<p>Salinity and temperature both affects the density of sea water. When water with a fixed salinity cools down, it becomes heavier and sinks. In the same way, when vapor or ice removes water from sea water, the remains is more saline and heavier. 
Thermohaline circulation can work as you describe. Surface water in the tropics is saline, due to evaporation, but warm due to high temperature in the atmosphere and therefor low density. As it reach colder climate (less solar energy per area), it cools down and the high salinity makes it sink. Surface water in polar regions also get heavier as ice is formed of water and leave the salt behind in the sea. </p>

<p>This is very simplified model, you can read more on the topic <a href="http://oceanmotion.org/html/background/ocean-conveyor-belt.htm">here</a> and <a href="http://oceanservice.noaa.gov/education/tutorial_currents/05conveyor1.html">here</a>.</p>

CC BY-SA 3.0
2015-03-29T23:35:03.113Z
2015-03-29T23:35:03.113Z
user2821
<p>I'm slightly confused by how thermohaline circulation works in the Earth's oceans. Is it different  for surface water as opposed to deep water? I thought that warm water from the equator is transported to the poles, cools down, and then returns to lower latitudes. Is my thinking incorrect? Isn't water denser near the equator because of higher salinity? How does this impact the ocean circulation? </p>

<p>Thanks!</p>

<ocean><thermohaline-circulation><salinity>
Thermohaline Circulation in the Oceans
Shan
# Thermohaline Circulation in the Oceans

(Asked by: username_0 on 2015-03-29)

I'm slightly confused by how thermohaline circulation works in the Earth's oceans. Is it different for surface water as opposed to deep water? I thought that warm water from the equator is transported to the poles, cools down, and then returns to lower latitudes. Is my thinking incorrect? Isn't water denser near the equator because of higher salinity? How does this impact the ocean circulation?

Thanks!

**Tags:** ocean, thermohaline-circulation, salinity


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## 1 answers

### Answer by username_1 on 2015-03-29. Score: 9 | Accepted answer

Salinity and temperature both affects the density of sea water. When water with a fixed salinity cools down, it becomes heavier and sinks. In the same way, when vapor or ice removes water from sea water, the remains is more saline and heavier.
Thermohaline circulation can work as you describe. Surface water in the tropics is saline, due to evaporation, but warm due to high temperature in the atmosphere and therefor low density. As it reach colder climate (less solar energy per area), it cools down and the high salinity makes it sink. Surface water in polar regions also get heavier as ice is formed of water and leave the salt behind in the sea.

This is very simplified model, you can read more on the topic [here](http://oceanmotion.org/html/background/ocean-conveyor-belt.htm) and [here](http://oceanservice.noaa.gov/education/tutorial_currents/05conveyor1.html).


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