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32 Cards in this Set
- Front
- Back
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Water Breakdown Earth
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Most abundant chemical compound near Earth's surface covering 70%.
97.6% in oceans 2.4% freshwater |
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Hydrologic Cycle
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The cycle of evaporation and precipitation that controls the distribution of Earth's Water
Water evaporates from bodies of water Water vapor is transported by moving air masses (clouds) Water returns to Earth as precipitation |
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Freshwater
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Precipitation is the basic freshwater source
2/3 returns to atmosphere remaining 1/3 is runoff flowing downhill or groundwater absorbed into surface |
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Groundwater
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the water that resides in a saturation zone - percolates downward from surface - 25 x larger supply than surface freshwater - often within 100 m of surface
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Aquifer
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a zone of water bearing rock through which groundwater can flow
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Infiltration
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absorption of water by the ground
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Permeability
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the ease with which fluids flow through porous sediment and rock
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Runoff
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Precipitation not absorbed by the ground that moves over Earths surface
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Watershed
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the area of land that drains into a stream
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Water Table
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the upper boundary of the saturated zone
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Saturation zone vs. Aquifer
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Saturation Zone may consist of water-bearing but impermeable rock or sediments such as clay.
Aquifers have high porosity and high permeability |
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Surface Water
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collectively the water in streams ponds lakes and reservoirs
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Continental divide separates
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watersheds draining into opposite sides of a continent
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Artesian Aquifer
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confined under pressure from water at higher elevation
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Freshwater Usage
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average US usage is 5700 liters per person per day (1500 gal)
agriculture production of electricity industrial domestic |
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Oceans
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continuous body of salt water covering Earth's surface
3 regions - Pacific - largest w/greatest depth - Atlantic 2nd in size - the Indian w/smallest surface area |
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Seas
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A maller region distinguished by special characteristics - bound by land - ex. Mediterranean, Gulf of Mexico and Caribbean seas
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Nature of Seawater - Salinity
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does not change water temp with air temp. averages 35%
Concentration increased by evap and ice formation Decreased by heavy precipitation |
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Movement of seawater
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mixing time - a complete mixing every 2000 years
1.5 million X's over 3 billion years two types of motion - waves and currents |
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Waves
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simplest structure: moving crests and troughs
wave height is the vertical distance from trough to crest Wave length is the horizontal distance between two successive crests wave period - time between passage of two successive crests |
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Ocean waves from Wind
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characteristics depend on 3 factors
wind speed length of time wind blows Fetch - distance the wind blows across the open ocean |
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Small waves vs. large waves
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small waves dissipate from friction with the water
large waves last longer travel faster and eventually coalesce into swell |
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Swells
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Carry energy but do not transport water
individual particle motions are circular - diameter=wave height whitecaps form when top of swell is toppled by wind |
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Refraction
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shoreward side of wave slows & wafe front bends toward shore
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Breakers
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at depth less than the wave height, lower part slows and top part breaks forward
surf - breaker formation zone |
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Undertow
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direct return of water under the breakers
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longshore currents
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motion parallel to the shore
produces rip tides upon entering a channel |
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Rip Current
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strong stream of water pushing out against the waves -
usually extends beyond surf zone then diminishes indicators - lack of surf, darker water, turbid steak of water |
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Ocean Currents
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streams transporting water over large oceanic distance along roughly the same path
produced by density differences in seawater and winds blowing persistently in the same direction |
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Density Currents
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denser water displace less dens water in deeper basins
3 influences water temp salinity suspended sediments |
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surface currents
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global circulation patterns maintained basically by patterns of prevailing winds
influenced by rotation of Earth, ocean basin shapes and Gyres |
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Ocean Floor
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Continental shelf - eroded margin relatively shallow water
Continental slope - steeper transition Ocean Basin - deepest part of ocean - flat abyssal plain w/ mountainous ridges |
