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98-562: Total area of this thana is 9.64 km (3.72 sq mi) Anandabazar is a coastal area located at Halishahar, near Bay of Bengal . As of 2014, the Chittagong Port Authority (CPA) was also starting a process for developing a Bay Terminal on about 1000 acres of land along the coastal area at Anandabazar, near the Port of Chittagong . Anandabazar post office and Ananda Bazar Government Primary School are also located in this place. There

196-527: A navy and some form of coast guard . Coasts, especially those with beaches and warm water, attract tourists often leading to the development of seaside resort communities. In many island nations such as those of the Mediterranean , South Pacific Ocean and Caribbean , tourism is central to the economy . Coasts offer recreational activities such as swimming, fishing, surfing, boating, and sunbathing . Growth management and coastal management can be

294-478: A challenge for coastal local authorities who often struggle to provide the infrastructure required by new residents, and poor management practices of construction often leave these communities and infrastructure vulnerable to processes like coastal erosion and sea level rise . In many of these communities, management practices such as beach nourishment or when the coastal infrastructure is no longer financially sustainable, managed retreat to remove communities from

392-738: A high pressure (anticyclonic) systems such as the Azores-Bermuda high develops a gyre circulation with slow steady flows towards the equator in the interior. As discussed by Henry Stommel , these flows are balanced in the region of the western boundary, where a thin fast polewards flow called a western boundary current develops. Flow in the real ocean is more complex, but the Gulf Stream , Agulhas and Kuroshio are examples of such currents. They are narrow (approximately 100 km across) and fast (approximately 1.5 m/s). Equatorwards western boundary currents occur in tropical and polar locations, e.g.

490-655: A much higher capacity for carbon sequestration than many terrestrial ecosystems , and as such can play a critical role in the near-future to help mitigate climate change effects by uptake of atmospheric anthropogenic carbon dioxide . However, the economic importance of coasts makes many of these communities vulnerable to climate change , which causes increases in extreme weather and sea level rise, as well as related issues like coastal erosion , saltwater intrusion , and coastal flooding . Other coastal issues, such as marine pollution , marine debris , coastal development, and marine ecosystem destruction, further complicate

588-625: A proper name to the coast of the Ligurian Sea , in the form riviera ligure , then shortened to riviera . Historically, the Ligurian Riviera extended from Capo Corvo (Punta Bianca) south of Genoa , north and west into what is now French territory past Monaco and sometimes as far as Marseilles . Today, this coast is divided into the Italian Riviera and the French Riviera , although

686-435: A provider of sediment for coastlines of tropical islands. Like the ocean which shapes them, coasts are a dynamic environment with constant change. The Earth 's natural processes, particularly sea level rises , waves and various weather phenomena, have resulted in the erosion , accretion and reshaping of coasts as well as flooding and creation of continental shelves and drowned river valleys ( rias ). More and more of

784-436: A result of heat storage in summer and release in winter; or of transport of heat from warmer locations: a particularly notable example of this is Western Europe , which is heated at least in part by the north atlantic drift . Surface winds tend to be of order meters per second; ocean currents of order centimeters per second. Hence from the point of view of the atmosphere, the ocean can be considered effectively stationary; from

882-508: A result, tiny variations in pressure can produce measurable currents. A slope of one part in one million in sea surface height, for example, will result in a current of 10 cm/s at mid-latitudes. The fact that the Coriolis effect is largest at the poles and weak at the equator results in sharp, relatively steady western boundary currents which are absent on eastern boundaries. Also see secondary circulation effects. Ekman transport results in

980-456: A shoreline configuration. Swash is the shoreward flow after the break, backwash is the water flow back down the beach. The relative strength of flow in the swash and backwash determines what size grains are deposited or eroded. This is dependent on how the wave breaks and the slope of the shore. Depending on the form of the breaking wave, its energy can carry granular material up the beach and deposit it, or erode it by carrying more material down

1078-425: A slightly different way in discussions of legal and economic boundaries (see territorial waters and international waters ) or when considering the geography of coastal landforms or the ecological systems operating through the continental shelf ( marine coastal ecosystems ). The research on coastal waters often divides into these separate areas too. The dynamic fluid nature of the ocean means that all components of

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1176-476: A subtropical ocean basin (the Sverdrup balance ). The return flow occurs in an intense, narrow, poleward western boundary current . Like the atmosphere, the ocean is far wider than it is deep, and hence horizontal motion is in general much faster than vertical motion. In the southern hemisphere there is a continuous belt of ocean, and hence the mid-latitude westerlies force the strong Antarctic Circumpolar Current . In

