Spinning Currents: Coriolis Effect in Oceans Quiz

The Coriolis parameter is calculated based on the sine of the latitude. This means the effect is maximum at the poles and vanishes at the equator. This is why hurricanes cannot form on the equator as there is no rotational force to start the spin.

In the Northern Hemisphere deflection is always to the right. In the Southern Hemisphere it is to the left. This reversal is crucial for understanding why ocean gyres rotate in opposite directions in different hemispheres.

Named after Vagn Walfrid Ekman this model shows that each successive layer of water is moved by the layer above it but is further deflected by the Coriolis Effect and slowed by friction.

While the very top layer of water moves at a 45 degree angle to the wind the average movement of the entire Ekman layer which is the top 100 meters is exactly 90 degrees to the wind.

If wind pushes surface water away from the coast 90 degrees to the right of the wind in the Northern Hemisphere deeper colder water must rise to replace it. This process brings life-sustaining nutrients to the surface.

In the center of ocean gyres water piles up into a hill. Gravity wants the water to flow down while Coriolis pushes it back. When these balance the water flows in a steady circle around the hill.

At the base of the Ekman Spiral usually around 100 meters the energy from the wind has been so deflected and dissipated that the water moves 180 degrees opposite to the wind. Beyond this depth wind has virtually no direct impact.

The Coriolis force is a product of the objects velocity and the Earths rotation rate. Therefore the faster a current moves and the further it is from the equator the stronger the apparent curving force becomes.

Because Ekman Transport pushes water toward the center of the gyre from all sides the water piles up in a subtle dome. These domes can be up to 2 meters high and are measured by satellites.

Because the sine of zero is zero the Coriolis force is zero at the equator. Without this force to deflect water into a circle currents near the equator tend to flow in straight lines such as the Equatorial Counter Current.

The Beta Effect explains why western boundary currents are fast narrow and deep while eastern boundary currents are slow and shallow. This is a fundamental concept in physical oceanography.

When winds cause surface waters to move away from each other water must rise from below. This nutrient injection leads to blooms of phytoplankton even in the middle of the open ocean.

In the Southern Hemisphere net transport is 90 degrees to the left of the wind. If you face South which is the direction the wind is blowing your left is East.

While the perfect spiral is rare due to waves and turbulence sophisticated current meters have confirmed that the rotation of current direction with depth is a real and measurable phenomenon in the worlds oceans.

Divergence at the surface leads to upwelling while convergence leads to downwelling. This vertical movement is essential for cycling carbon and heat into the deep ocean.