Chapter 2 Key Concepts

The world’s oceans can be divided into open oceans and marginal seas.
The oceans share four main topographic features: the continental shelf, continental slope, the deep-sea floor, and oceanic ridge systems.
The earth’s crust is in continual motion, and the main topographic features of the ocean reflect this motion
Many of the ocean’s major features are due to the unique set of chemical and physical properties of water, including its dissolving power, high specific heat, transparency, and heat of vaporization.
Seawater temperature is regulated primarily by solar energy input and the mixing of other water.
Salinity is a measure of the dissolved inorganic solids in seawater.
Oxygen is added to seawater by mixing with the atmosphere and by photosynthesis; it is lost by respiration and by chemical oxidation of various compounds.
Restriction of vertical and horizontal water circulation often tips the balance toward low oxygen concentration.
Environmental light originates mainly from the sun and is therefore strongest in surface waters.
Surface oceanic currents are controlled by the interaction of the planetary wind system and the earth’s rotation.
The earth’s rotation causes a deflection in surface current direction called the Coriolis effect, which affects water flow on many geographic scales.
The major oceanic surface currents are determined by the planetary wind systems modified by the Coriolis effect.
Western ocean boundary currents are caused by winds combined with the earth’s rotation and result in large- scale transport of surface water from the tropics to higher latitudes.
Eddies of meandering parts of boundary currents may form cold-core and warm-core rings.
Winds and the Coriolis effect combine to cause upwelling, which brings nutrient-rich deeper water to the surface.
Extraordinarily strong surface water motion is generated by storms and earthquakes.
Small-scale changes in current systems, combined with latitudinal temperature change and coastal irregularities, may isolate adjacent coastal regions.
Seawater density, an important property affecting the vertical movement of water, is controlled mainly by salinity and temperature.
Vertical circulation and deep-water circulation are regulated primarily by differences in water density, where higher-density water is generated at the surface, usually at high latitudes, followed by sinking and travel at depth to lower latitudes.
The surface and deep ocean are connected by means of a global conveyor belt circulation.
Wind moving over the water surface sets up a series of wave patterns, which cause oscillatory water motion beneath.
Waves are defined by their period, wave length, wave height, and velocity as well as by the water depth.
As a wave approaches the shore, it becomes affected by the presence of the bottom when the depth is less than L/2; then the wave eventually breaks.
Shorelines greatly alter the pattern of waves and currents.
The coast may be soft sediment or outcrops of rock under active erosion.
Gravitational effects of the moon and sun, modulated by the earth’s rotation and basin shape, cause periodic tides.
Estuaries are coastal bodies of water where water of the open sea mixes with fresh water from a river.