1274-573: A sudden shift in the wind, such as the change of the trade winds at the beginning of the El Niño-Southern Oscillation . Coastal Kelvin waves follow shorelines and will always propagate in a counterclockwise direction in the Northern hemisphere (with the shoreline to the right of the direction of travel) and clockwise in the Southern hemisphere . Equatorial Kelvin waves propagate to

1372-488: A time scale of decades. Known climate oscillations resulting from these interactions, include the Pacific decadal oscillation , North Atlantic oscillation , and Arctic oscillation . The oceanic process of thermohaline circulation is a significant component of heat redistribution across the globe, and changes in this circulation can have major impacts upon the climate. This is a coupled ocean / atmosphere wave that circles

1470-578: A vertical temperature gradient that divides the ocean into distinct layers. Salinity, a measure of the concentration of dissolved salts in seawater, typically ranges between 34 and 35 parts per thousand (ppt) in most of the world’s oceans. However, localized factors such as evaporation, precipitation, river runoff, and ice formation or melting cause significant variations in salinity. These variations are often most evident in coastal areas and marginal seas. The combination of temperature and salinity variations leads to changes in seawater density. Seawater density

1568-529: A wide range of sessile animals (e.g. mussels , starfish , barnacles ) and various kinds of seaweeds . In physical oceanography , a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore, representing the intertidal zone where there is one. Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of 1–50 m (3.3–164.0 ft). According to an atlas prepared by

1666-439: Is a bus terminal named Anandabazar Bus Terminal. This is one of the largest and densely populated area of Halishahar Thana. It is under 11 No. Ward of Chittagong City Corporation . Famous BDR field / Home ground of Bengali Kheloyar , SOS, Central Mosque, and some primary schools are situated here. This is the largest and densely populated area of Halishahar Thana. It is under 26 No. Ward of Chittagong City Corporation . Most of

1764-541: Is a coastline that has experienced a fall in sea level, because of either a global sea-level change, or local uplift. Emergent coastlines are identifiable by the coastal landforms , which are above the high tide mark, such as raised beaches . In contrast, a submergent coastline is one where the sea level has risen, due to a global sea-level change, local subsidence , or isostatic rebound . Submergent coastlines are identifiable by their submerged, or "drowned" landforms, such as rias (drowned valleys) and fjords According to

1862-457: Is a sub field of Fluid dynamics describing flows occurring on spatial and temporal scales that are greatly influenced by the Coriolis force . Roughly 97% of the planet's water is in its oceans, and the oceans are the source of the vast majority of water vapor that condenses in the atmosphere and falls as rain or snow on the continents. The tremendous heat capacity of the oceans moderates

1960-476: Is a turbulent and complex system which utilizes atmospheric measurement techniques such as eddy covariance to measure the rate of heat transfer expressed in the unit of or petawatts . Heat flux is the flow of energy per unit of area per unit of time. Most of the Earth's heat storage is within its seas with smaller fractions of the heat transfer in processes such as evaporation, radiation, diffusion, or absorption into

2058-425: Is adjacent to I block. H block falls under Ward No. 25. This Chittagong Division location article is a stub . You can help Misplaced Pages by expanding it . Coastal A coast  – also called the coastline , shoreline , or seashore  – is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake . Coasts are influenced by

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2156-528: Is connected to marine pollution which can occur from a number of sources: Marine debris (garbage and industrial debris); the transportation of petroleum in tankers , increasing the probability of large oil spills ; small oil spills created by large and small vessels, which flush bilge water into the ocean. Marine pollution occurs when substances used or spread by humans, such as industrial , agricultural and residential waste , particles , noise , excess carbon dioxide or invasive organisms enter

2254-707: Is entrained into the Circumpolar Current, and can be traced into the Indian and Pacific basins. Flow from the Arctic Ocean Basin into the Pacific, however, is blocked by the narrow shallows of the Bering Strait . Also see marine geology about that explores the geology of the ocean floor including plate tectonics that create deep ocean trenches. An idealised subtropical ocean basin forced by winds circling around

2352-415: Is extremely important to geologists. These provide vital clues for reconstructing the geography of ancient continents ( paleogeography ). The locations of these beds show the extent of ancient seas at particular points in geological time, and provide clues to the magnitudes of tides in the distant past. Sediments deposited in the shoreface are preserved as lenses of sandstone in which the upper part of

2450-457: Is formed in polar regions where cold salty waters sink in fairly restricted areas. This is the beginning of the thermohaline circulation . Oceanic currents are largely driven by the surface wind stress; hence the large-scale atmospheric circulation is important to understanding the ocean circulation. The Hadley circulation leads to Easterly winds in the tropics and Westerlies in mid-latitudes. This leads to slow equatorward flow throughout most of

