control out there presents a dangerous problem. A drifting ship tends to lay in the troughs ( crosswise to the waves ). So the ship rolls badly. That can end tragically whenever an extra steep and extra high wave happens to break against the side of the ship.

Hans-Georg Lundahl
“A drifting ship tends to lay in the troughs (crosswise to the waves ). So the ship rolls badly.”

The rolling period of the Ark was about 12 seconds.

I have the impression all of these ships are smaller than it?

“whenever an extra steep and extra high wave happens to break against the side of the ship.”

That’s sth which God’s providence would have avoided, obviously.