Oceanography

Oceanography EMT 322Lecture note IFederal University, Dutse.Introduction Oceanography, the science of sea, is a subject of modern growth though its foundations can be traced back to the earliest times. It is concerned with the elucidation of many intricate and complex problems of physical and biological nature and practical problems of sea which form so large a part of the environment of mankind.Definition As an interdisciplinary subject it is been define by so manybased on their perspectives.Oceanography, the science of the oceans, embraces primarily study the form and nature of the oceanic basins, the characteristics of the waters in these basins and the movements to which these waters are subject toand like other sciences now-a-days, it is growing on the technical contributions.Interdisciplinary Oceanography

Cont,Geology: sea floor tectonics, coastal processes, sediments and hydrological cycles.Geography: wind belt, weather, coastal landforms and world climate.Biology; fisheries, ecological surveys, microbiology and marine adaptations.Chemistry: dissolved components, temperature dependences stratification/density and chemical tracers.Physics: currents, waves, sonar, thermal properties of water.Astronomy: tidal forces, oceans on other planets, origin of water, origin of life.Others: ocean engineering, marine archeology, and marine policySea and the Oceans Smaller and shallower than an ocean (this is why the arctic ocean might be more appropriately considered a sea)Composed of salt water (although some inland seas, such as Caspian sea in Asia, are actually large lakes with relatively high salinity)Somewhat enclosed by land (but some seas, such as the Sargasso sea in the Atlantic ocean, are defined by strong ocean currents rather by land)Directly connected to the oceans. The seven SeasThe Red SeaThe Mediterranean SeaThe Persian gulf SeaThe Black SeaThe Adriatic SeaThe Caspian SeaThe Indian sea/Arabia seaOCEANS

#the deepest area of ocean is 11,022mtrs (Mariana trench) while on land the highest point is Mt. Everest 8850mtrs#NameAverage Depth/height Relative ocean size Pacific Ocean3940mtrs50.1%Atlantic Ocean3844mtrs26.0%Indian Ocean3840mtrs20.5%Arctic Ocean1117mtrs3.40%Origin of the oceansOriginally, earth had no oceans, the oceans (and atmosphere) came from inside earth as a result of outgassing. Their origin is directly linked to the origin of the atmosphere, at least 4 billion years ago.From the Nebular hypothesis, a huge cloud of dust and gasses (a nebular) contracts, most of the material is gravitationally swept toward the center, producing the sun, while the remainder flattens into the disk,Cont,Small eddies are created by the circular motion, in time most of the remaining debris forms the planets and their moons.

Cont,After the formation of planets, widespread volcanic activity released large amounts of water vapor (H2O) and smaller quantities of other gases, as Earth cooled, the water vapor condensed into clouds and fell to Earths surface, where it accumulated to form the oceans.

Ocean water chemistry (70.8% of Earths surface)Waters remarkable properties help make life as we know it possible on Earth. These properties include the arrangement of its atoms, how its molecules stick together, its ability to dissolves almost everything, and its heat storage capacity.The water molecule is composed of one atom of oxygen and two atoms of hydrogen (H2O). The two hydrogen atoms that are covalently bonded to the oxygen atom, are attached to the same side of the oxygen atom and produce a bend in the geometry of a water molecule.Cont, this geometry makes water molecules polar, which allows them to form Hydrogen bonds with other water molecules or other substances and give water it remarkable properties. Water for example, is the universal solvent because it can hydrate charged particles (ions), thereby dissolving them.

Cont,

Cont,Water is one of the few substances that exits naturally on Earth in all three states of matter (solid, liquid, gas).

Cont,Hydrogen bonding gives water unusually thermal properties, such as a high freezing point 00C and boiling point 100oC.

Cont, a high heat capacity and high specific heat (1 calorie per gram), a high latent heat of melting (80 calories per gram), and high latent heat of vaporization (540 calories per gram). Waters high heat capacity and latent heats have important implications in regulating global thermostatic effects.

Other properties The density of water increases as temperature decreases, similar to most substances, and reaches a maximum density at 4oC. Below 4oC, however, water density decreases with temperature, due to the formation of bulky ice crystals. As water freezes, it expands by 9% in volume, so ice floats on water.

Cont,The physical properties of pure water and sea water are remarkably similar, with a few notable exception. Compared to pure water, sea water has a higher pH, density, and boiling point (but lower freezing point).We shall discuss salinity in our subsequent lectures .

Acknowledgement Essentials of oceanography 10th edition by Alan P.Oceanography for Geographers by Sharma &Vatal