Editing Physical oceanography (section)

=== Temperature ===
The temperature of ocean water varies significantly across different regions and depths. As mentioned, the vast majority of ocean water (around 75%) lies between 0° and 5°C, mostly in the deep ocean, where sunlight does not penetrate. The surface layers, however, experience far greater variability. In polar regions, surface temperatures can drop below freezing, while in tropical and subtropical regions, they may reach up to 35°C. This thermal stratification results in a vertical temperature gradient that divides the ocean into distinct layers.

# '''Surface Mixed Layer''': This uppermost layer is well-mixed due to wind and wave action, resulting in minimal temperature variation with depth. The thickness of this layer varies depending on location and season but can extend from 50 to 200 meters.
# '''Thermocline''': Below the mixed layer lies the thermocline, a zone where temperature decreases rapidly with increasing depth. The thermocline is especially pronounced in tropical and temperate regions but is absent in polar waters where surface temperatures are already near freezing. The depth and sharpness of the thermocline can shift with seasonal changes and ocean currents, playing a critical role in regulating heat exchange between the ocean and the atmosphere.
# '''Abyssal Zone''': Beneath the thermocline is the deep ocean or abyssal zone, where temperatures remain relatively uniform, hovering just above freezing (0°-3°C). This cold, dense water originates from polar regions, where surface water cools, sinks, and spreads towards the equator along the ocean floor, forming the deep ocean circulation system.