map
T Road oday - Chap. 6& 7
H our test #3 - Dec. 2
Chapter 6 Water and Ocean Structure Key Ideas:
* Water is a polar molecule (H2O). * Water occurs naturally on Earth as a solid, a liquid, and a gas. * The thermal properties of water (heat capacity) are responsible for the mild climate conditions on Earths surface. * Water density is greatly affected by both temperature and salinity (vertical structure of the ocean and mixing behavior). * Light and sound travel differently in water than they do in air.
The Miracle Molecule
Water is a polar molecule, having a positive and a negative side
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106o
What holds water molecules together?
Hydrogen bonds
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Water And Heat
Heat Capacity is a measure of the heat required to raise the temperature of 1g of a substance by 1C. Water has a very high heat capacity, which means it resists changing temperature when heat is added or removed. Specific heat capacity of water is larger than soil,so the rise of temperature is less for water, all other things being equal. But, there's another effect: Sun's energy penetrates farther into water than it does into earth, so the temperature rise per square meter of exposed surface is less for water.
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Water Temperature And Density
Why ice floats in your rum & coke!
Water Temperature And Density
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The arrangement of water molecules in an ice crystal.
Global Thermostatic Effects
The energy input or output associated with water in the three states of matter
Global Thermostatic Effects
The unique thermal properties of water are responsible for the mild conditions on Earth. Waters thermostatic effects allow living things to flourish on Earth.
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For more, check out http://oceanmotion.org/
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Chapter 7 Seawater Chemistry
Why are the oceans salty? What controls the salinity of the oceans?
Key Ideas in Chapter 7
* Water is a polar molecule with the remarkable ability to dissolve more substances than any other natural solvent. * Salinity is the measure of dissolved inorganic solids in water. * The most abundant ions dissolved in seawater are chloride, sodium and sulfate. * The ocean is in chemical equilibrium(steady state) acquired over billions years. * Nitrogen and oxygen are the most abundant gases dissolved in seawater (but as gases, do not contribute to salinity).
Why are the oceans salty?
Whats missing?
For weathering interactive go to:
http://eesc.columbia.edu/courses/ees/slides/climate/weathering/index.htm
The Components of Salinity
The most abundant components of a kilogram of seawater.
The Dissolving Power of Water
Water is a polar molecule, having a positive and a negative side. The polarity of water molecules causes ionic compounds to dissolve.
The ions of sodium and chloride in NaCl (table salt) are held together by ionic bonds, electrostatic attraction that exists between ions that have opposite charge.
The Dissolving Power of Water
As solid sodium chloride dissolves, the positive and negative ions are attracted to the positive and negative ends of the polar water molecules.
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What you cant see
is the salt dissolving!
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The Principle of Constant Proportions
Forchhammers principle states that although the salinity of various samples of seawater may vary, the ratio of major salts is constant. Forchhammers principle is also known as the principle of constant proportions.
The ocean is in chemical equilibrium
Determining Salinity
Salinity can be determined measuring by the chlorinity of the sample. Since the chlorinity is easy to measure, and the principle of constant proportions applies to all seawater, scientists can use the following formula to determine salinity: Salinity (in parts per thousand) = 1.80655 chlorinity (in parts per thousand)
ppt
or
o
/oo
or
PSU (practical salinity units)
refractometer
25
Salinity values (amount of salt)
15 0
Refractive I ndex
50 40 35 30 25 20 15 10 0
24
Salinity
(24 grams of salt)
CTD - conductivity, temperature, depth
Chemical Equilibrium
Is the ocean becoming progressively saltier with age? No, the ocean is in chemical equilibrium. The proportion and amounts of dissolved solids remain constant. This concept is known as the steady state ocean.
Ions are being added to and removed from the ocean at the same rate.
Residence Time
Residence time is the average length of time an element spends in the ocean. Residence time can be calculated by the equation: Residence Time = Amount of element in the ocean The rate at which the element is added to or removed from the ocean
The residence time of any element depends on its chemical activity.
Residence Time
What controls the salinity of the oceans?
Volcanism (outgasing)
calcification silicification
hydrothermal
Conservative and Non-conservative Constituents
Conservative constituents of seawater are those constituents that occur in constant proportions. Conservative elements have long residence times and are the most abundant dissolved material in the ocean.
Conservative and Non-conservative Constituents
Conservative constituents of seawater are those constituents that occur in constant proportions. Conservative elements have long residence times and are the most abundant dissolved material in the ocean. Nonconservative constituents have short residence times, and are usually associated with seasonal, biological or short geological cycles.
What controls the salinity of the oceans?
Volcanism (outgasing)
calcification silicification
Weathering
hydrothermal
What controls the salinity of the oceans?
Evaporation Precipitation Runoff Sea ice formation Mixing (circulation) Why isnt the ocean completely mixed? What controls the pattern of salinity?
What controls the pattern of salinity? Why is this important?
http://science.hq.nasa.gov/oceans/physical/SSS.html
Why is this important?
http://www.ldeo.columbia.edu/edu/dees/ees/clim ate/slides/ocean_index.html
Temperature, Salinity, & Water Density
1.027335
Temperature, Salinity, & Water Density
= density gm/cm3 1.027335
sigma-T T = ( 1) x 1000
Temperature, Salinity, & Water Density
Density ( )of average seawater = 1.027335 gm/cm3
T = ( 1) x 1000 T = ( 1 .0 2 7 3 3 5 1) x 1000 = 2 7 .
335 1 .0 2 5 4 2 5 3 52 5 .4 2 5 3 5
T
Why is this important?
T & S Structure of the Ocean
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http://www.windows.ucar.edu
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Density Structure of the Ocean
The ocean is divided into three density zones: The surface zone - the upper layer of the ocean, containing the least dense water. The surface zone is only about 2% of total ocean volume. The pycnocline - a zone in which density increases with depth, containing about 18% of all ocean water The deep zone contains about 80% of all ocean water. There is little change in density throughout this layer.
2002 Brooks/Cole, a division of Thomson Learning, Inc.
Density Structure of the Ocean
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Gr. puknos - thick, dense Density stratification of the ocean Pycnocline - the region of the water column characterized by the strongest vertical change in density with depth. 2002 Brooks/Cole, a division of Thomson Usually temperature falls and salinity rises in this zone. Learning, Inc.
Why is this important?
http://www.ldeo.columbia.edu/edu/dees/ees/clim ate/slides/ocean_index.html
Why does this pattern exist?
Water Masses Age
Windows to the Universe (http://windows.ucar.edu/