Oceans S6E3: Recognize the significant role of water on earth processes. E.Q.: What are characteristics of oceans, and why are oceans important?

Composition and Structure of Earth’s Oceans Why are oceans salty? What does the seafloor look like? How do temperature, salinity, and density affect ocean structure?

Salinity The “saltiness” or dissolved content of a body of water.

Seawater Water from the sea or ocean. Has an average salinity of 3.5 % If you had a 1000 grams of seawater, 35 grams of it would be salts and the rest pure water

brackish Freshwater mixed with seawater. Lagoons

Abyssal plain Large, flat areas of the seafloor that extend across the deepest parts of the ocean basins.

Earth’s Oceans The Pacific Ocean-Largest and deepest ocean. Larger than all of Earth’s combined land areas. The Atlantic Ocean-half the size of the Pacific. Occupies about 20% of Earth’s surface. The Indian Ocean-Between Africa, India, and the Indonesian Islands. Third largest ocean.

Earth’s Oceans The Southern Ocean-Surrounds Anarctica. The fourth largest ocean. Ice covers some its surface all year. The Arctic Ocean-Near the North Pole. Smallest and shallowest Ocean. Ice covers some of its surface all year.

Formation of the Oceans The Earth’s oceans began to form around 4.2 billion years ago. Ancient volcanic eruptions added water vapor and other gases to the atmosphere. As early Earth cooled, the water vapor condensed and rain fell for tens of thousands of years, collecting in basin that became oceans.

Formation of the Oceans Asteroids and comets were a second source of water for Earth’s oceans. The melted ice from these objects added to the water filling the Earth’s ocean basin. As tectonic plates move, new oceans form and old oceans disappear. The volume of oceans has remained fairly constant since oceans first formed.

Composition of Seawater The rain that fell to Earth’s surface billions of years ago washed over rocks and dissolved minerals. The minerals contained substances that formed salts. Rivers and streams carried these substances to the ocean basins which made the oceans salty.

Composition of Seawater

The Seafloor What does the seafloor look like? Continental Margins-Part of an ocean basin next to a continent. Extends from shoreline to the deep ocean. Divided into continental shelf (shallow), continental slope (steep), and the continental rise (at the base of the slope).

The Seafloor Abyssal plains-large flat areas of the seafloor that extend across the deepest parts of the ocean basin. Thick layers of sediment Some underwater volcanoes.

The Seafloor Mid-ocean Ridges-Places on the seafloor where tectonic plates pull apart and volcanic mountains form. Ocean trenches-areas where an oceanic tectonic plate collides with a continental plate and forms a deep canyon or trench. Trenches are the deepest parts of the ocean.

The Seafloor Scientist use submersibles and other technologies to explore the seafloor. The seafloor contains valuable resources. Two main categories of resources are energy and minerals. Energy resources-oil, natural gas, and methane. Mineral resources-manganese, gold, and zinc.

Zones in the Ocean Oceans are divided into regions or zones based on characteristics that include amount of sunlight, temperature, salinity, and density. Surface zone-shallow area of seawater that gets the most sunlight. Middle zone-Receives only faint blue-green light. Deep zone-No light. Plants do not grow. Some animals make their own light.

Zones in the Ocean Amount of sunlight

Ocean Layers Temperature, salinity, and density vary with depth. Sometimes these characteristics can change quickly within a short change in depth which creates distinctive layers of seawater.

Lesson 2: Ocean Waves and Tides Essential Questions: What causes ocean waves? What cause tides?

tsunami A wave that forms when an ocean disturbance suddenly moves a large volume of water. In other words, a really big wave caused by earthquake, landslide, or volcanic eruption.

Sea level The average level of the ocean’s surface at any given time.

tide Periodic rise and fall of the ocean’s surface caused by the gravitational force between the Earth and Moon, and between the Earth and Sun.

Tidal range The difference in water level between a high tide and a low tide.

Spring tide Has the largest tidal range and occurs when Earth, the Moon, and the Sun form a straightline.

Neap tide Has the lowest tidal range and occurs when Earth, the Moon, and the Sun form a right angle.

Parts of a Wave Crest-the highest part of a wave. Trough-the lowest part of a wave. Wavelength-the distance from crest to crest.