2548-408: Is more important. Macrotidal coasts lack barrier islands and lagoons , and are characterized by funnel-shaped estuaries containing sand ridges aligned with tidal currents. Wave action is much more important for determining bedforms of sediments deposited along mesotidal and microtidal coasts than in macrotidal coasts. Waves erode coastline as they break on shore releasing their energy; the larger

2646-423: Is moved along the coastline by the waves. This forms an abrasion or cliffed coast . Sediment deposited by rivers is the dominant influence on the amount of sediment located in the case of coastlines that have estuaries. Today, riverine deposition at the coast is often blocked by dams and other human regulatory devices, which remove the sediment from the stream by causing it to be deposited inland. Coral reefs are

2744-483: Is one of the smallest and not overcrowded area of Halishahar Thana. It is under 11 No. South Kattally Ward (Ctg. City Corporation) of Chittagong . It has only 4 lanes. J Block is situated at east side of Halishahar Housing Estate Field . Address: J Block, Halishahar Housing Estate, Chittagong, Bangladesh. Coordinates: 22.3413, 91.7821. H block is a relatively smaller area in Halishahar and probably most quieter too. It

2842-499: Is primarily influenced by both these factors—colder, saltier water is denser than warmer, fresher water. This variation in density creates stratification in the ocean and is key to understanding ocean circulation patterns. Understanding the complex interactions between temperature, salinity, and density is essential for predicting ocean circulation patterns, climate change effects, and the health of marine ecosystems. These factors also influence marine life, as many species are sensitive to

2940-442: Is that the phase velocity of each individual wave always has a westward component, but the group velocity can be in any direction. Usually the shorter Rossby waves have an eastward group velocity and the longer ones have a westward group velocity. The interaction of ocean circulation, which serves as a type of heat pump , and biological effects such as the concentration of carbon dioxide can result in global climate changes on

3038-412: Is the counterintuitive observation that the coastline of a landmass does not have a well-defined length. This results from the fractal curve –like properties of coastlines; i.e., the fact that a coastline typically has a fractal dimension . Although the "paradox of length" was previously noted by Hugo Steinhaus , the first systematic study of this phenomenon was by Lewis Fry Richardson , and it

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3136-462: Is the study of physical conditions and physical processes within the ocean , especially the motions and physical properties of ocean waters. Physical oceanography is one of several sub-domains into which oceanography is divided. Others include biological , chemical and geological oceanography. Physical oceanography may be subdivided into descriptive and dynamical physical oceanography. Descriptive physical oceanography seeks to research

3234-456: The Aegean Sea . The following articles describe some coastal landforms: "Coastal waters" (or "coastal seas") is a rather general term used differently in different contexts, ranging geographically from the waters within a few kilometers of the coast, through to the entire continental shelf which may stretch for more than a hundred kilometers from land. Thus the term coastal waters is used in

3332-596: The Norwegian Sea evaporative cooling is predominant, and the sinking water mass, the North Atlantic Deep Water (NADW), fills the basin and spills southwards through crevasses in the submarine sills that connect Greenland , Iceland and Britain . It then flows along the western boundary of the Atlantic with some part of the flow moving eastward along the equator and then poleward into the ocean basins. The NADW

3430-585: The Southern Ocean about every eight years. Since it is a wave-2 phenomenon (there are two peaks and two troughs in a latitude circle ) at each fixed point in space a signal with a period of four years is seen. The wave moves eastward in the direction of the Antarctic Circumpolar Current . Among the most important ocean currents are the: The ocean body surrounding the Antarctic is currently

3528-617: The Southern Ocean is of concern to ocean scientists because bottom water changes will effect currents, nutrients, and biota elsewhere. The international awareness of global warming has focused scientific research on this topic since the 1988 creation of the Intergovernmental Panel on Climate Change . Improved ocean observation, instrumentation, theory, and funding has increased scientific reporting on regional and global issues related to heat. Tide gauges and satellite altimetry suggest an increase in sea level of 1.5–3 mm/yr over

3626-452: The US EPA considers this region to extend much further offshore. "Coastal waters" has specific meanings in the context of commercial coastal shipping , and somewhat different meanings in the context of naval littoral warfare . Oceanographers and marine biologists have yet other takes. Coastal waters have a wide range of marine habitats from enclosed estuaries to the open waters of

3724-610: The United Nations , about 44% of the human population lives within 150 km (93 mi) of the sea as of 2013 . Due to its importance in society and its high population concentrations, the coast is important for major parts of the global food and economic system, and they provide many ecosystem services to humankind. For example, important human activities happen in port cities. Coastal fisheries (commercial, recreational, and subsistence) and aquaculture are major economic activities and create jobs, livelihoods, and protein for

