PADI Divemaster Certification Practice Exam

What influences large global currents in the ocean?

1. Temperature variations

2. Predominating surface winds

3. Human activities

4. Salinity levels

The correct answer is: Predominating surface winds

Large global currents in the ocean are primarily influenced by predominating surface winds. These winds, which are driven by the uneven heating of the Earth by the sun and the rotation of the planet, create friction on the ocean's surface. This friction causes water to move in the direction the wind blows, forming major ocean currents. In the context of these currents, winds such as the Trade Winds and the Westerlies play a pivotal role. These winds drive the surface waters in specific patterns, leading to the formation of large gyres in the oceans. For instance, the Trade Winds push warm water towards the west in the tropics, while the Westerlies affect the flow of surface water in the mid-latitudes. While temperature variations, human activities, and salinity levels can also affect ocean behavior, they do not directly create the large-scale currents like surface winds do. Temperature can influence water density and local current patterns, human activities can impact local waters but not the vast oceanic systems, and salinity levels can affect density and stratification but are secondary to the influence of prevailing winds. Therefore, understanding the role of prevailing surface winds is crucial for grasping how large global currents operate within the ocean.