Question

When you move into the ocean what thermal layers would you encounter? Why the temperature varies with depth?

Answer 1

The temperature structure of oceans over middle and low latitudes can be described as a three-layer system from surface to the bottom.

• The first layer represents the top layer of warm oceanic water and it is about 500m thick with temperatures ranging between 20° C and 25° C. This layer, within the tropical region, is present throughout the year but in mid-latitudes, it develops only during summer.
• The second layer called the thermocline layer lies below the first layer and is characterized by a rapid decrease in temperature with increasing depth. The thermocline is 500-1,000 m thick.
• The third layer is very cold and extends up to the deep ocean floor. In the Arctic and Antarctic circles, the surface water temperatures are close to 0° C and so the temperature variation with the depth is very slight.