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| Name: 10calama | Date: Nov 26th, 2007 2:51 AM |
| The Coriolis effect is the apparent deflection of moving objects from a straight path when they are viewed from a rotating frame of reference. A pycnocline is a layer across which there is a rapid change in water density with depth. In freshwater environments such as lakes this density change is primarily caused by water temperature, while in seawater environments such as oceans the density change may be caused by changes in water temperature and/or salinity. A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents are locally very common on Earth because it is both geologically active and has large amounts of water on its surface and within its crust. Common land types include hot springs, fumaroles and geysers. The most famous hydrothermal vent system on land is probably within Yellowstone National Park in the United States. Under the sea, hydrothermal vents may form features called black smokers. Bathymetry is the underwater equivalent to topography. The name comes from Greek βαθυς, deep, and μετρον, measure. In other words, bathymetry is the study of underwater depth, of the third dimension of lake or ocean floors. A bathymetric map or chart usually shows floor relief or terrain as contour lines, and may additionally provide surface navigational information. The data used to make bathymetric maps today typically comes from an echosounder (sonar) mounted beneath or over the side of a boat, "pinging" a beam of sound downward at the seafloor or from remote sensing LIDAR or LADAR systems. The amount of time it takes for the sound or light to travel through the water, bounce off the seafloor, and return to the sounder tells the equipment how far down the seafloor is. LIDAR/LADAR surveys are usually conducted by airborne systems. Pelagic sediments, also known as marine sediments, are those that accumulate in the abyssal plain of the deep ocean, far away from terrestrial sources that provide terrigenous sediments; the latter are primarily limited to the continental shelf, and deposited by rivers. Pelagic sediments that are mixed with terrigenous sediments are known as hemipelagic. There are three main types of pelagic sediments: 1.) Siliceous oozes 2.) Calcareous oozes 3.) Red clays Calcareous ooze is composed primarily of the shells--also known as tests--of foraminifera, coccolithophores, and pteropods. This is the most common pelagic sediment by area, covering 48% of the world ocean's floor. It accumulates more rapidly than any other pelagic sediment type, with a rate that varies from 0.3 - 5 cm / 1000 yr. Siliceous ooze is composed of the debris of plankton with silica shells, such as diatoms and radiolaria. This ooze is limited to areas with high biological productivity, such as the polar oceans, and upwelling zones near the equator. The least common type of sediment, it covers only 15% of the ocean floor. It accumulates at a slower rate than calcareous ooze: 0.2-1 cm / 1000 yr. Red clay, also known as pelagic clay, accumulates in the deepest and most remote areas of the ocean. Containing less than 30% biogenic material, its composition is a varied mix of very fine quartz and clay minerals, authigenic deposits precipitated directly from seawater, and micrometeorites. Though called "red" because it sometimes takes the color of oxidized iron minerals, it is usually brownish in color. Its ultimate origin is uncertain, but red clay seems to be mostly derived from distant rivers, and windblown dust. Covering 38% of the ocean floor, it accumulates more slowly than any other sediment type, at only 0.1-0.5 cm / 1000 yr. Properties of seawater: Temperature, pressure, and salinity are the three most important properties of seawater, and they determine the other physical properties associated with seawater. This differs from pure water, where only pressure and temperature determine the physical properties. Wave motion and the presence of small suspended particles in seawater are also important variables that affect the properties of seawater. Wave motion causes a change in the processes of chemical diffusion, heat conduction, and transfer of momentum from one layer to another. The suspended particles increase the scattering of radiation, thereby absorbing more radiation than a similar layer (thickness) of pure water. The variables of wave motion and suspended particles, although important, cannot be measured. In addition to temperature, pressure, and salinity, other common physical properties of seawater are water color, transparency, ice (which we’ve already covered in our discussion of the surface), and sound velocity. Some of the lesser known properties include specific heat, compressibility, osmotic pressure, eddy viscosity, electrical conductivity, radioactivity, and surface tension. Many of the lesser known properties can only be determined using complex mathematical calculation and formulation that incorporates data on one or more of the common physical properties, especially temperature, pressure, and/or salinity. El Niño refers to the irregular warming in the sea surface temperatures from the coasts of Peru and Ecuador to the equatorial central Pacific. This causes a disruption of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe. This phenomenon is not totally predictable but on average occurs once every four years. It usually lasts for about 18 months after it begins. La Niña is a coupled ocean-atmosphere phenomenon similar to El Niño. During a period of La Niña, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 0.5 °C. By definition, an episode of La Niña is a period of at least 5 months of La Niña conditions. The name La Niña originates from Spanish, meaning "the little girl", analogous to El Niño meaning "the little boy". La Niña is the opposite of El Niño, where the latter corresponds instead to a higher sea surface temperature by a deviation of at least 0.5 °C. El Niño is famous due to its potentially catastrophic impact on the weather along both the Chilean and Australian coasts. Furthermore, La Niña is often preceded by a strong El Niño. Ocean Salinity Over millions of years, rain, rivers, and