The Oceans

Section 1: Exploring the OceanPg. 350

Oceans

• Since ancient times, Oceans have provided many things:– Food– Trade Routes– Habitats

Exploring the Floor

• Bathymetry: is the study of depth contours on the ocean floor.

• Sonar has allowed recent scientists a better way to study these contours.– (SOund Navigation And Ranging)

SONAR

• A ship uses an underwater Speaker• This speaker sends out a soundwave, or Ping• Scientists listen to a receiver and wait for the

sound wave to return. • By studying the length of time it takes and the

way the sound returns, scientists can determine how the ocean floor is shaped.

Shallow Water

• Consists of 2 parts:– Continental Shelf: The area of gently sloping,

shallow water that extends from the edge of the continent

– Continental slope: The incline just beyond the continental shelf…Slopes into deeper water.

Open Ocean

• Consists of 2 areas:– The Abyssal Plain is an area of smooth, flat land of

the ocean floor. It is covered with thick layers of mud and silt.

– The Mid-Ocean Ridge is a mountain range that winds through all the oceans. Remember, this is the area where seafloor spreading occurs.

Deepest Depths

• Recall: Deep ocean trenches are areas where subduction takes place.

• These Trenches are canyons on the ocean floor where the ocean is so deep you can’t seen the bottom of the ocean.

Ocean Zones

• Intertidal Zone: Area from highest tide to the point exposed during low tide.

• Neritic Zone: Is the area from low tide to the edge of the continental shelf.

• Open Ocean Zone: Is the area past the continental shelf that extends into deeper parts of the ocean.

Waves

• Waves move energy through the water• THEY DO NOT MOVE THINGS

• They form from winds blowing across the surface. These winds move energy to the water, creating a wave

• Size of the Wave Depends on:– Strength of the wind (Stronger wind=bigger wave)– Length of time the wind blows (Longer

time=bigger wave)– Distance the wind blows (Longer distance=bigger

wave)

Energy

• As energy moves through the water, the water remains in place

• Particles in the water move in circles with the energy of the wave, but they do not move forward with the wave.

Wave Characteristics

• Wavelength: the distance between the waves

• Frequency: The number of waves that pass a point in a set time

• Wave Height: How high the wave is. Strength of the wave depends on how high the wave is…

Types of Waves

• Breakers: White capped waves that crash or “break” near the shore– Wave height increases as the wave nears the

shore, causing the top to get heavy.• Tsunamis: Waves that are created when

earthquakes occur under the water– These are more common in the Pacific ocean, but

not all happen there.

Affects on the Shore

• Longshore Drifts– Water washes onto the beach at an angle, but when it retreats, it

runs strait down the beach. – As the waves slow down, they deposit the sand, creating a long

ridge called a sandbar.

• Rip Currents– Occur when a sandbar traps water in a groove between it and the

shore.– When the water breaks through, it creates a strong current flowing

back to sea.– Swimmers can escape rip currents by swimming parallel to the shore

until they can overcome the current and swim inland.

Erosion on Beaches

• Barrier Beaches– A natural landform that form when long sand

deposits form parallel to the shore. – These are separated from the shore by a small

body of water called a Lagoon– These beaches protection the shoreline from wave

erosion along low-lying beaches.

• Sand Dunes– Hills of windblown sand – Plants grown in the dunes, producing roots which

prevent erosion by holding the sand in place.– Dune plants can be destroyed, causing the dune to

be easily washed away.

• Groins – Areas of rock built by humans to reduce erosion.– Groins move water, increasing erosion further

down the beach.

SECTION 3: TIDESPg. 366

Tides

• Tides are when the water on the coast rises and falls….

• When high point is reached: High tide• When low point is reached: Low tide

• They are caused by the relationship between the sun, moon, and earth

Daily Tides

• Tides rotate through every 24 hours• Tides occur every 12 hours and 25 mins apart

in any location.

• 2 high tides/2 low tides each day…

Monthly Tides

• Sun pulls water on earth’s surface toward it

• Changes in the positions of the Earth, moon, and sun affect height during months

Tides

• Spring Tide– Occurs 2x a month– Has the greatest difference between high & Low Tide– Occurs because the sun and moon are lined up,

combining their gravitational pull

• Neap Tide– Occurs 2x a month– Happens when the sun and moon are at right angles to

each other– Has least difference between high and low tide.

OCEAN WATER CHEMISTRYSection 4: Pg. 372

Salinity (level of salt)

• 1 Kg of ocean water contains 35 grams of salts

• 2 substances of greatest content (86% of salinity)– Sodium (Na)– Chlorine (Cl)

• Salt comes from volcanic eruptions thousands of years ago that spewed chemicals into the oceans. The chemicals broke apart into the ions we know as salt.

Effects of Salinity

• Salinity can vary in various oceans. • It is higher in colder climates where ice will

freeze as freshwater, leaving the salt behind in the leftover ocean water.

• Freezing Point: Ocean water freezes at -1.9 degrees Celsius– Slat interferes with ice crystals, causing the water

to freeze slower.

• Salt water has a higher density than freshwater---Why would you think that?– It has more particles in the same space.

Temperature

• Ocean gets it’s heat from the sun

• Warm water is less dense, causing it to remain on the top

• As you get deeper, the water gets colder and denser.

Gases

• Carbon Dioxide and Oxygen are found in ocean water

• Carbon dioxide is 60% more available in the oceans than in air

• Oxygen is more available near the surface---it comes from the air around the surface– Amount of oxygen is affected by temperature..

Cold Water allows for more oxygen than warm.

• Figure 19 Pg. 376

• What 2 factors affect temperature of ocean water?????

• Salinity & Density

Temperature & Pressure

• As you go deeper in the ocean, temperature decreases and pressure increases

• How does this compare with the earth?

• To overcome these 2 variables, scientists use a Submersible, which is an underwater vehicle built to withstand pressure.

CURRENTS & CLIMATESection 5

Currents

• A large stream of water that moves through oceans– As the earth rotates, it causes the winds to circle around,

therefore the currents go in a circle rather than in a strait line.• This is called the Coriolis Effect

• Surface Currents----affect water at the surface (up to 100 meters deep) are caused by wind– They can cool the air above the ocean, causing changes to

the climate in the area

Climate

• The pattern of temperature and precipitation typical of an area over a long period of time.

• Currents move cold and warm water around the globe affecting climate.

• El Nino: is an abnormal climate event that occurs every 2-7 years in the Pacific ocean.

Upwellings

• The movement of cold water upward from deep in the ocean.

• Warm surface water is blown away by the wind, and the cold water comes to the surface to replace it.

• Upwellings bring up tiny ocean organisms, minerals, and other nutrients that replenish the nutrients at the surface of the ocean.