3822-670: The Western Interior Seaway , a shallow sea that flooded central North America during the late Cretaceous Period (about 100 to 66 million years ago). These are beautifully exposed along the Book Cliffs of Utah and Colorado . The following articles describe the various geologic processes that affect a coastal zone: Larger animals that live in coastal areas include puffins , sea turtles and rockhopper penguins , among many others. Sea snails and various kinds of barnacles live on rocky coasts and scavenge on food deposited by

3920-471: The continents . Their major restoring force is the change in Coriolis force with latitude . Their wave amplitudes are usually in the tens of meters and very large wavelengths . They are usually found at low or mid latitudes. There are two types of Rossby waves, barotropic and baroclinic . Barotropic Rossby waves have the highest speeds and do not vary vertically. Baroclinic Rossby waves are much slower. The special identifying feature of Rossby waves

4018-417: The convergence zones debris, foam and seaweed accumulates, while at the divergence zones plankton are caught and carried to the surface. If there are many plankton in the divergence zone fish are often attracted to feed on them. At the ocean-atmosphere interface, the ocean and atmosphere exchange fluxes of heat, moisture and momentum. The important heat terms at the surface are the sensible heat flux ,

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4116-469: The ocean and cause harmful effects there. The majority of this waste (80%) comes from land-based activity, although marine transportation significantly contributes as well. It is a combination of chemicals and trash, most of which comes from land sources and is washed or blown into the ocean. This pollution results in damage to the environment, to the health of all organisms, and to economic structures worldwide. Since most inputs come from land, either via

4214-596: The ocean . Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping . Naturally occurring debris, such as driftwood and drift seeds , are also present. With the increasing use of plastic , human influence has become an issue as many types of (petrochemical) plastics do not biodegrade quickly, as would natural or organic materials. The largest single type of plastic pollution (~10%) and majority of large plastic in

4312-444: The rivers , sewage or the atmosphere, it means that continental shelves are more vulnerable to pollution. Air pollution is also a contributing factor by carrying off iron, carbonic acid, nitrogen , silicon, sulfur, pesticides or dust particles into the ocean. The pollution often comes from nonpoint sources such as agricultural runoff , wind-blown debris , and dust. These nonpoint sources are largely due to runoff that enters

4410-795: The topography of the surrounding landscape, as well as by water induced erosion , such as waves . The geological composition of rock and soil dictates the type of shore that is created. Earth contains roughly 620,000 km (390,000 mi) of coastline. Coasts are important zones in natural ecosystems , often home to a wide range of biodiversity . On land, they harbor important ecosystems such as freshwater or estuarine wetlands , which are important for bird populations and other terrestrial animals . In wave-protected areas, they harbor salt marshes , mangroves or seagrasses , all of which can provide nursery habitat for fin fish , shellfish , and other aquatic animals . Rocky shores are usually found along exposed coasts and provide habitat for

4508-693: The East Greenland and Labrador currents, in the Atlantic and the Oyashio . They are forced by winds circulation around low pressure (cyclonic). The Gulf Stream, together with its northern extension, North Atlantic Current , is a powerful, warm, and swift Atlantic Ocean current that originates in the Gulf of Mexico , exits through the Strait of Florida, and follows the eastern coastlines of the United States and Newfoundland to

4606-736: The French use the term "Riviera" to refer to the Italian Riviera and call the French portion the "Côte d'Azur". As a result of the fame of the Ligurian rivieras, the term came into English to refer to any shoreline, especially one that is sunny, topographically diverse and popular with tourists. Such places using the term include the Australian Riviera in Queensland and the Turkish Riviera along

4704-534: The United Nations has declared 2021–2030 the UN Decade on Ecosystem Restoration , but restoration of coastal ecosystems has received insufficient attention. Since coasts are constantly changing, a coastline's exact perimeter cannot be determined; this measurement challenge is called the coastline paradox . The term coastal zone is used to refer to a region where interactions of sea and land processes occur. Both

4802-571: The average sea level rose by 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s. This was faster than the sea level had ever risen over at least the past 3,000 years. The rate accelerated to 4.62 mm (0.182 in)/yr for the decade 2013–2022. Climate change due to human activities is the main cause. Between 1993 and 2018, melting ice sheets and glaciers accounted for 44% of sea level rise , with another 42% resulting from thermal expansion of water . International attention to address

4900-408: The average elevation of Earth's landmasses is only 840 metres (2,760 ft), while the ocean's average depth is 3,800 metres (12,500 ft). Though this apparent discrepancy is great, for both land and sea, the respective extremes such as mountains and trenches are rare. Because the vast majority of the world ocean's volume is deep water, the mean temperature of seawater is low; roughly 75% of

