Surface currents are extremely important because they distribute heat around the planet and are a major factor influencing climate around the globe. Winds on Earth are either global or local. Global winds blow in the same directions all the time and are related to the unequal heating of Earth by the Sun — that is, more solar radiation strikes the equator than the polar regions —- and the rotation of the Earth — that is, the Coriolis effect.
Wind is not the only factor that affects ocean currents. Coriolis causes freely moving objects to appear to move to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The objects themselves are actually moving straight, but the Earth is rotating beneath them, so they seem to bend or curve. An example might make the Coriolis effect easier to visualize. If an airplane flies miles due north, it will not arrive at the city that was due north of it when it began its journey.
Over the time it takes for the airplane to fly miles, that city moved, along with the Earth it sits on. The airplane will therefore arrive at a city to the west of the original city in the Northern Hemisphere , unless the pilot has compensated for the change. So to reach his intended destination, the pilot must also veer right while flying north. As wind or an ocean current moves, the Earth spins underneath it.
As a result, an object moving north or south along the Earth will appear to move in a curve, instead of in a straight line. Wind or water that travels toward the poles from the equator is deflected to the east, while wind or water that travels toward the equator from the poles gets bent to the west.
The Coriolis effect bends the direction of surface currents to the right in the Northern Hemisphere and left in the Southern Hemisphere. The Coriolis effect causes winds and currents to form circular patterns.
The direction that they spin depends on the hemisphere that they are in. Coriolis effect is demonstrated using a metal ball and a rotating plate in this video. When a surface current collides with land, the current must change direction.
At Brazil, some of it goes north and some goes south. Because of Coriolis effect, the water goes right in the Northern Hemisphere and left in the Southern Hemisphere. You can see on the map of the major surface ocean currents that the surface ocean currents create loops called gyres Figure below.
The Antarctic Circumpolar Current is unique because it travels uninhibited around the globe. Why is it the only current to go all the way around? The ocean gyres. Why do the Northern Hemisphere gyres rotate clockwise and the Southern Hemisphere gyres rotate counterclockwise? Even though the equator and poles have very different climates, these regions would have more extremely different climates if ocean currents did not transfer heat from the equatorial regions to the higher latitudes.
The Gulf Stream is a river of warm water in the Atlantic Ocean, about kilometers wide and about a kilometer deep. Water that enters the Gulf Stream is heated as it travels along the equator.
London, U. Because air traveling over the warm water in the Gulf Stream picks up a lot of water, London gets a lot of rain. Near the poles, Earth rotates at a sluggish 0. When you throw the ball to your friend, it will again to appear to land to the right of him.
Everywhere you play global-scale "catch" in the Northern Hemisphere , the ball will deflect to the right. This apparent deflection is the Coriolis effect. Fluids traveling across large areas, such as air currents, are like the path of the ball. They appear to bend to the right in the Northern Hemisphere.
The Coriolis effect behaves the opposite way in the Southern Hemisphere , where currents appear to bend to the left. The impact of the Coriolis effect is dependent on velocity —the velocity of Earth and the velocity of the object or fluid being deflected by the Coriolis effect. The impact of the Coriolis effect is most significant with high speeds or long distances.
The development of weather patterns, such as cyclones and trade winds, are examples of the impact of the Coriolis effect. As air masses are pulled into cyclones from all directions, they are deflected, and the storm system—a hurricane —seems to rotate counter-clockwise.
In the Southern Hemisphere, currents are deflected to the left. As a result, storm systems seem to rotate clockwise. Outside storm systems, the impact of the Coriolis effect helps define regular wind patterns around the globe. As warm air rises near the Equator, for instance, it flows toward the poles.
In the Northern Hemisphere, these warm air currents are deflected to the right east as they move northward. As the current descends, it gradually moves from the northeast to the southwest, back toward the Equator.
