What primarily drives surface currents in the oceans?

What primarily drives surface currents in the oceans?

• A. Wind
• B. Tides
• C. Gravity
• D. Coriolis effect

Answer: (A)

Wind is the main force that sets surface currents in motion. When wind blows across the ocean, friction transfers some of its momentum to the water, creating a moving layer at the surface. Because the Earth rotates, that moving water is deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, shaping large, circular gyres. Tides, driven by the Moon and Sun’s gravity, mainly cause vertical movement and shorter, coastal flows rather than the sustained, basin-wide surface currents. Gravity underlies the weight of water and pressure differences, but it isn’t the energy source for these horizontal, long-lasting currents; the wind is.

Wind is the main force that sets surface currents in motion. When wind blows across the ocean, friction transfers some of its momentum to the water, creating a moving layer at the surface. Because the Earth rotates, that moving water is deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, shaping large, circular gyres. Tides, driven by the Moon and Sun’s gravity, mainly cause vertical movement and shorter, coastal flows rather than the sustained, basin-wide surface currents. Gravity underlies the weight of water and pressure differences, but it isn’t the energy source for these horizontal, long-lasting currents; the wind is.