Have you seen viral images of seas that seemingly don't mix, like the North Sea and the South Sea? These images often show a distinct line separating two bodies of water. While visually striking, this phenomenon isn't due to some mysterious oceanic force. The primary reason for this separation is the meeting of river estuaries with the ocean.
Chemist Vladimir Sánchez, also known as @breakingvlad, explains that the 'brown sea' and 'blue sea' separation occurs where a river flows into the ocean. The river carries sediments that, upon contact with saltwater, remain suspended, creating a visible boundary. These areas are commonly known as estuaries.
The Science Behind the Visuals
This phenomenon is common in areas with strong marine currents. The differing densities, temperatures, and suspended materials of the river and sea water create a temporary visual border. Over time, these suspended particles separate, similar to how sediments settle in a tube of water, eventually clarifying the liquid. While a distinct line might be visible, the waters do eventually mix, although the process can be slow.
The idea that oceans don't mix is a myth based on real scientific principles. Factors such as salinity, temperature, water density, and ocean currents create noticeable boundaries where different bodies of water meet, giving the illusion of separation. However, deep ocean currents and thermohaline circulation gradually blend these waters over time.