Volcanoes%20and%20Igneous%20Activity%20%20Earth%20%20-%20%20Chapter%204 - PowerPoint PPT Presentation

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Volcanoes%20and%20Igneous%20Activity%20%20Earth%20%20-%20%20Chapter%204

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Title: Volcanoes%20and%20Igneous%20Activity%20%20Earth%20%20-%20%20Chapter%204


1
Marine Hydrology
  • Topics
  • Oceanography
  • Main oceans
  • Properties of seawater
  • Composition
  • Salinity
  • Sources of sea salt
  • Density
  • Factors that impact density
  • Temperature
  • Cold water vs. warm water
  • Layers of temperature

2
14.1 The Vast World Ocean
? Nearly 71 percent of Earths surface is covered
by the global ocean.
? Oceanography is a science that draws on the
methods and knowledge of geology, chemistry,
physics, and biology to study all aspects of
world oceans.
3
14.1 The Vast World Ocean
? The world ocean can be divided into four main
ocean basins
  • The Pacific Ocean is the largest and deepest
  • The Atlantic Ocean is about half the size of the
    Pacific and not quite as deep.
  • The Indian Ocean, largely a southern hemisphere
    body, is slightly smaller than the Atlantic.
  • The Arctic Ocean is the smallest and about 7 of
    the size of the Pacific.

4
15.1 The Composition of Seawater
? Salinity is the total amount of dissolved solid
material in water.
  • Because the proportion of dissolved substances in
    seawater is so small, oceanographers express
    salinity as
  • parts per thousand (ppt)
  • Ex 35g of salt per 1000 grams of water 35 o/oo

5
Percentage of dissolved salts
? Most of the salt in seawater is sodium
chloride, NaCl
  • Average seawater salinity
  • 35o/oo
  • 30.6 Sodium (Na)
  • 55.0 Chloride (Cl)
  • 14.4 Other

6
15.1 The Composition of Seawater
? Sources of Sea Salt
1) Chemical weathering and erosion of rocks on
the continents
2) Earths interior- volcanic activity
7
15.1 The Composition of Seawater
? Processes Affecting Salinity
Processes that decrease salinity
- Precipitation
- Sea ice melting
- Icebergs melting
- Runoff from land
Processes that increase salinity
- Evaporation
- Formation of sea ice
8
Processes that impact salinity
9
15.1 The Composition of Seawater
? The oceans surface water temperature depends
on the amount of solar radiation received, which
is primarily a function of latitude.
10
? Temperature Variation with Depth
  • The thermocline is the layer of ocean water
    between about 300 meters and 1000 meters where
    there is a rapid change of temperature with depth.

11
Variations in Ocean Surface Temperature
12
Variations in Ocean Water Temperature
13
15.1 The Composition of Seawater
? Density is defined as mass per unit volume. It
can be thought of as a measure of how heavy
something is for its size.
? Factors Affecting Seawater Density
Seawater density is influenced by two main
factors salinity and temperature.
14
15.1 The Composition of Seawater
? Density Variation with Depth
The pycnocline is the layer of ocean water
between about 300 meters and 1000 meters where
there is a rapid change of density with depth.
15
Variations in Ocean Water Density
16
? Oceanographers generally recognize a
three-layered structure in most parts of the open
ocean a shallow surface mixed zone, a transition
zone, and a deep zone.
? Surface Zone
Shallow (300 to 450 meters)
Zone of mixing
Sun-warmed zone
17
15.1 The Composition of Seawater
? Transition Zone
Between surface layer and deep zone
Thermocline and pycnocline
? Deep Zone
Sunlight never reaches this zone.
Temperatures are just a few degrees above
freezing.
Constant high-density water
18
Ocean Zones
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