Introduction to Ocean Currents
WHAT IS IT/ HOW ARE THE CAUSED?
An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow. Such as breaking waves, wind, Coriolis effect, cabbeling, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun.
An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow. Such as breaking waves, wind, Coriolis effect, cabbeling, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun.
What is the Gulf Stream Current?
The Gulf Stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates at the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean. The process of western intensification causes the Gulf Stream to be a northward accelerating current off the east coast of North America.
What are surface circulation and deep circulation?
Surface Circulation: Surface ocean currents are generally wind-driven and develop their typical clockwise spirals in the northern hemisphere and counter-clockwise rotation in the southern hemisphere because of the imposed wind stresses. In wind-driven currents, the Ekman spiral effect results in the currents flowing at an angle to the driving winds. The areas of surface ocean currents move somewhat with the seasons; this is most notable in equatorial currents.
Deep Circulation: Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation, also known as the ocean's conveyor belt, refers to the deep ocean density-driven ocean basin currents. These currents, which flow under the surface of the ocean and are thus hidden from immediate detection, are called submarine rivers.
Deep Circulation: Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation, also known as the ocean's conveyor belt, refers to the deep ocean density-driven ocean basin currents. These currents, which flow under the surface of the ocean and are thus hidden from immediate detection, are called submarine rivers.
What is a gyre? Where are they located?
A gyre in oceanography is any large system of rotating ocean currents, particularly those involved with large wind movements. Gyres are caused by the Coriolis Effect; planetary vorticity along with horizontal and vertical friction, which determine the circulation patterns from the wind curl (torque). The term gyre can be used to refer to any type of vortex in the air or the sea, even one that is man-made, but it is most commonly used in oceanography to refer to the major ocean systems.
What are the most important factors of surface currents?
Wind and Gravity are the most important factors of surface currents. When strong sustained winds blow across the sea, friction drags a thin layer of water into motion. Currents run under the gentle slopes due to the pull of gravity.
What happens to the tropics during summer to water level?
During the summer, the tropics become very heated which causes the water to expand which leads to the rise of water levels by several meters.
Thermohaline Circularion
Density variations in the ocean. Thermohaline circulation depends on temperature and salinity. It begins in the surface of the seawater which is near the poles. The water then gets colder due to the low temperatures. Polar seawater gets saltier, and the colder and saltier the water gets the more dense it becomes causing it to sink.
The effect of the Coriolis Effect on airplane flights
The Coriolis Effect can change airplane flights because when objects move towards higher, slower moving latitudes, it out paces the rotation of the surface and veers to the east. When they move to lower, faster moving latitudes, they lag behind.
Temporary currents
Temporary currents are currents that only run on certain seasons or weather conditions. Longshore currents flow along coastlines when waves run into the shore at an angle. They bulldoze great volumes of sand along the shore causing the beaches to disappear and harbors to fill in. Rip currents form where obstacles channel water away from the shore line. These are dangerous because people in the water can be swept out into sea. Upwelling currents are currents where wind pushes surface water away from the shore and deeper water pushes in to fill in the gaps.
What can trigger the phenomena called the El Nino?
Very warm equatorial current that flows eastward can trigger the phenomena called El Nino.
Global Conveyor Belt
The global conveyor belt slowly but steadily empties one ocean into another ocean and over a course of 1000 years, turns the water upside down. The global conveyor belt has a volume 16 times the combined flows of all the world's rivers.
Coriolis Effect
The Coriolis Effect occurs because the earth rotates quicker at the equator than at the poles. It influences the paths of moving objects loosely in contact with the ground.
Global Impacts of Currents
The importance of currents to humans
Currents are important to humans because they partially regulate the global climate and governs the productivity of fisheries.
Benefit of Upwelling to people
Upwelling is "the rise of deeper water to the surface. It makes up half of the world's fisheries.
How currents affect Earth's temperature
Ocean currents moderate the planet's temperature extremes.
How global warming affects ocean currents
Warm, fresh water from rainfall floats on top of the cold, salty water. Blocking the sinking of cold, salty water. This can turn off the global conveyer belt.
Ocean Waves
Explain the movement of water molecules within a wave.
Within a wave, individual water molecules move in circles that get smaller with depth and eventually stop altogether. Boats or bottles or other debris floating on the surface don’t go anywhere either, but simply bob up and down.
