Title: Volcanoes%20and%20Igneous%20Activity%20%20Earth%20%20-%20%20Chapter%204
1Marine 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
214.1 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.
314.1 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.
415.1 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
5Percentage 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
615.1 The Composition of Seawater
? Sources of Sea Salt
1) Chemical weathering and erosion of rocks on
the continents
2) Earths interior- volcanic activity
715.1 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
8Processes that impact salinity
915.1 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.
11Variations in Ocean Surface Temperature
12Variations in Ocean Water Temperature
1315.1 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.
1415.1 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.
15Variations 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
1715.1 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
18Ocean Zones