4998-417: The average wind wave and swell conditions are relatively mild. Low energy coasts typically change slowly, and tend to be depositional environments. High energy coasts are exposed to the direct impact of waves and storms, and are generally erosional environments. High energy storm events can make large changes to a coastline, and can move significant amounts of sediment over a short period, sometimes changing

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5096-461: The coast of Wales and other countries. Coastal fish , also called inshore fish or neritic fish, inhabit the sea between the shoreline and the edge of the continental shelf . Since the continental shelf is usually less than 200 metres (660 ft) deep, it follows that pelagic coastal fish are generally epipelagic fish , inhabiting the sunlit epipelagic zone . Coastal fish can be contrasted with oceanic fish or offshore fish , which inhabit

5194-812: The coast. Estuarine and marine coastal ecosystems are both marine ecosystems . Together, these ecosystems perform the four categories of ecosystem services in a variety of ways: The provisioning services include forest products, marine products, fresh water , raw materials, biochemical and genetic resources. Regulating services include carbon sequestration (contributing to climate change mitigation ) as well as waste treatment and disease regulation and buffer zones. Supporting services of coastal ecosystems include nutrient cycling , biologically mediated habitats and primary production . Cultural services of coastal ecosystems include inspirational aspects, recreation and tourism , science and education. According to one principle of classification, an emergent coastline

5292-567: The continental shelf. Similarly, the term littoral zone has no single definition. It is the part of a sea , lake , or river that is close to the shore . In coastal environments, the littoral zone extends from the high water mark , which is rarely inundated, to shoreline areas that are permanently submerged . Coastal waters can be threatened by coastal eutrophication and harmful algal blooms . The identification of bodies of rock formed from sediments deposited in shoreline and nearshore environments (shoreline and nearshore facies )

5390-555: The deep seas beyond the continental shelves. Many coastal areas are famous for their kelp beds. Kelp is a fast-growing seaweed that can grow up to half a meter a day in ideal conditions. Mangroves , seagrasses , macroalgal beds, and salt marsh are important coastal vegetation types in tropical and temperate environments respectively. Restinga is another type of coastal vegetation. Coasts also face many human-induced environmental impacts and coastal development hazards . The most important ones are: The pollution of coastlines

5488-564: The direction of travel of the layers of water slowly move farther and farther to the right as they get deeper in the Northern Hemisphere, and to the left in the Southern Hemisphere. In most cases, the very bottom layer of water affected by the wind is at a depth of 100 m – 150 m and is traveling about 180 degrees, completely opposite of the direction that the wind is blowing. Overall, the net transport of water would be 90 degrees from

5586-414: The east in the Northern and Southern hemispheres , using the equator as a guide . Kelvin waves are known to have very high speeds, typically around 2–3 meters per second. They have wavelengths of thousands of kilometers and amplitudes in the tens of meters. Rossby waves , or planetary waves are huge, slow waves generated in the troposphere by temperature differences between the ocean and

5684-502: The equator towards the poles, thereby reducing the temperature gradients that would exist in the absence of fluid motion. Perhaps three quarters of this heat is carried in the atmosphere; the rest is carried in the ocean. The atmosphere is heated from below, which leads to convection, the largest expression of which is the Hadley circulation . By contrast the ocean is heated from above, which tends to suppress convection. Instead ocean deep water

5782-777: The human uses of the coast and threaten coastal ecosystems. The interactive effects of climate change, habitat destruction , overfishing , and water pollution (especially eutrophication ) have led to the demise of coastal ecosystem around the globe. This has resulted in population collapse of fisheries stocks, loss of biodiversity , increased invasion of alien species , and loss of healthy habitats. International attention to these issues has been captured in Sustainable Development Goal 14 "Life Below Water", which sets goals for international policy focused on preserving marine coastal ecosystems and supporting more sustainable economic practices for coastal communities. Likewise,

5880-463: The impact of these natural cycles on the lifestyle and livelihood of Native Hawaiians tending coastal fishponds. Aia ke ola ka hana meaning . . . Life is in labor . Tidal resonance occurs in the Bay of Fundy since the time it takes for a large wave to travel from the mouth of the bay to the opposite end, then reflect and travel back to the mouth of the bay coincides with the tidal rhythm producing

5978-426: The latent heat flux, the incoming solar radiation and the balance of long-wave ( infrared ) radiation . In general, the tropical oceans will tend to show a net gain of heat, and the polar oceans a net loss, the result of a net transfer of energy polewards in the oceans. The oceans' large heat capacity moderates the climate of areas adjacent to the oceans, leading to a maritime climate at such locations. This can be

