Oceans And Waves Part 2

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gyers

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gyros=circle. Huge circular-moving current systems dominating the surface of the ocean. North pacific, south pacific, north atlantic, and south atlantic and indian ocean gyres. which exist mostly within the southern hemisphere.

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subtropical gyres

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The center of each gyre consides with the subtropics at about 30 degrees north or south laittude,

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Coriolis effet

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because of earth's rotation, currents are deflected to the right in the Northern Hemisphere and to the left in the southern hemisphere.

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The north pacific gyre

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consists of the north equatorial current, the kuroshio current, the north pacific current, and the californica current.

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North atlantic ocean

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The north equatrial curernt is deflected northward. As the Gulf stream moves along the east coast of the US, it is strengthen by the prevailing westerly winds and deflected to the east towards the North atlantic current, then the atlantic drift.

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Saragassum

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a type of floating seaweed encountered there.

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Southern Heimisphere currents

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with surface currents influenced by wind belts, the position of continents, and the Coriolis effect. The West Wind Drift is the only current that completely encircles earth. It flows around the ice-covered continents of antartica.

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Indian Ocean Currents

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exists mostly in the southern hemisphere, and it follws a surface circulation pattern similar to those in other Southern Hemisphere ocean basins.

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Monosoons

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Mausim = seasons During the summer, winds blow fro mthe INdian Ocean toward the Asian landmass. In the winter, the winds revers an d blow out from asia over the Indian Ocean.

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the transcer of heat by winds and ocean currents

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equalizes these latitudinal energy imbalances.

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warm currents

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The North Atlantic Drift an extension of the warm Gulf stream, keeps wintertime temperatures in Great britian and much of Western Europe warmer than would be expected for their latitudes. London is farther north than st. john's, newfoundland, et is not nearly so frigid in winter.

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cold currents

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exert their greatest influence in the tropics or during the summer months in the middle latituded, benguela current off the western coast of southern africa moderates the tropical heat along this coast.

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Aridity

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along the west coast of continents. is intensified because the lower atmosphere is chilled by cold offshore waters. When this occures, the aire becomes very stable and resists the upward movement necessary to creat precipitation-producing clouds.

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upwelling

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the rising of cold water from deeper lays to replace warmer surface water is a common wind-induced vertical movment. Brings greater concentraions of dissolved nutrients such as nitrates and phosphates. Promotes the growth of microscopic plankton, which in turn support extensive populations of fish and other marine organisms

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costal upwelling

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most characteristic along the west coasts of continents, most notably along california, western south america, and west africa. When winds blow towards the equator and parallel to the coast.

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Deep-ocean circulation/ Thermohaline (thermo = heat, haline = salt)

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a significant vertical component and accounts for the thorough mixing of deep water masses. A response to density differences among water masses that cause denser water to sink and slowly spread out beneath the surface.

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sewater density increase

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can be caused by eaither a decrease in temperature or an increase in salinity. Density changes due to salinity variations are important in very high latitudes, where water temperature remains low and relatively constant.

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interface

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a common boundary where different parts of a system interact.

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the coastal zone

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we can see the rhythmic rise and fall of tides and obeserve waves rolling in and breaking. sometimes the waves are low and gentle. at other times, they pound the shore with awesome fury. october 2012 hurricaine

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ocean waves

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energy traveling along the interface between ocean and atmosphere, often transferring energy from a storm far out at sea over distances of several thousand kilometers.

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wind generated waves

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provide most of the energy that shapes and modifies shorelines. Where the land and sea meet, waves that may have traveled unimpeded for hundreds or thousands of kilometers suddenly encounter a barrier that will not allow them to advance farther and must absorb their energy.

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Crests

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the tops of the waves which are separated by troughs

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still water level

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halfway between the crests and troughs. the level that the water would occupy if there were no waves.

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wave height

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the vertical distance between through and crest

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wavelength

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the horizontal distance between successive crests (or troughs).

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wave period

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The time it takes one full wave - one wavelength - to pass a fixed postion

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wave dependent factors

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1. wind speed

2. length of time the wind has blown

3. fetch, the distance that wind has traveled across open water. As the quantity of energy transferred from the wind to the water increases, both the height and steepness of the waves increase.

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white caps

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a critical point is reached where waves grow so tall that they topple over forming ocean breakers

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maximum fetch and duration

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for a given wind velocity, the waves are said to be "fullly developed: The reason that waves can grow no further is that they are losing as much energy throug hthe breaking whitecaps as they are receiving from the wind

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swells

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lower in height and longer in length and may carry a storm's energy to distant shores. Because many independent wave systems exist at the same time, the sea surface acquires a complex and irregular pattern, sometimes producing very large waves.

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circular orbital motion

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Aleutian islands of Alaska. As the wave travels, the water passes the energy along by moving in a circle. allows a waveform (the wave's shape) to move forward through the water, while the individual water particles that transmit the wave move around in a circle.

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wave base

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the circular motion rapidly dimishes until, at a depth equal to one-half the wavelength measured from the still water level, the movement of the water particles become negligible.

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surf

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the turbulent water created by breaking waves.

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swash

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the turbulent sheet of water from collapsing breakers.

