Ocean Currents

Ocean Currents Ocean currents are the routed movements of oceanic water which are constantly flowing within the ocean or on the ocean surface. An ocean current is created by several forces and elements that act upon a unit mass of water in the ocean and such factors on an environmental scale include the gravitational pull of the Moon and the Sun, wind, salinity levels, and the rotation of the earth, temperature and tidal waves. However, the two forces that create the most conducive conditions for a current to form are the Sun and the rotation of the Earth. Advertising We will write a custom essay sample on Ocean Currents specifically for you for only $16.05 $11/page Learn More Physical factors such as the depth of the ocean, contact with other currents and the composition of the shoreline will determine a currents course and potency. Ocean currents are known to surge for great distances and the gravitational centrifugal pull of great currents round the earth has a pivotal role in influencing the global climate especially of islands and coastal regions. It is well know that the California Current makes the weather of the Island of Hawaiian to be cooler as measure up to other regions which are situated at the same latitude, the current is a tropical one leading to the sub-tropical climate of the islands. Ocean currents also determine the marine life of a region because they play a major role in determining the salinity of the water. Currents can carry a large volume of highly saline water for great distances and the marine life of the region where the water gets deposited can significantly be altered. There are different currents are flowing at different levels in the ocean and it is possible for two or more currents to flow through a single region simultaneously but at different levels. There are generally two types of ocean currents depending on the water level where the movement of oceanic water takes place and they are the deep ocean currents and the surface ocean currents. Deep ocean currents are mainly caused by the fluctuation in the mass of water and by gravitational forces acting in the deeper parts of the ocean usually below three thousand feet. Variation in temperature and the salinity levels of the water cause a change in the mass and volume of water leading to deep ocean currents. A submarine river is another term which is used to refer to deep water currents basically because the currents occur in the lower levels of the ocean. The deep ocean currents carry large volumes of water which flow the greatest distances leading to thermohaline circulation. The submarine rivers are at times responsible for transferring deep water plankton and marine life from one part of the ocean to another and also cause the vertical movement of water in the upwelling and down welling parts in the oceans.Advertising Looking for essay on geology? Let's see if we can help you! Get your first paper with 15% OFF Learn More On the other hand, surface ocean currents take place on the upper levels of the ocean and are commonly caused by air currents acting on the ocean’s surface. Surface currents are composed of about ten percent of the total water volume in the ocean and are usually limited to the upper one thousand three hundred feet of the ocean. Surface currents form the Ekman spiral effect which is the circular movement of ocean surface water at a given tangent relative to the prevailing air currents. The Ekman spiral effect is usually in a clockwise direction in the northern hemisphere and in a counter-clockwise spiral in the southern hemisphere due the alternate air movements inflicted. However, the Indian Ocean does not follow this rule due to the strong torrential rains and the atmospheric system in northern region of the ocean which alters its trend twice every year. The southwest torrential rain which occurs off the coast of Somalia is caused by the Great Whirl, which is a stro ng current which has a circular motion. The currents on the ocean basin surface are normally asymmetric with the eastern currents flowing towards the equator and the western currents flowing towards the North and South poles. Such currents are majorly influenced by gravity, with the eastern currents flowing in separate extensive currents whereas the western currents for instance the Gulf Stream are relatively contracted. Deep water current movement patterns are formed through a complex process which begins with the freezing of the water in the ocean. Once the water is frozen, the salt in the ocean water is also condensed in the freezing process and this leads to the creation of a layer of cold salt concentrated water which forms near the surface of the water where freezing generally takes place. The brine then gradually sinks because of the density difference, brine being denser than the water below. The salt concentrated water is more viscous which makes it become denser than the water around it. Consequently, the gelatinous salty liquid sinks, leaving the surface levels of the ocean and will only settle when it gets to a region in the ocean where it bears an equal density to the surrounding ocean water. This process is very prominent in the Greenland and Labrador Seas that are located in the Northern Hemisphere, and