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6076-410: The majority of coastal human populations. Other coastal spaces like beaches and seaside resorts generate large revenues through tourism . Marine coastal ecosystems can also provide protection against sea level rise and tsunamis . In many countries, mangroves are the primary source of wood for fuel (e.g. charcoal ) and building material. Coastal ecosystems like mangroves and seagrasses have

6174-621: The margins of the continental shelves , make up about 7 percent of the Earth's oceans, but at least 85% of commercially harvested fish depend on coastal environments during at least part of their life cycle. As of October 2010, about 2.86% of exclusive economic zones were part of marine protected areas . The definition of coasts varies. Marine scientists think of the "wet" (aquatic or intertidal ) vegetated habitats as being coastal ecosystems (including seagrass, salt marsh etc.) whilst some terrestrial scientists might only think of coastal ecosystems as purely terrestrial plants that live close to

6272-587: The microplastics go through the water filtration system and into the ocean, but because of their small size they are likely to escape capture by the preliminary treatment screens on wastewater plants. These beads are harmful to the organisms in the ocean, especially filter feeders, because they can easily ingest the plastic and become sick. The microplastics are such a concern because it is difficult to clean them up due to their size, so humans can try to avoid using these harmful plastics by purchasing products that use environmentally safe exfoliates. Between 1901 and 2018,

6370-507: The more resistant rocks erode more slowly, remaining as headlands or outcroppings . Parts of a coastline can be categorised as high energy coast or low energy coast. The distinguishing characteristics of a high energy coast are that the average wave energy is relatively high so that erosion of small grained material tends to exceed deposition, and consequently landforms like cliffs, headlands and wave-cut terraces develop. Low energy coasts are generally sheltered from waves, or in regions where

6468-472: The net transport of surface water 90 degrees to the right of the wind in the Northern Hemisphere, and 90 degrees to the left of the wind in the Southern Hemisphere. As the wind blows across the surface of the ocean, it "grabs" onto a thin layer of the surface water. In turn, that thin sheet of water transfers motion energy to the thin layer of water under it, and so on. However, because of the Coriolis Effect,

6566-592: The northeast before crossing the Atlantic Ocean. The Kuroshio Current is an ocean current found in the western Pacific Ocean off the east coast of Taiwan and flowing northeastward past Japan , where it merges with the easterly drift of the North Pacific Current . It is analogous to the Gulf Stream in the Atlantic Ocean, transporting warm, tropical water northward towards the polar region. Ocean heat flux

6664-535: The northern hemisphere the land masses prevent this and the ocean circulation is broken into smaller gyres in the Atlantic and Pacific basins. The Coriolis effect results in a deflection of fluid flows (to the right in the Northern Hemisphere and left in the Southern Hemisphere). This has profound effects on the flow of the oceans. In particular it means the flow goes around high and low pressure systems, permitting them to persist for long periods of time. As

6762-528: The ocean surface, by the presence of the waves, changes the wind near the surface. The ocean can gain moisture from rainfall , or lose it through evaporation . Evaporative loss leaves the ocean saltier; the Mediterranean and Persian Gulf for example have strong evaporative loss; the resulting plume of dense salty water may be traced through the Straits of Gibraltar into the Atlantic Ocean . At one time, it

6860-406: The ocean through observations and complex numerical models, which describe the fluid motions as precisely as possible. Dynamical physical oceanography focuses primarily upon the processes that govern the motion of fluids with emphasis upon theoretical research and numerical models. These are part of the large field of Geophysical Fluid Dynamics (GFD) that is shared together with meteorology . GFD

6958-441: The ocean through rivers, but wind-blown debris and dust can also play a role, as these pollutants can settle into waterways and oceans. Pathways of pollution include direct discharge, land runoff, ship pollution , bilge pollution , atmospheric pollution and, potentially, deep sea mining . Marine debris , also known as marine litter, is human-created solid material that has deliberately or accidentally been released in seas or

7056-405: The ocean's volume has a temperature from 0° – 5 °C (Pinet 1996). The same percentage falls in a salinity range between 34 and 35 ppt (3.4–3.5%) (Pinet 1996). There is still quite a bit of variation, however. Surface temperatures can range from below freezing near the poles to 35 °C in restricted tropical seas, while salinity can vary from 10 to 41 ppt (1.0–4.1%). The vertical structure of

7154-485: The oceans is discarded and lost nets from the fishing industry. Waterborne plastic poses a serious threat to fish , seabirds , marine reptiles , and marine mammals , as well as to boats and coasts. A growing concern regarding plastic pollution in the marine ecosystem is the use of microplastics. Microplastics are beads of plastic less than 5 millimeters wide, and they are commonly found in hand soaps, face cleansers, and other exfoliators. When these products are used,