streams have washed over rocks containing the compound sodium chloride (NaCl), and carried it into the sea. You may know sodium chloride by its common name: table salt! Some of the salt in the oceans comes from undersea volcanoes and hydrothermal vents. When water evaporates from the surface of the ocean, the salt is left behind. After millions of years, the oceans have developed a noticeably salty taste. Different bodies of water have different amounts of salt mixed in, or different salinities. Salinity is expressed by the amount of salt found in 1,000 grams of water. Therefore, if we have 1 gram of salt and 1,000 grams of water, the salinity is 1 part per thousand, or 1 ppt. The average ocean salinity is 35 ppt. This number varies between about 32 and 37 ppt. Rainfall, evaporation, river runoff, and ice formation cause the variations. For example, the Black Sea is so diluted by river runoff, its average salinity is only 16 ppt. Freshwater salinity is usually less than 0.5 ppt. Water between 0.5 ppt and 17 ppt is called brackish. Estuaries (where fresh river water meets salty ocean water) are examples of brackish waters. Ekman transport, named for Vagn Walfrid Ekman, is the natural process by which wind causes movement of water near the ocean surface. Each layer of water in the ocean drags with it the layer beneath. Thus the movement of each layer of water is affected by the movement of the layer above, or below in the case of a frictional bottom boundary layer. It is obtained by vertically integrating the Ekman spiral. Because of the Coriolis effect, the ocean's surface movement is 45° to the right of direction of surface wind in the Northern Hemisphere, and 45° to the left in the Southern Hemisphere. The average movement of ocean water at all depths (and thus the Ekman transport) is 90° to the right of the wind in the Northern Hemisphere, and 90° to the left in the Southern Hemisphere. If such a current transports water away from a coast, it creates an upwelling of deep, nutrient-rich sea water. This has the effect of creating good fishing regions along coasts where this phenomenon occurs. An amphidromic point is a point within a tidal system where the tidal range is almost zero Amphidromic points occur because of the coriolis effect and interference within oceanic basins and bays creating a wave pattern which rotates around the amphidromic point. At the amphidromic point, there is almost no vertical movement. There can be tidal currents as the water levels on either side of the amphidromic point are not the same. Amphidromic points occur at Tahiti, off the coast of Newfoundland, near the South Shetlands, midway between Rio de Janeiro and Angola, at three points in the North Sea and in general at several more points in the Pacific Ocean, Atlantic Ocean and Indian Ocean. The island of Madagascar is an amphidromic point, as is New Zealand. Length. The dimensions of the vessel can be used to wave period can be determined by measuring the interval between passages of wave crests past the observer. The relative motion of the vessel can be eliminated by timing the passage of successive wave crests past a patch of foam or a floating object at some distance from the vessel. Accuracy of results can be improved by averaging several observations. Period. If allowance is made for the motion of the vessel determine wavelength. Errors are introduced by perspective and disturbance of the wave pattern by the vessel. These errors are minimized if observations are made from maximum height. Best results are obtained if the sea is from dead ahead or dead astern. Speed. Speed can be determined by timing the passage of the wave between measured points along the side of the ship, if corrections are applied for the direction of travel for the wave and the speed of the ship. The length, period, and speed of waves are interrelated by the relationships indicated previously. There is no definite mathematical relationship between wave height and length, period, or speed.   ↑ |
| Name: 10calama | Date: Dec 7th, 2007 12:58 PM |
| Procedures list 1. Two tests of equal difficulty were created. They test basic math skills at different levels of difficulty, and memory of a seven-digit number over a span of one minute. 2. One test was given to Mrs. Thomas’s 2nd hour class before the lesson the other was given to the class after the days lesson. There will be approximately 18 students participating. This was the control. 3. The two tests were corrected taking note of any constant inconsistencies between the tests (making appropriate adjustments in both the test and the scores) and also taking note of individual changes in test score between the first and second test. 4. The results of the control were graphed into a pie chart showing percentages of those who increased test results, those who had a decrease in their scores, and those who had no change between the two scores. 5. The first test was given to BSA troop 473 at one of their weekly meetings, there were be approximately 13 people participating. 6. The scouts spent 30 minutes playing non-educational video games in groups of four. 7. After playing, the scouts took part two of the test. 8. The scores of the scouts were tallied, paying attention only to changes in score between the two tests. (Education level will not be a factor in these tests because if a person does not know how to do a question, they will not know how to do it’s counterpart on the second so the two will cancel out.) 9. A second pie chart was made for these scores showing the same percentage groups as before. 10. Another BSA troop and/or students enrolled in Gladstone schools will take the first test, there were be approximately 13 people participating here also, play educational video games for 30 minutes, and take the second test, there were be approximately 13 people participating here also. 11. These results will be recorded and a third pie chart will be made showing the same percentage groups as the ones before. 12. The three charts were compared and contrasted to come up with a conclusion. Christopher LaMarche P.S. just another file ↑ |
| Name: lila | Date: Jul 20th, 2011 9:32 AM |
| nahid ↑ |
