Chapter 24. Earth’s Water. Water on Earth. Water is the most abundant chemical compound near the surface of the earth. It covers about 70% of the earth’s surface.
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Estimates of the distribution
of water found on earth’s
Groundwater slowly moves underground, and some of it emerges in streambeds,
Keeping the streams running during dry spells.
The approximate watersheds of the Columbia River, the Colorado River, and the
There is really only one ocean.
Salinity is defined as the mass of salts dissolved in 1.0 kg (1000 g) of seawater.
This corresponds to 35 0/00 (35 parts per thousand)
As a pattern of swell approaches a gently sloping beach the friction between
the circular motion of the water particles and the bottom slows the wave, and
the wave front becomes steeper and steeper. When the depth is about
one and one third times the wave height, the wave breaks forward, moving water
towards the beach.
Breakers result in a buildup of water along the beach that moves horizontally along the
beach as a longshore current. Where it finds a shore bottom that allows it to return to
the sea it surges out in a strong flow called a rip current.
Colder surface waters near Greenland more dense.
More dense water sinks to join even more dense water from Antarctica.
Surface currents – set up by winds.
Continental shelf – part of continent that retains some of the same features. Gradual slope. Use to be above sea level.
Continental slope – steep feature connecting shelf to deep ocean basin.
Ocean basin – bottom of ocean floor containing an abyssal plain, ridges, trenches and seamounts.
Deepest part of ocean floor found in trenches.
# 1, 2, 3, 5, 7, 8, 9, 12, 20
More water is evaporated from the ocean than is returned by precipitation. More water is precipitated over the land than evaporates. The difference is returned to the ocean by rivers and streams.
Precipitation can evaporate again (70%), become runoff (streams) (30%) or groundwater (1%).
The watershed of a large river includes all the water sheds of the smaller streams that feed into the large river. Two adjacent watersheds re separated by a line called a divide. A continental divide separates river systems that drain into opposite sides of the continent.
Water moving downhill is sometimes stopped by a depression in a watershed, where water collects in a pond or a lake,a natural depression or in an artificial dam. If these accumulations of water are used for water storage, flood control, or to generate electricity they are called a reservoir.
There is only one continuous ocean with parts that have been given names. A seais a smaller part of the ocean or an inland body of salty water.
Pacific ocean is deepest and largest and has rim of fire. The Atlantic ocean is shallowest and second largest. It has the mid Atlantic ridge. The Indian ocean is smallest and as deep as the Pacific. The Atlantic has shallow seas: Gulf of Mexico, Caribbean, Mediterranean.
Na+ and Cl- are most prevalent ions in the ocean. Salinity is the mass of ions per 1 kg of seawater. It increases by evaporation of the water and formation of sea ice. It decreases by heavy precipitation, the melting of ice, and the addition of freshwater by a large river.
Two types of motion on the surface of the ocean: waves that have been produced by some disturbance and have crests and troughs, and currents, which move water from one place to another. An ocean wave can be described by the wave height, the wavelength, and the wave period.
Waves formed by wind speed, length of time and fetch. The wind blows in different directions and wave patterns are complex especially during storm. Eventually become swells.
Swells have circular patterns becoming smaller as you go down and then stopping. They touch the ocean bottom as they reach shore and breakers are created at the surf.
Water that returns to the sea by moving beneath the breakers creates an undertow. Water that moves parallel to the shore in the surf zone is a longshore current. A rip current is a strong stream of water that bursts out against the waves and returns water to the sea.
Adensity currentis an ocean current that flows because of density differences due to differences in temperature, salinity, and suspended sediments. The current originates because of bodies of water with distinct properties moving towards each other. Surface currents are set up by winds.
The continental shelf is gently steeping, below the ocean water but shallower and used to be continent. It is followed by the steeper continental slope.
There are also canyons along the continental slope and there are ridges and trenches at some places in the ocean floor.Summary