7252-517: The only continuous body of water where there is a wide latitude band of open water. It interconnects the Atlantic , Pacific and Indian oceans, and provide an uninterrupted stretch for the prevailing westerly winds to significantly increase wave amplitudes. It is generally accepted that these prevailing winds are primarily responsible for the circumpolar current transport. This current is now thought to vary with time, possibly in an oscillatory manner. In

7350-497: The orbital motion of the Moon results in tidal patterns that vary over the course of a month. The ebb and flow of the tides produce a cyclical current along the coast, and the strength of this current can be quite dramatic along narrow estuaries. Incoming tides can also produce a tidal bore along a river or narrow bay as the water flow against the current results in a wave on the surface. Tide and Current (Wyban 1992) clearly illustrates

7448-524: The original direction of the wind. Langmuir circulation results in the occurrence of thin, visible stripes, called windrows on the surface of the ocean parallel to the direction that the wind is blowing. If the wind is blowing with more than 3 m s , it can create parallel windrows alternating upwelling and downwelling about 5–300 m apart. These windrows are created by adjacent ovular water cells (extending to about 6 m (20 ft) deep) alternating rotating clockwise and counterclockwise. In

7546-452: The past 100 years. The IPCC predicts that by 2081–2100, global warming will lead to a sea level rise of 260 to 820 mm. The rise and fall of the oceans due to tidal effects is a key influence upon the coastal areas. Ocean tides on the planet Earth are created by the gravitational effects of the Sun and Moon . The tides produced by these two bodies are roughly comparable in magnitude, but

7644-431: The people here were migrated from Sandwip , Comilla , Noakhali . Halishahar Police Station, North Halishahar Post Office, Baitul Karim Madrasha Complex, Darussunnah Madrasha, B-Block primary school, Ananda Pathshala, Halishahar Public School & College, Halishahar Housing Estate School, Halishahar Mahila College, Bihari Graveyard, Bihari centre, Central Eid-Gah (Shapla Math), S-Club Circle E.T.C are situated here. This

7742-429: The planet's climate , and its absorption of various gases affects the composition of the atmosphere . The ocean's influence extends even to the composition of volcanic rocks through seafloor metamorphism , as well as to that of volcanic gases and magmas created at subduction zones . From sea level, the oceans are far deeper than the continents are tall; examination of the Earth's hypsographic curve shows that

7840-420: The point of view of the ocean, the atmosphere imposes a significant wind stress on its surface, and this forces large-scale currents in the ocean. Through the wind stress, the wind generates ocean surface waves ; the longer waves have a phase velocity tending towards the wind speed . Momentum of the surface winds is transferred into the energy flux by the ocean surface waves. The increased roughness of

7938-416: The sandstone is coarser than the lower part (a coarsening upwards sequence ). Geologists refer to these are parasequences . Each records an episode of retreat of the ocean from the shoreline over a period of 10,000 to 1,000,000 years. These often show laminations reflecting various kinds of tidal cycles. Some of the best-studied shoreline deposits in the world are found along the former western shore of

8036-498: The sea floor. The majority of the ocean heat flux is through advection or the movement of the ocean's currents. For example, the majority of the warm water movement in the south Atlantic is thought to have originated in the Indian Ocean. Another example of advection is the nonequatorial Pacific heating which results from subsurface processes related to atmospheric anticlines. Recent warming observations of Antarctic bottom water in

8134-579: The sea. Some coastal animals are used to humans in developed areas, such as dolphins and seagulls who eat food thrown for them by tourists. Since the coastal areas are all part of the littoral zone , there is a profusion of marine life found just off-coast, including sessile animals such as corals , sponges, starfish, mussels, seaweeds, fishes, and sea anemones . There are many kinds of seabirds on various coasts. These include pelicans and cormorants , who join up with terns and oystercatchers to forage for fish and shellfish. There are sea lions on

8232-401: The seashore (see also estuaries and coastal ecosystems ). While there is general agreement in the scientific community regarding the definition of coast, in the political sphere, the delineation of the extents of a coast differ according to jurisdiction . Government authorities in various countries may define coast differently for economic and social policy reasons. The coastline paradox

8330-427: The second principle of classification, a concordant coastline is a coastline where bands of different rock types run parallel to the shore. These rock types are usually of varying resistance , so the coastline forms distinctive landforms, such as coves. Discordant coastlines feature distinctive landforms because the rocks are eroded by the ocean waves . The less resistant rocks erode faster, creating inlets or bay ;

8428-404: The slope than up it. Steep waves that are close together and break with the surf plunging down onto the shore slope expend much of their energy lifting the sediment. The weak swash does not carry it far up the slope, and the strong backwash carries it further down the slope, where it either settles in deeper water or is carried along the shore by a longshore current induced by an angled approach of