Within a wave, individual water molecules move in circles that get smaller with depth and eventually stop altogether. Boats or bottles or other debris floating on the surface don’t go anywhere either, but simply bob up and down.
What do waves transmit across the sea?
The only thing waves do transmit across the sea is energy.
Explain wave anatomy
Wave anatomy is very simple. The highest surface part of a wave is called the crest, and the lowest part is the trough. The vertical distance between the crest and the trough is the wave height. The horizontal distance between two adjacent crests or troughs is known as the wavelength.
What are most waves generated by?
Many things, from moving ships to earthquakes, to a bird skipping across the water, cause waves, but most are generated by wind. When wind blows across the sea surface, the friction between the air and water kicks up a series of small ripples.
When do waves reach their maximum size?
The waves grow higher, longer, and faster, reaching their maximum size when they nearly match the speed of the wind.
Where are the largest waves on earth found? Why?
The largest waves on Earth, shown in orange and red, form where strong winds blow steadily across miles of open sea. The longer and further the wind blows, the bigger and faster the waves become.
What is a wave train? What happens when there is interference of waves trains?
In deep water, a group of wind-driven waves, called a wave train, develops into a series of harmonious, rounded swells. The train keeps moving even as it leaves behind the wind that formed it. In the open sea, wave trains soon encounter other sets of waves traveling in different directions and with different speeds, heights, and wavelengths. Interference between wave trains can produce a confused, highly irregular sea.
What is a rogue wave? How are they created? How big can they get?
Sometimes, wave energy can be focused by the interaction of wave trains with currents or perhaps other waves to produce a freakishly large, or rogue, wave. The phenomenon of rogue waves is poorly understood, but it appears these waves can reach a height of 100 feet and are responsible for many shipwrecks.
What happens to waves in shallow water?
When waves move into shallow water, their behavior changes dramatically. The definition of shallow water depends on the size of the wave—at a depth of half the wavelength, the wave starts to “feel the bottom”—the deepest circling water molecules come in contact with the seafloor. Friction between the seafloor and the water profoundly changes the speed, direction, and shape of waves.
What is swash? What does it do? How it is involved in erosion?
The deepest part of the wave slows down more than the top of the wave. The wave begins to lean forward as the crest rushes ahead of the base. Eventually the wave topples over and breaks against the shore. The wave collapses into foaming sheets of water, called swash, that roll up and then down the beach, carrying along sand and gravel. Waves caused by the wind can erode the coast, bulldoze nearshore sediments, and generate strong currents. These effects are the cumulative result of wave after wave, day after day, endlessly pounding against the shore.
What is a tsunami?
Another type of wave is much more powerful, able to remodel the coast, not over the space of years, but in just a few hours. These waves are the largest and most energetic on Earth and are called tsunami. In deep water, wind waves travel between 5 and 65 miles per hour, may reach heights of 45 feet, and are no more than a few hundred feet apart. Tsunami are barely noticeable in the open sea – their height is just three feet or less, and successive wave crests are miles apart. These waves travel very fast, racing across an ocean at the speed of a jet.
What are some of the causes of tsunamis?
Tsunami are caused by geologic events that push away a mass of water. Underwater landslides, volcanic eruptions, even asteroids falling into the sea from space, can spawn tsunami. But most are caused by earthquakes When a quake suddenly shoves a large piece of seafloor up or down, the entire overlying ocean moves too. The displaced water rushes away from the disturbance in waves that spread in all directions.
Global Impact
How can we generate electricity from wave power? Some attempts have been made to harness the relentless power of waves and turn it into electricity. Generator designs vary, but all rely on the up and down motion of waves to spin turbines and produce electricity.
How much possible electricity could wave power generated?
The idea of wave power is appealing—waves are free and non-polluting. Although the technology is still under development, it holds great promise and scientists estimate wave power could supply two times the electricity the world currently consumes.
How many people have been killed by tsunamis?
Over all of recorded history, perhaps 1 million people have died in tsunami. The most deadly struck in 2004, killing more than 250,000 people from Indonesia to Africa.
What can be done about tsunamis to help protect people and property?
Spurred by this and earlier disasters, many governments are working to install warning systems and rebuild natural coastal barriers to tsunami. Unfortunately, the incredible power of these waves guarantees that tsunami will continue to extract a high toll from those who live and play along the shore.