Final answer:
The water flow in the Strait of Gibraltar is influenced by salinity differences, tidal forces, and geological factors, which create a two-layer flow system with dense water flowing out beneath less dense water flowing in.
Step-by-step explanation:
The mystery of the Strait of Gibraltar involves water flowing into the Mediterranean Sea without an apparent equal flow outward. This phenomenon can be explained by a combination of factors including salinity differences, tidal forces, atmospheric pressure, and geological factors. The Mediterranean Sea has higher salinity compared to the Atlantic Ocean, causing denser water to flow beneath the less dense incoming water from the Atlantic. This process is known as estuarine circulation. Tidal forces further contribute to the exchange of water by creating tidal bulges that move water in various directions.
Atmospheric pressure is unlikely to cause irregular water flow between bodies of water. The geological structure of the strait, being narrow and shallow, also limits the water flow, facilitating the creation of two layers of different salinity and densities that may appear as a one-way flow. The process is complex and involves the interaction of several physical principles.