8526-486: The specific temperature and salinity ranges of their habitats. Energy for the ocean circulation (and for the atmospheric circulation) comes from solar radiation and gravitational energy from the Sun and Moon. The amount of sunlight absorbed at the surface varies strongly with latitude, being greater at the equator than at the poles, and this engenders fluid motion in both the atmosphere and ocean that acts to redistribute heat from

8624-437: The temperature can be divided into three basic layers, a surface mixed layer , where gradients are low, a thermocline where gradients are high, and a poorly stratified abyss. In terms of temperature, the ocean's layers are highly latitude -dependent; the thermocline is pronounced in the tropics, but nonexistent in polar waters (Marshak 2001). The halocline usually lies near the surface, where evaporation raises salinity in

8722-747: The terms coast and coastal are often used to describe a geographic location or region located on a coastline (e.g., New Zealand's West Coast , or the East , West , and Gulf Coast of the United States .) Coasts with a narrow continental shelf that are close to the open ocean are called pelagic coast , while other coasts are more sheltered coast in a gulf or bay . A shore , on the other hand, may refer to parts of land adjoining any large body of water, including oceans (sea shore) and lakes (lake shore). The Earth has approximately 620,000 kilometres (390,000 mi) of coastline. Coastal habitats, which extend to

8820-492: The threats of coasts has been captured in Sustainable Development Goal 14 "Life Below Water" which sets goals for international policy focused on preserving marine coastal ecosystems and supporting more sustainable economic practices for coastal communities. Likewise, the United Nations has declared 2021–2030 the UN Decade on Ecosystem Restoration , but restoration of coastal ecosystems has received insufficient attention. Physical oceanography Physical oceanography

8918-650: The tropics, or meltwater dilutes it in polar regions. These variations of salinity and temperature with depth change the density of the seawater, creating the pycnocline . The temperature of ocean water varies significantly across different regions and depths. As mentioned, the vast majority of ocean water (around 75%) lies between 0° and 5°C, mostly in the deep ocean, where sunlight does not penetrate. The surface layers, however, experience far greater variability. In polar regions, surface temperatures can drop below freezing, while in tropical and subtropical regions, they may reach up to 35°C. This thermal stratification results in

9016-487: The wave the more energy it releases and the more sediment it moves. Coastlines with longer shores have more room for the waves to disperse their energy, while coasts with cliffs and short shore faces give little room for the wave energy to be dispersed. In these areas, the wave energy breaking against the cliffs is higher, and air and water are compressed into cracks in the rock, forcing the rock apart, breaking it down. Sediment deposited by waves comes from eroded cliff faces and

9114-476: The wave-front to the shore. These waves which erode the beach are called destructive waves. Low waves that are further apart and break by spilling , expend more of their energy in the swash which carries particles up the beach, leaving less energy for the backwash to transport them downslope, with a net constrictive influence on the beach. Riviera is an Italian word for "shoreline", ultimately derived from Latin ripa ("riverbank"). It came to be applied as

9212-407: The waves surge up the river estuaries from the ocean. Geologists classify coasts on the basis of tidal range into macrotidal coasts with a tidal range greater than 4 m (13 ft); mesotidal coasts with a tidal range of 2 to 4 m (6.6 to 13 ft); and microtidal coasts with a tidal range of less than 2 m (7 ft). The distinction between macrotidal and mesotidal coasts

9310-406: The whole ocean system are ultimately connected, although certain regional classifications are useful and relevant. The waters of the continental shelves represent such a region. The term "coastal waters" has been used in a wide variety of different ways in different contexts. In European Union environmental management it extends from the coast to just a few nautical miles while in the United States

9408-482: The world's people live in coastal regions. According to a United Nations atlas, 44% of all people live within 150 km (93 mi) of the sea. Many major cities are on or near good harbors and have port facilities. Some landlocked places have achieved port status by building canals . Nations defend their coasts against military invaders, smugglers and illegal migrants. Fixed coastal defenses have long been erected in many nations, and coastal countries typically have

9506-534: Was believed that evaporation / precipitation was a major driver of ocean currents; it is now known to be only a very minor factor. A Kelvin wave is any progressive wave that is channeled between two boundaries or opposing forces (usually between the Coriolis force and a coastline or the equator ). There are two types, coastal and equatorial. Kelvin waves are gravity driven and non-dispersive . This means that Kelvin waves can retain their shape and direction over long periods of time. They are usually created by

9604-441: Was expanded upon by Benoit Mandelbrot . Tides often determine the range over which sediment is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges produce deposition at a smaller elevation interval. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however, tidal bores can erode as

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