Science Unit 5: Oceanography Flashcards
Define/Describe: Continental Shelf
A gently sloping shallow area of the ocean floor that extends outward from the edge of a continent. (Likely where you swim when you go to the beach)
Define/Describe: Continental Slope
Located at the edge of the continental shelf; this slope is the beginning of the big drop-off to the ocean floor
Define/Describe: Abyssal Plains
Flat, smooth, broad part of the ocean floor covered with thick layers of mud & silt; covers about half of our ocean floors
Define/Describe: Pelagic Division
Open ocean waters; upper layers allow phytoplankton to photosynthesize where they can get sunlight; free swimming animals would be found here
Define/Describe: Benthic Division
Area of the ocean nearest the ocean floor; bottom dwelling animals would be found here
Define/Describe: Mid-ocean Ridge
Long chains of mountains along the ocean floor stretching through all the world’s oceans for 49,700 miles; along the ridges, lava erupts and forms new ocean floor
Define/Describe: Seamount
Underwater hills/mountains; they were once active underwater volcanoes
Define/Describe: Guyot
Seamounts whose tops have been destroyed by erosion, which gives them a flattened shape at the top
Define/Describe: Trench
A long, deep valley/canyon on the ocean floor through which old ocean floor sinks back toward the mantle; they are the deepest parts of the ocean and the lowest points on Earth
Identify factors that limit our ability to explore the ocean floor
Submersibles cannot go that deep due to increased pressure (deeper = more pressure)
Define Salinity
The measure of the amount of salt dissolved in water
Identify average % of salt in seawater
3.5%
What % of Earth’s water is saltwater?
Roughly 97%
What is the % of salinity of brackish water?
1.5 to 3.4% (Less than seawater)
List two factors that cause salinity to decrease
Spring floods
Where fresh water meets salty water
How can salinity increase?
Salinity can increase:
in hot dry climates as the water evaporates and leaves the salt behind
near the poles when water freezes and leaves the slat behind
How can salinity decrease?
Salinity can decrease:
- near the surface of the water as the dense salty water sinks
- in places where fresh and saltwater mix
Identify 4 most abundant elements in seawater
Hydrogen; Oxygen; Sodium; Chloride
Describe how salinity affects density
Fresh water is less dense than saltwater. Saltwater will sink, fresh water will float. Salt water is denser than fresh water, even with a temperature change.
Describe how temperature affects density
Cold water is denser than warm water. Cold will sink, warm will float.
Explain relationship between depth, temperature, and pressure
As depth increases, temperature decreases and water pressure increases.
Define/Describe: Wave
A forward motion of energy through water
Define/Describe: Breakers
White-capped waves crashing on the shore
Define/Describe: Tsunami
A giant wave usually caused by an earthquake beneath the ocean floor
Define/Describe: Currents
Large streams of water that flow through the ocean
Define/Describe: Surface Currents (What are they caused by?)
Currents that affect water to a depth of several hundred meters (close to top/surface), caused mainly by wind. Cold surface currents cause moderate (mild) climates in coastal areas
Define/Describe: Deep Currents (What are they caused by?)
Also density currents; deeper than surface currents; caused by the differences in the density of ocean water; these currents move and mix water around the world
Define/Describe: Upwellings (How do they affect sea life?)
The upward movement of cold water from the ocean depths; they force up cold water, tiny ocean organisms, and minerals, and increases the supply of nutrients in the ocean
Define/Describe: El Niño
An abnormal climate event that occurs every two to seven years in the Pacific Ocean, causing changes in wind, currents and weather patterns for one to two years
Define/Describe: La Niña
A climate event in the eastern Pacific Ocean in which surface waters are colder than normal
Define/Describe: The Coreolis Effect (What direction does it cause currents to curve in each hemisphere?)
The effect of earth’s rotation on the direction of winds and currents; causes currents NORTH of the equator to move in CLOCKWISE direction and currents SOUTH of the equator to move COUNTER-CLOCKWISE
Define/Describe: Gyre
A group of currents that come together to form a circular rotating current; large system of rotating ocean currents caused by the Coreolis Effect
Define/Describe: Tide
The regular rise and fall of the sea due to the moon’s gravitational pull on Earth
Identify 3 factors that determine the size of a wave
The strength of the wind
The length of time the wind blows
The distance the wind travels
How to calculate tidal range?
Subtract the daily highest tide with the daily lowest tide
Spring Tide
Tides with the greatest difference between consecutive low and high tides
Occurs during a full or new moon when the earth, sun and moon are aligned.
Causes highest high tides and lowest low tides.
This happens because the sun and moon are pulling the water in the same direction. Spring = Straight
Neap Tide
Tides with the least difference between consecutive low and high tides
Occurs during a quarter or three-quarter moon when the earth, sun and moon form a right angle
High tides are not very high and low tides are not very low.
This happens because the sun and moon are pulling earth’s water in two different directions. Neap = Ninety
Describe Overwash
Waves exceed/go over the elevation of the dune; sand is transported across the land and often results in significant damage to coastal property
Explain why there is less vegetation on a primary dune compared to a secondary dune
Wind eroding the dune
Storm surges killing plant life
Salt spray killing the plants
Pro/Con of Jetties & Groins
Pro: Reduce erosion
Con: Causes erosion of one side of the jetty
Pro/Con of Wooden Fencing
Pro: Trap sand and inexpensive
Con: Not strong
Pro/Con of Plastic Fencing
Pro: Trap sand
Con: Plastic could go into the ocean
Pro/Con of Sea Walls
Pro: Strong, protects tidal waves
Con: Expensive, needs repair
Pro/Con of Dredging
Pro: Fastest replenishment
Con: Very expensive
Wetlands
A land area that is covered with a shallow layer of water, freshwater and coastal (salt water)
Benefit of Wetland
Protective haven for developing young
Habitats with food and shelter
Resting areas for migrating birds
Describe brackish water
Water with a level of salinity between freshwater and seawater.
Example: where a river meets a bay
Explain how salinity affects animals in estuaries
Changes in salinity are a problem for animals living in estuaries because the water can have high salinity at times and low salinity at times
What is a nurdle?
Broken down pieces of plastic
What impact do nurdles have on the environment?
Plastics are the number one pollution source floating in the world’s oceans and pass through the food web and harm all animals in the web
Describe why we have not been able to get rid of Garbage Island
It is too large
Pieces have photodegraded into small parts
Plastics will still exist whether in water or not
What can we do to try to stop Garbage Island from getting larger?
We can REDUCE the amount of plastics used.
Something that is more dense than water will ____
sink
Something that is less dense than water will ____
float
Currents on top of the water are called ________, moved by ____
surface currents; winds
Currents below the water are called ________, moved by ____
deep currents; density