the Weddell and Ross Seas in the Southern Hemisphere. Similar to surface currents, most of the current movement takes place on the western sides of ocean basins except that deep ocean currents have their progression towards the north. Advertising We will write a custom essay sample on Ocean Currents specifically for you for only $16.05 $11/page Learn More Surface currents flow in a succession of nearly circular gyres in the ocean basins. Most of the gyres are located in the western regions of the globe where the currents are contracted and carry large volumes of water for example the Gulf Stream, Agulhas and East Aust ralian Currents. The oceanic and atmospheric gyres help to move heat generated in the equatorial regions towards the poles. The polar movements of the ocean currents constitute the northward warm water current in the North Atlantic and in the North Pacific and the southward flow through the East Greenland and Labrador Currents. The surface currents that flow towards the equator move alongside the eastern edges of the gyres and are usually cooler than the currents that flow towards the poles located on the western margins. Air movement causes upwelling and provides the requisite wind stress towards the equatorial region moving water away from the coast and gravitational force pushes cooler subsurface water to replace the unoccupied water spaces. The Southern Ocean region experiences persistent westerly air movement leading to the Antarctic Circumpolar Current, a constant circumglobal current which hinders the formation of gyres. The Antarctic Circumpolar Current allows for the inte gration water from different ocean basins making it the largest current on earth. Sverdrup (Sv), is the standard unit used to measure ocean currents with one Sv being equivalent to a volume flow rate of one million cubic meters per second. The equatorial region experiences little or no gyres and currents here are usually surface currents stirred by the trade winds that originate from the eastern regions of the Northern Hemisphere and the Southern Hemisphere. The North and South Equatorial Currents which move toward the west are formed by trade winds which lead to an upwelling along the equator due to the movement of the southeast trade winds across the equator. Furthermore, the equatorial region does not incur Coriolis force which is potent even with a one degree shift north or south of the equator. The Doldrums region is formed in the equatorial region where the northern and southern currents border. The Doldrums region is generally permeable to the Equatorial Countercurrent wate r that flows back eastwards since the water would otherwise get concentrated on the western boundary allowing the doldrums region to act as an outlet. The velocity of the currents also varies, with the western currents moving faster than the eastern currents.Advertising Looking for essay on geology? Let's see if we can help you! Get your first paper with 15% OFF Learn More Marine life in the oceans is totally dependant on ocean currents for survival. Oxygen derived from the atmosphere is mixed with water through the flux of surface water like waves which are more or less generated by surface currents. For the oxygen to be delivered to the organisms, the oceanic currents and welling are needed to translocate the oxygen to all tiers of the ocean. Furthermore, marine victuals for instant phytoplankton which are minute organisms that are primary in the marine food chain are distributed in the ocean through the ocean currents. The organisms are usually caught in the currents and transported for great distances before being deposited in an ecosystem where they establish sustenance. Therefore ocean currents play an important role to both shallow and deep water organisms because they push food into the organisms’ environment. Surface organisms such as crabs are also reliant on the currents which carry microorganisms from the oceans and deposit them n ear the shores. In addition, currents provide inimitable signals in the life cycle of almost all marine organisms through transport of subtle chemical indicators. Turtles for instance migrate for long distances to mate and the precursor to their migration is the sensing of chemical triggers produced by sources that are more than a thousand miles away which are transported by ocean currents. Warm water used by marine life such as fish and turtles to incubate their eggs is deposited to the nesting grounds through ocean currents. Physical features such as lagoons are put together through the ocean currents which carry marine particles that are then deposited onto the lagoons leading to the expansion of the ecosystem. Due to the fact that ocean currents can move for great distances, they are also likely to spread out toxins in the oceans. For example, DDT which was a deadly insecticide was commonly used in America in the mid twentieth century. Through deltas, slight concentrations of the insecticide were moved to the ocean. The eventual consequence was that the product was found in penguins in both the north and south poles which had led to the thinning of the penguin egg shells. The only possible reason as to how the insecticide moved to such great distances is through ocean currents.

