World Climate and Climate Change | Class 11 Geography Notes

Temperature of Ocean Waters

Ocean water temperature varies both horizontally and vertically due to factors such as latitude, depth, season, and ocean currents. Solar energy heats ocean surfaces, but the heating and cooling processes are slower compared to land due to water's high specific heat capacity. The temperature of surface water decreases from the equator towards the poles because of decreasing solar insolation. Unequal distribution of land and water, prevailing winds, and ocean currents also influence temperature distribution. For example, warm currents like the Gulf Stream raise temperatures in cold areas, while cold currents like the Labrador Current lower temperatures in warm regions. Vertically, ocean temperature decreases with depth, with a boundary layer called the thermocline marking a rapid temperature drop between surface warm water and cold deep water. In tropical regions, the ocean can be divided into three thermal layers: a warm surface layer about 500 m thick, a thermocline layer with rapid temperature decrease, and a cold deep layer. In polar regions, surface temperatures are near 0°C and temperature changes little with depth.

📊 Diagram: Figure 12.3: Thermocline; Figure 12.4: Spatial pattern of surface temperature (C) of the oceans

🧪 Activity: Observe temperature variation with depth in ocean water samples or simulated models.

🔗 Connection: Following temperature, the chapter discusses salinity of ocean waters and its distribution.