Question

After how much depth the temperature of sea water is uniform?
A) 1000 m
B) 1500 m
C) 2000 m
D) 2500 m

Answer 1

Hint:
The surface temperature of the seawater is a function of two factors. These are latitude and season. At a little depth, the temperature remains uniform. The average temperature of seawater recorded at 5000 meters is \[1{}^\circ C\] only.

Complete Answer:
It is known that water gets heated and cooled at a slow rate. The seawater stays in continuous motion and this results in variation of temperature of the surface of the water in different periods. The mixing of seawater due to waves and currents also impacts the temperature of the water. With an increase in depth the temperature of water decreases. Moving from the equator to the Polar regions, the temperature of seawater decreases. The average surface temperature of seawater in the equatorial region is \[27{}^\circ C-28{}^\circ C\]. The temperature reaches the freezing point in the polar areas. In the polar seas located at \[60{}^\circ \] latitude, the surface water remains permanently frozen.
There is a prominent decrease in the temperature of seawater at certain depths. With little depth, the temperature is seen to be more or less uniform. But with increasing depth, the temperature falls almost to \[1{}^\circ C\]. At 200 meters depth, the average temperature is \[12{}^\circ C\]. The temperature at 2000 meters is uniform everywhere. It is around \[3.5{}^\circ C\] to \[4{}^\circ \text{ }C\].

Therefore, we can conclude that the right answer is option C.

Note:
Water has an extreme heat capacity. Due to this, the heat is mixed downward in summer surface heating conditions. During winter surface cooling the heat mixes upward. This heat transfer helps in reducing the actual change in sea surface temperatures during annual cycles.