Bohr Model of the Atom - Overview and Examples

Bohr Model of the Atom s The Bohr Model has an atom consisting of a small, positively-charged nucleus orbited by negatively-charged electrons. Heres a closer look at the Bohr Model, which is sometimes called the Rutherford-Bohr Model. Overview of the Bohr Model Niels Bohr proposed the Bohr Model of the Atom in 1915. Because the Bohr Model is a modification of the earlier Rutherford Model, some people call Bohrs Model the Rutherford-Bohr Model. The modern model of the atom is based on quantum mechanics. The Bohr Model contains some errors, but it is important because it describes most of the accepted features of atomic theory without all of the high-level math of the modern version. Unlike earlier models, the Bohr Model explains the Rydberg formula for the spectral emission lines of atomic hydrogen. The Bohr Model is a planetary model in which the negatively-charged electrons orbit a small, positively-charged nucleus similar to the planets orbiting the Sun (except that the orbits are not planar). The gravitational force of the solar system is mathematically akin to the Coulomb (electrical) force between the positively-charged nucleus and the negatively-charged electrons. Main Points of the Bohr Model Electrons orbit the nucleus in orbits that have a set size and energy.The energy of the orbit is related to its size. The lowest energy is found in the smallest orbit.Radiation is absorbed or emitted when an electron moves from one orbit to another. Bohr Model of Hydrogen The simplest example of the Bohr Model is for the hydrogen atom (Z 1) or for a hydrogen-like ion (Z 1), in which a negatively-charged electron orbits a small positively-charged nucleus. Electromagnetic energy will be absorbed or emitted if an electron moves from one orbit to another. Only certain electron orbits are permitted. The radius of the possible orbits increases as n2, where n is the principal quantum number. The 3 → 2 transition produces the first line of the Balmer series. For hydrogen (Z 1) this produces a photon having wavelength 656 nm (red light). Bohr Model for Heavier Atoms Heavier atoms contain more protons in the nucleus than the hydrogen atom. More electrons were required to cancel out the positive charge of all of these protons. Bohr believed each electron orbit could only hold a set number of electrons. Once the level was full, additional electrons would be bumped up to the next level. Thus, the Bohr model for heavier atoms described electron shells. The model explained some of the atomic properties of heavier atoms, which had never been reproduced before. For example, the shell model explained why atoms got smaller moving across a period (row) of the periodic table, even though they had more protons and electrons. It also explained why the noble gases were inert and why atoms on the left side of the periodic table attract electrons, while those on the right side lose them. However, the model assumed electrons in the shells didnt interact with each other and couldnt explain why electrons seemed to stack in an irregular manner. Problems with the Bohr Model It violates the Heisenberg Uncertainty Principle because it considers electrons to have both a known radius and orbit.The Bohr Model provides an incorrect value for the ground state orbital angular momentum.It makes poor predictions regarding the spectra of larger atoms.It does not predict the relative intensities of spectral lines.The Bohr Model does not explain fine structure and hyperfine structure in spectral lines.It does not explain the Zeeman Effect. Refinements and Improvements to the Bohr Model The most prominent refinement to the Bohr model was the Sommerfeld model, which is sometimes called the Bohr-Sommerfeld model. In this model, electrons travel in elliptical orbits around the nucleus rather than in circular orbits. The Sommerfeld model was better at explaining atomic spectral effects, such the Stark effect in spectral line splitting. However, the model couldnt accommodate the magnetic quantum number. Ultimately, the Bohr model and models based upon it were replaced Wolfgang Paulis model based on quantum mechanics in 1925. That model was improved to produce the modern model, introduced by Erwin Schrodinger in 1926. Today, the behavior of the hydrogen atom is explained using wave mechanics to describe atomic orbitals. Sources Lakhtakia, Akhlesh; Salpeter, Edwin E. (1996). Models and Modelers of Hydrogen. American Journal of Physics. 65 (9): 933. Bibcode:1997AmJPh..65..933L. doi:10.1119/1.18691Linus Carl Pauling (1970). Chapter 5-1.  General Chemistry  (3rd ed.). San Francisco: W.H. Freeman Co. ISBN 0-486-65622-5.Niels Bohr (1913). On the Constitution of Atoms and Molecules, Part I (PDF). Philosophical Magazine. 26 (151): 1–24. doi:10.1080/14786441308634955Niels Bohr (1914). The spectra of helium and hydrogen. Nature. 92 (2295): 231–232. doi:10.1038/092231d0