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backwash

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when the energy of the swash has been expended, the water flows back down the beach toward the surf zone

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beach

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an accumulation of sediment found along the landward margins of an ocean or a lake. may extend for tens or hundreds of kilometers. Where coasts are irregular. "rivers of sand"

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abrasion

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the sawing and grding action of the water armed with rock fragements. More intense in the surf zone than in any other environment. Smooth, rounded stones and pebbles along the shore are obvious reminders of the relentless gridng action of rock against rock in the surf zone.

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When wave activity is relatively light (less energetic waves)

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much of the swash soaks into the beach, which reduces the back wash. rule the summer

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High energy waves prevail

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the beach is saturated from previous waves, so much less of the swash soak in. As a result, the beach erodes because backwash is strong and causes a net movement of sand toward open water.

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wave refraction

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the bending of waves plays an important part in shoreline processes. it affects the distribution of energy along the shore an thus strongly influences where and to what degree erosion, sediment transport, and depostion will take place.

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beach drift

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the effect of this pattern of water movement is to transport sediment in a zigzag pattern along the beach face and it can transport sand and pebbles hundreds or even thousands of meters daily.

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long shore currents

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Waves that apporach the shore at an angle also produce currents within the surf zone that flow parallel to the shore and move substantially more sediment than beach drift. easily move the fine suspended sand and roll larger sand and gravel along the bottom.

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eronsional features

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Wave-cut cliffs, wave-cut plateforms, and marine terraces

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Wave-cut cliffs

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originate in the cutting action of the surf against the base of coastal land. As erosion progresses, rocks overhanging the notch at the base of the cliff crumble into the surf and the cliff retreats

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wave-cut plateform

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a relatively flat, benchlike surface, is left behind by the receding cliff.

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marine terraces

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if a wave-cut platform is uplifted above sea level by tectonic forces. easily recognized by their gentle seaward-sloping shape and are often perceived as desirable sites for coastal development

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sea arch

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when two caves on opposite sides of a headland unite.

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sea stack

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the arch falls in, leaving an isolated remnant

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depositional features

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spits, bars, and tombolos, varrier island

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spit

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an elongated ridge of sand that projects from the land into the mouth of an adjacent bay. Often the end in the water hooks landward in response to the dominant direction of the longshore current

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baymouth bar

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applied to a sandbar that completely crosses a bay, sealing it off from the open ocean.

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tombolo

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a ridge of sand that connects an island to mainland or to another island, forms in much the same manner as a spit

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Barrier islands

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The atlantic and gulf coastal plains are relatively flat and slope gently seaward

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hard statabilization

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structures build to protect a coast from erosion or to prevent the movement of sand along a beach. can take many forms and often results in predictable yet unwanted outcomes.

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Groins

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to maintain or widen beaches that are losing sand, a barrier build at a right angle to the beach to trap sand that is moving parallel to the shore.

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groin field

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To offset this effect, property owners downstream from the structure may erect a groin on their property

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breakwater

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designed to protect boats from the force of large breaking waves by creating a quiet water zone near the shore.

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seawall

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designed to armor the coast and defend property from the force of breaking waves. reflecting the force of unspent waves seaward.

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beach nourishment

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One approach to stabilizing shoreline sands without hard stabilization. adding large quantities of sand to the beach system.

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relocating

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river floodplains following the devastating 1993 missippi river floods

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emergent coasts

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develop either because an area experiences uplift or as a result of a drop in sea level. rising land or falling water levels expose wave cut cliffs and marine terraces above sea level. include regions that were once buried beneath great ice sheets.

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submergent coasts

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created when sea level rises or the land adjacent to the sea subsides. the sea typically floods the lower reaches of river valleys flowing into the ocean. The ridges separating the vellys, however, remain above sea level and project into the sea as headlands

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estuaries

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characterize many coast today. Chesapeake and Delaware bays are examples of estuaries created by submergence

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tides

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Are daily changes in the elevation of the ocean surface. Their rhythmic rise and fall along coastlines have been known since antiquity. Other than waves, they are the easiest ocean movements to observe. Sir Issac Newton law of gravity.

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tidal bulges

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pull of gravity. the inversely proportonal to the square of distance between two objects, meaning simply that i quickly weakens with distance.

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spring tides

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the combined gravity of two tide-producing bodies causes larger tidal buldges (higher high tides) and larger tidal troughs (lower low tides), pproducing a large tidal range. have no connection with the springs season but occur twice a month when the earth moon and sun system align

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neap tides

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occur twich each moth. Each moth, then, there are two spring tides and two neap tides, each about 1 week apart

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Diurnal tidal pattern

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diurnal = daily. a single high tide and a single low tide each tidal day. occur along the northern shore of the golf of mexico

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semidiuranal tidal pattern

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semi - twice, two high tides and two low tides each day, with the same height.

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mixed tidal pattern

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similar to a semidiurnal pattern except that it is characterized by a large inequality in high-water heights, low water heights, or both.

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tidal currents

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describe the horizonal flow of water accompanying the rise and fall of the tides.

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flood currents

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tidal currents that advance into the coastal zone as the tide rises.

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ebb currents

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as the tidee falls, seaward-moving water

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slack water

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periods of little or no current separate flood and ebb

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tidal flats

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the areas affected by these alternating tidal currents.

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tidal deltas

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develop either as flood deltas landward of inlet or as a ebb deltas on the seawrd side of an inlet. because wave activity and longeshore currentsare reduced on the sheltered landward side, flood deltas are more common and actually more prominent