Chemical and Physical Features of the Ocean

1
Chemical and Physical Features of the Ocean
2
Water - the chemical features

• You probably know water's chemical description is
  H2O.
• The hydrogen atoms are "attached" to one side of
  the oxygen atom, resulting in a water molecule
  having a positive charge on the side where the
  hydrogen atoms are and a negative charge on the
  other side, where the oxygen atom is.
• The bonds joining atoms in a water molecule are
  said to be polar covalent.
• Since opposite electrical charges attract, water
  molecules tend to attract each other, making
  water kind of "sticky."

3
Picture of a water molecule
4

• Water is called the universal solvent because it
  dissolves more substances than any other liquid.
• This means that wherever water goes, either
  through the ground or through our bodies, it
  takes along valuable chemicals, minerals, gases,
  and nutrients.

5
Water - the physical features

• Water is unique in that it is the only natural
  substance that is found in all three states -
  liquid, solid (ice), and gas (steam) -- at the
  temperatures normally found on Earth. Earth's
  water is constantly interacting, changing, and in
  movement

6

• Water freezes at 32 Fahrenheit (F) and boils at
  212 F.
• In fact, water's freezing and boiling points are
  the baseline with which temperature is measured
  0 on the Celsius scale is water's freezing
  point, and 100 is water's boiling point.
• Water is unusual in that the solid form, ice, is
  less dense than the liquid form, which is why ice
  floats.

7

• Water possesses a high specific heat index.
• This means that water can absorb a lot of heat
  before it begins to get hot.
• The high specific heat index of water also helps
  regulate the rate at which air changes
  temperature, which is why the temperature change
  between seasons is gradual rather than sudden,
  especially near the oceans.

8
Wind Patterns

• The trade winds are a pattern of wind that are
  found in bands around the Earth's equatorial
  region.
• The trade winds are the prevailing winds in the
  tropics, blowing from the high-pressure area in
  the horse latitudes towards the low-pressure area
  around the equator.
• The trade winds blow predominantly from the
  northeast in the northern hemisphere and from the
  southeast in the southern hemisphere.

9
Global Ocean Circulation

• Ocean circulation is the large scale movement of
  waters in the ocean basins.
• Winds drive surface circulation, and the cooling
  and sinking of waters in the polar regions drive
  deep circulation.

10
Coriolis Effect

• Due to the rotation of the earth, currents are
  deflected to the right in the northern hemisphere
  and to the left in the southern hemisphere.

11
(No Transcript)
12

• Surface circulation carries the warm upper waters
  pole-ward from the tropics. Heat is released
  along the way from the waters to the atmosphere.
• Surface circulation also carries the cooler
  waters from the poles toward the tropics.

13

• This is what controls the weather

14
Underwater circulation

• As opposed to wind-driven currents the
  thermohaline circulation is that part of the
  ocean circulation which is driven by density
  differences.
• Sea water density depends on temperature and
  salinity, hence the name thermohaline.

15
Three - layered ocean

• Due to density differences the ocean is divided
  in to three layers
• Surface layer (mixed layer) about 100 -200
  meters thick
• Intermediate layer from the bottom of the
  surface layer to about 1000 meters
• Deep layer from the intermediate to the bottom

16
The thermohaline circulation consists of

• Deep water formation the sinking of water
  masses. Deep water formation takes place in a few
  localized areas the Greenland-Norwegian Sea, the
  Labrador Sea, the Mediteranean Sea, the Wedell
  Sea, the Ross Sea.
• Spreading of deep waters mainly as deep western
  boundary currents
• Upwelling of deep waters- It is thought to take
  place mainly in the Antarctic Circumpolar Current
  region, possibly aided by the wind.

17

• The salinity and temperature differences arise
  from heating/cooling at the sea surface and from
  the surface freshwater fluxes (evaporation and
  sea ice formation enhance salinity
  precipitation, runoff and ice-melt decrease
  salinity).

18
(No Transcript)
19
(No Transcript)
20
Tides

• Tides are the cyclic rising and falling of
  Earth's ocean surface caused by the tidal forces
  of the Moon and the Sun acting on the oceans.

21
Reason for tides

• The gravitational attraction of the moon causes
  the oceans to bulge out in the direction of the
  moon. Another bulge occurs on the opposite side
  due to centripetal force.
• Tides are created because the Earth and the moon
  are attracted to each other, just like magnets
  are attracted to each other.

22

• The moon tries to pull at anything on the Earth
  to bring it closer. But, the Earth is able to
  hold onto everything except the water. Since the
  water is always moving, the Earth cannot hold
  onto it, and the moon is able to pull at it.
• As the moon travels around the earth and as they,
  together, travel around the sun, the combined
  gravitational forces cause the world's oceans to
  rise and fall.
• Since the earth is rotating while this is
  happening, two tides occur each day. The ocean is
  constantly moving from high tide to low tide, and
  then back to high tide. There is about 12 hours
  and 25 minutes between the two high tides

23
Two types of tides
24
Spring tides

• When the moon is full or new, the gravitational
  pull of the moon and sun are combined. At these
  times, the high tides are very high and the low
  tides are very low.
• They occur when the Earth, the Sun, and the Moon
  are in a line. The gravitational forces of the
  Moon and the Sun both contribute to the tides.

25
Neap Tides

• During the moon's quarter phases the sun and moon
  work at right angles, causing the bulges to
  cancel each other.
• The result is a smaller difference between high
  and low tides

26
Bay of Fundy
27
Waves

• The wind not only drives surface currents, it
  causes waves.
• Highest part of wave crest
• Lowest part of wave - trough
• Size of wave height (measured from trough to
  crest)
• Distance between waves wavelength
• Time it takes to go by a given point period
• Distance over water that wind travels fetch

28
Fetch

• Wave height is a function of fetch and wind
  strength.
• Around Antarctica, the wind is able to create
  large waves because there is unlimited fetch.

29

• Some waves undergo a phenomenon called
  "breaking". A breaking wave is one whose base can
  no longer support its top, causing it to
  collapse. A wave breaks when it runs into shallow
  water, or when two wave systems oppose and
  combine forces.

30
I love waves