# Why is sea surface water relatively constant?

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• jaumzaum
In summary, the author of the book on oceanography explains that sea surface water remains relatively constant during the day and changes slowly throughout the year due to the majority of the sun's energy being used for evaporation. This evaporation process cools the water and maintains equilibrium, while also creating a deep current and causing erosion in shallow seas. The author's reasoning is supported by the existence of a deep seafloor valley formed by halocline-driven currents.
jaumzaum
I'm studying oceanography and the author of the book that I'm currently reading stated that sea surface water is relatively constant during the day, changing very slowly during the year. He says "this is because almost all the energy received from the sun is used in the evaporation of water".

I don't fully understand the reasoning of the author, can anyone explain this reasoning for me better?

What's the full quote? Constant what? Temperature? It's because evaporation cools the water, which balances out the heat gain from the sun. Obviously this system would have to seek equilibrium and it would also have a very large thermal reservoir to resist changes.

Lnewqban and davenn
It's best to give us the name of the author and the book. Is he talking about sea level? If water evaporates from the oceans, sea level will drop.

jaumzaum said:
He says "this is because almost all the energy received from the sun is used in the evaporation of water".
Evaporation of water from the sea surface, results in an increasing salt concentration. That makes the remaining water more dense, so it sinks and flows away as a deep current, while lower density wave-mixed seawater flows in on the surface.
https://en.wikipedia.org/wiki/Halocline

Erosion by halocline-driven currents, adjacent to shallow seas, have formed some deep seafloor valleys. There is a 120 km long example here; Google Earth -38.680°, 149.173°.

PeroK and anorlunda

## 1. Why does sea surface water temperature stay relatively constant?

Sea surface water temperature stays relatively constant due to the ocean's large volume and high heat capacity. This means that it takes a lot of energy to change the temperature of the ocean, so it remains stable despite external factors such as air temperature and sunlight.

## 2. How does the ocean maintain a constant salinity level?

The ocean maintains a constant salinity level through various processes such as evaporation, precipitation, and mixing with freshwater from rivers. These processes help balance the amount of salt in the ocean, keeping the salinity level relatively constant.

## 3. What role do ocean currents play in keeping sea surface water constant?

Ocean currents play a crucial role in regulating sea surface water temperature and salinity. They help distribute heat and salt throughout the ocean, creating a balance and preventing drastic changes in surface water conditions.

## 4. How does the Earth's tilt affect the stability of sea surface water?

The Earth's tilt has a minimal effect on the stability of sea surface water. While it does cause seasonal changes in temperature, these changes are relatively small and do not significantly impact the overall stability of the ocean's surface water.

## 5. Can human activities impact the constant state of sea surface water?

Yes, human activities such as pollution and climate change can have a significant impact on the stability of sea surface water. Pollution can introduce harmful substances into the ocean, while climate change can alter ocean currents and temperature, leading to changes in the stability of sea surface water.

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