Surface Waves Wind causes these waves to roll onto a beach. Range in size from tiny ripples to huge waves several meters high. Three factors affect size of surface waves. Wind speed, time, and distance.

Wave Motion Waves transport water particles in a circular pattern. As depth increases, the circular motion decreases. At the wave base, wave motion stops. Wave base is equal to ½ the wavelength of the wave above.

Wave Motion

When Surface Waves Reach Shore As a wave moves into shallow water, it changes shape and size. As the base of the wave drags on the seafloor, its speed decreases, the wavelength shortens, and the height increases. When the wave gets too high for the wave base to support the crest, it collapses, or breaks.

Tsunamis Tsunamis have a short wave height. Usually less than 30 cm high, but the wavelength can be hundreds of kilometers long. Water from a tsunami just keeps coming and can cause much damage. A 2004 tsunami in the Indian Ocean killed more than 225,000 people in 11 countries and destroyed entire villages. http://video.nationalgeographic.com/video/101-videos/tsunami-101

Tides The gravitational force between the Moon and Earth causes tides. The largest tides occur in an area when the Moon is directly facing the area or directly opposite Coastlines, shape and size of the ocean basin, and depth of the ocean affect tide.

Tides The Moon is full or new during a spring tide. High and low tides occur during neap tides and spring tides, however the range between high and low tides is less during a neap tide.

Lesson 3: Ocean Currents Essential Questions What are the major types of ocean current? How do ocean currents affect weather and climate?

Ocean Current A large volume of water flowing in a certain direction

Gyre A circular system of currents.

Coriolis effect The movement of wind and water to the right or left that is caused by Earths’ rotation

Upwelling The vertical movement of water toward the ocean’s surface.

Major Ocean Currents Surface Currents-form when wind blows over water and the moving air particles drag on the surface and cause the water to move. A gyre is a circular system of surface currents. Gyre move in different directions because of the Coriolis Effect.

Major Ocean Currents Surface Currents-form when wind blows over water and the moving air particles drag on the surface and cause the water to move. A gyre is a circular system of surface currents. Gyre move in different directions because of the Coriolis Effect.

Major Ocean Currents Surface currents move water horizontally across the ocean’s surface, but upwelling currents move water vertically toward the ocean’s surface. Density currents move cold water from the ocean surface to deeper parts of the ocean.

Impacts on Weather and Climate A system of surface currents and density currents that distributes thermal energy around Earth. The Gulf Stream is a warm-water current. The California Current is a cold-water current.

Impacts on Weather and Climate

Impacts on Weather and Climate The Great Ocean Conveyor Belt slowly moves water around the globe. Warm surface currents and cold density currents interacting to distribute thermal energy.

Lesson 4: Environmental Impacts on Oceans How does pollution affect marine organisms? How does global climate change affect marine ecosystems? Why is it important to keep oceans healthy?

marine Refers to anything related to the ocean.

Harmful algal blooms An explosive growth of algae that harms organisms.

Coral bleaching Loss of color in corals that occurs when stressed corals expel the algae that live in them.

Ocean Pollution Sources of pollution Runoff from land Airborne pollutants that start over land. Spill from shipping Dumping trash Offshore mining and drilling for resources.

Effects of Ocean Pollution Cause problems for marine organisms. Excess sediments can clog filtering structures of filter feeders and block light so that photosynthesizing organisms die. Excess nitrates cause algae blooms that can kill fish that eat them. Some algae blooms use up all the oxygen in the water and fish can’t get the oxygen they need.

Oceans and Global Climate Change Effects of increasing temperature Effects of increasing carbon dioxide Choral bleaching Glaciers and ice sheets melt adding more water to the oceans, raising sea level. The warmer the water, the less O2 and organisms die. CO2 combines with seawater to create Carbonic Acid which lowers the pH level of the water. This causes the ocean to become more acidic. Acidity can cause shells and skeletons of organisms to weaken or dissolve.

Keeping Oceans Healthy Earth’s oceans stabilize Earth systems and provide many resources to humans. It’s important to keep oceans healthy because they distribute moisture and thermal energy. Marine algae produce oxygen for our atmosphere. Oceans provide resources for humans and habitat for marine organisms.