Ocean Currents

[OceanBreeze]

I could have sworn I saw a thread here about ocean currents and made a mental note to myself to post a reply. I must have imagined it!

 

 

Ocean currents are very complex, involving the tides, winds, thermohaline circulation and all of these are variable, including seasonal changes but I am not familiar with any “centrifugal force” theory of ocean currents, that I imagined I saw. :lol: 

 

 Anyway, if anyone is interested this is an excellent source of information.

 

 

 

[DrKrettin]

Awesome. Somebody recently mentioned that Coriolis forces were significant.

[exchemist]

Awesome. Somebody recently mentioned that Coriolis forces were significant.

I mentioned that I thought they would be, on the basis that they are for winds.

 

This Russian post and poster seem to have vanished. Perhaps it was a drive-by by the FSB. :) 

[OceanBreeze]

Awesome. Somebody recently mentioned that Coriolis forces were significant.

 

 

The incoming energy from the sun is what powers the winds, and the rotation of the earth, acting via the Coriolis force, sets up the general circulation pattern of wind flow. In the Northern Hemisphere, warm air rising at the equator and flowing northward is turned to the Right (Eastward) by the Coriolis force. At about 30° latitude this warm moist air comes down and returns to the equator in an Westerly stream known as the Trade Winds.

 

 

The winds drag on the water’s surface via friction, this causes water currents to move in the same general direction as the wind blows. These major gyres of ocean-circling currents occur both North and South of the equator. So, it is correct to say the Coriolis effect results in the general direction of circulating water currents, just as it does for the wind.

 

 

The Coriolis doesn’t have any effect on wind velocity; that is determined mainly by differences in barometric pressure, which also has a large effect on water levels. Hence, water level and water currents are significantly affected by both barometric pressure and the direction and duration of the winds.

 

I don’t know what point the original poster was trying to make, as I only had the opportunity to briefly skim through his rather long post. If I recall correctly, he felt that centrifugal force was a major determining factor in seasonal water levels, and then he posted a lot of data pertaining mainly to coastlines, not ocean currents. It seems to me he was conflating tides with ocean currents. It is well established that coastlines do undergo seasonal cycles in their tides due to several obvious facts; the difference between summer and winter water and air temperatures, the amount of precipitation and runoff, and seasonal changes in wind speed and direction.

Because of many variables and complexity, not everything is known about tides and ocean currents, but I see nothing to be gained from a dubious claim about centrifugal forces.

 

Edited January 11, 2017 by OceanBreeze

[exchemist]

The incoming energy from the sun is what powers the winds, and the rotation of the earth, acting via the Coriolis force, sets up the general circulation pattern of wind flow. In the Northern Hemisphere, warm air rising at the equator and flowing northward is turned to the Right (Westward) by the Coriolis force. At about 30° latitude this warm moist air comes down and returns to the equator in an Easterly stream known as the Trade Winds.

 

 

The winds drag on the water’s surface via friction, this causes water currents to move in the same general direction as the wind blows. These major gyres of ocean-circling currents occur both North and South of the equator. So, it is correct to say the Coriolis effect results in the general direction of circulating water currents, just as it does for the wind.

 

 

The Coriolis doesn’t have any effect on wind velocity; that is determined mainly by differences in barometric pressure, which also has a large effect on water levels. Hence, water level and water currents are significantly affected by both barometric pressure and the direction and duration of the winds.

 

I don’t know what point the original poster was trying to make, as I only had the opportunity to briefly skim through his rather long post. If I recall correctly, he felt that centrifugal force was a major determining factor in seasonal water levels, and then he posted a lot of data pertaining mainly to coastlines, not ocean currents. It seems to me he was conflating tides with ocean currents. It is well established that coastlines do undergo seasonal cycles in their tides due to several obvious facts; the difference between summer and winter water and air temperatures, the amount of precipitation and runoff, and seasonal changes in wind speed and direction.

Because of many variables and complexity, not everything is known about tides and ocean currents, but I see nothing to be gained from a dubious claim about centrifugal forces.

 

Fair enough, but I was thinking Coriolis forces would be expected to have a direct effect on the direction of circulation of water currents as well. Any body of water in the N hemisphere moving South towards the Equator or North away from it would be deflected such as to set up a clockwise circulation, wouldn't it? Or is the motion of water currents considered to be too slow for this to have any impact?

[OceanBreeze]

Fair enough, but I was thinking Coriolis forces would be expected to have a direct effect on the direction of circulation of water currents as well. Any body of water in the N hemisphere moving South towards the Equator or North away from it would be deflected such as to set up a clockwise circulation, wouldn't it? Or is the motion of water currents considered to be too slow for this to have any impact?

 

Yes, there would be a direct effect if the body of water was flowing North-South to begin with. But the largest effect is from the winds which do blow North-South due to atmospheric conditions.

[Pauldee094]

Ocean currents are mainly controlled by the mean of Salinity, temperature, and wind. They have a very large impact over a large area, and they are not controlled by the gravity of sun and moon as like tidal waves. Essay writing service is providing the essay writing help for the students of USA.

Edited August 6, 2018 by Pauldee094

[A-wal]

I heard that they mirror the high altitude winds, like the jet stream and that you get get from Asia to the Americas in a boat without even bothering to sail or anything.

 

It makes me wonder why historians are so sure that the continents were isolated from each other before Columbus when it would have been so damn easy to travel between them and roman and viking stuff has been found in America.

 

Egypt had proper big boats but apparently they didn't use them to go anywhere, huh?

 

The winds drag on the water’s surface via friction, this causes water currents to move in the same general direction as the wind blows.

The ocean currents are caused by wind rather than both having a common cause? That sounds ridiculous! How could relatively weak and inconsistent wind on the surface of the ocean produce a powerful and sustained current?

[OceanBreeze]

 

The ocean currents are caused by wind rather than both having a common cause? That sounds ridiculous! How could relatively weak and inconsistent wind on the surface of the ocean produce a powerful and sustained current?

 

It may sound ridiculous to you, but it is a fact that the ocean currents that people are most interested in, especially mariners, are the surface currents and these currents are directly caused by winds, as I said.

 

You can read up on it here  and many other places on the Internet, and maybe after you learn something, it won’t sound so ridiculous to you. But then again, in your case, maybe not. I could not care less what you think anyway.

 

If anyone else is interested, from the link:

 

"Winds blowing on the surface of the ocean push the water. Friction is the coupling between the wind and the water's surface. A wind blowing for 10 hours across the ocean will cause the surface waters to flow at about 2% of the wind speed. Water will pile up in the direction the wind is blowing.

Wind blowing on the surface of the ocean has the greatest effect on the surface. However, for the lower layers of the ocean to move they must be pushed by the friction between the layers of water above. Consequently, the lower layer moves slower than the layer above. With each successive layer down in the water column the speed is reduce. This leads to the spiral affect seen in the diagram. (below)"