The consistently circulating patterns of these air masses are known as trade winds. The weather impacting fast-moving objects, such as airplanes and rockets, is influenced by the Coriolis effect. The directions of prevailing winds are largely determined by the Coriolis effect, and pilots must take that into account when charting flight paths over long distances.
Military snipers sometimes have to consider the Coriolis effect. The Earth rotates fairly slowly, compared to other known planets. The slow rotation of Earth means the Coriolis effect is not strong enough to be seen at slow speeds over short distances, such as the draining of water in a bathtub. Jupiter , on the other hand, has the fastest rotation in the solar system. On Jupiter, the Coriolis effect actually transforms north-south winds into east-west winds, some traveling more than kilometers miles per hour.
The boundaries between these fast-moving belts are incredibly active storm regions. The year-old Great Red Spot is perhaps the most famous of these storms.
Despite the popular urban legend , you cannot observe the Coriolis effect by watching a toilet flush or a swimming pool drain. You can observe the Coriolis effect without access to satellite imagery of hurricanes, however. You could observe the Coriolis effect if you and some friends sat on a rotating merry-go-round and threw or rolled a ball back and forth. When the merry-go-round is not rotating, rolling the ball back-and-forth is simple and straightforward.
Rolled with regular effort, the ball appears to curve, or deflect, to the right. Actually, the ball is traveling in a straight line. Another friend, standing on the ground near the merry-go-round, will be able to tell you this. You and your friends on the merry-go-round are moving out of the path of the ball while it is in the air. Coriolis Force The invisible force that appears to deflect the wind is the Coriolis force. The Coriolis force applies to movement on rotating objects.
It is determined by the mass of the object and the object's rate of rotation. The Coriolis force is perpendicular to the object's axis. The Earth spins on its axis from west to east. The Coriolis force, therefore, acts in a north-south direction. The Coriolis force is zero at the Equator. Though the Coriolis force is useful in mathematical equations, there is actually no physical force involved.
If a column of air cools, such as at the poles, it contracts and shrinks. That same stack of air — still weighing the same amount — will now be shorter and denser. This means that imaginary surfaces of constant density slope down toward the poles.
These lines rise up and down like bumps and wrinkles in a blanket, depending on local conditions. But the general downward slope allows masses of air to slide toward the poles. Thermal wind is what is created as those masses flow down this slope, carrying heat away from the equator. The equator would also be hot as a furnace.
As sun-warmed air rises near the equator and begins to move toward the poles, it also starts to drift eastward. It swirls the air from west to east around the planet. That poleward-moving air also speeds up — dramatically. If you took horizontal slices of the planet, those slices would be widest at the equator and narrowest at the poles.
This is because the air gets funneled into a smaller and smaller path. As it does so, its flow rate increases. In the Northern Hemisphere, this makes the air flow to the right with increasing speed.
This swirling action is known as the Coriolis force. This affects everything. A football tossed from one end of a stadium to another will naturally deflect 1. Closer to the mid-latitudes, they howl. This is how the jet stream forms. This current of air snakes around the planet at speeds greater than kilometers miles per hour. The more rapidly it moves, the more the northern jet stream curves east. But as the air moves poleward, it never actually gets to the poles. As a result, the jet stream meanders as it circles the Earth in each hemisphere.
In the North, it moves air west to east in a circle around the mid-latitudes and the opposite in the Southern Hemisphere , changing its path from season to season.
Poleward of the jet stream, the atmosphere is turbulent. Along this temperature boundary, a fierce atmospheric battleground develops. Colliding air masses of different temperatures spin up cyclones and other severe weather.
The position of the jet stream influences the type of weather a region encounters. Consider the Northern Hemisphere, for instance. This allows an extensive dome of super-cold air to bank up nearby. Atmospheric scientists refer to this flowing pool of cold air and low pressure as the polar vortex.
It swells in size during winter. And when this flow of cold air surges southward, it pushes the jet stream into southern Canada and the northern United States. That can bring seemingly endless snowstorms to the upper Midwest and Northeast during the dead of winter.
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