Oceanography FlashcardsDefine the following terms: wave height, wavelength, wave speed, and wave steepness.

Define the following terms: wave height, wavelength, wave speed, and wave steepness.

Wave Height: vertical distance the crest of a wave and the trough. It is a measure of the wave’s size.

Wavelength: horizontal distance between 2 consecutive crests or 2 consecutive troughts of a wave. It represents the length of one complete wave cycle.

Wave Speed: the rate at which a wave travels through a medium, calculated as the distance the wave propagates per unit of time.

Wave Steepness: the ratio of wave height to wavelength

The R/V Spartina is cruising off the Georgia coast taking water and sediment samples when she encounters a storm. The ship's captain asks you to assist him by calculating the frequency of the waves and the wavelength. The wave speed is measured at 4 meters per minute. The wave period is determined to be 12 seconds. What is the wavelength and frequency of the storm swells encountered by the R/V Spartina?

frequency = 1/T.

T = 12 seconds.

frequency = 1/12 or 0.0833 Hz

Wavelength: λ = v/f

v = 4m/min/60

λ = 0.0667/0.0833

wavelength = 0.8m

Based on the graph below, what is the approximate speed, in meters per second, of a deep-water wave with a wavelength of 200 meters?

1. Locate wavelength 200m on the graph on the x-axis

2. Move up vertically from 200 meters until you intersect with the curve with the graph

3. From the intersection point, move horizontally to the y-axis to read the corresponding speed.

At 200 meters wavelength, the speed is approximately 15 meters per second.

Waves from separate sea areas move away as swell and produce an interference pattern when they come together. If Sea A has wave heights of 1.5 meters and Sea B has wave heights of 3.5 meters, what would be the height of waves resulting from constructive interference?

In constructive interference, the wave heights add together.

Resulting wave height = wave height of sea a + wave height of sea b.

Wave height of sea a = 1.5m

Wave height of sea b = 3.5m

Resulting wave height = 1.5 + 3.5 = 5.0 meters.

Answer: 5.0 meters

Describe what happens to a deep-water wave when it enters shallow water and eventually breaks.

As a deep water wave enters shallow water, it slows down, its wavelength shortens, its height steepness increase, and it eventually breaks when it becomes too steep to remain stable.

Briefly describe how tsunami are generated and include a description of characteristics such as wavelength and wave speed. Do tsunami behave as shallow-water waves? Why
or why not and how does this influence their movement in shallow versus deeper water? What would the shoreline look like when the trough of tsunami arrives?

Tsunamis are generated by large-scale disturbances, such as undersea earthquakes, volcanic eruptions, meteor impacts, or landslides, that displace large volumes of water.

Tsunamis behave as shallow-water waves because their wavelengths are much greater than the ocean depth, causing their speed to depend on water depth.

When the trough of a tsunami arrives at the shoreline, it can draw water away from the coast, exposing the seabed, a phenomenon often describe as a sudden and dangerous “withdrawal” of the ocean.

Briefly describe why the Sun's influence on Earth's tides is only 46% that of the Moon, even though the Sun is much more massive that the Moon.

Tidal forces depend the relative difference in gravitation pull across Earth’s diameter, which is determined by the object’s proximity rather than it’s mass alone. Although the Sun is much more massive, it is also about 400 times farther away from Earth than the Moon, so the difference in its gravitational pull across Earth’s surface is much smaller, resulting in a weaker tidal effect.

How many spring tides occur in the time it takes the Moon to make one complete orbit around Earth? Describe what the Moon looks like from Earth during each occurrence.

2 spring tides occur. It occurs during the new moon and full moon.

Distinguish between spring tides and neap tides.

Spring Tides:

• occurs during new moon and full moon phases

• creating the highest high tides and lowest low tides

Neap Tides:

• occurs during the first quarter and third quarter moon phases

• resulting in lower high tides and higher low tides

What is longshore drift and how is it related to a longshore current?

Longshore drift is the process by which sand and sediment are transported along a shoreline by the action of waves and currents.

A longshore current us a water current that flows parallel to the shoreline, created by the same wave that cause longshore drift.

Describe the response of a barrier island to a rise in sea level. Why do some barrier islands develop peat deposits running through them from the ocean beach to the salt marsh?

A barrier island typically responds by migrating landward and upward through processes like over wash and long shore drifts.

Peat deposits form in barrier islands due to the accumulation of organic material in low-energy, waterlogged environments like salt marshes. As the island shifts landward, sand from overwash buries these deposits, creating a record of past marsh locations.

Distinguish between an emerging shoreline and a submerging shoreline.

Emerging shoreline: one where the land is rising relative to sea level, often due to tectonic uplift or a decrease in sea level

Submerging shoreline, the land is sinking relative to sea level, or when sea level rises. This leads to the flooding of coastal areas, with features like beaches and coastal plains becoming submerged.

Describe the types of hard stabilization and what each is intended to do. Include in your answer the drawbacks of each method, as well as some of the alternatives to hard stabilization.

Seawalls:

• Purpose: built along shorelines to protect coastal areas from the force of waves and to prevent erosion.

• Drawbacks: expensive to construct and maintain.

• Alternatives: living shorelines such as plants or natural materials

Groins

• Purpose: structures built perpendicular to the shoreline to trap sand moving along the coast due to longshore drift.

• Drawbacks: Groins can starve downcurrent beaches of sand, leading to increased erosion downstream.

• Alternatives: Beach nourishment

Breakwaters

• Purpose: offshore structures that reduce the forces of waves before they reach the shore, providing calm water for harbors or protecting the shoreline from direct wave attack.

• Drawbacks: disrupt natural coastal processes and sediment transport, leading to erosion in areas down current.

• Alternatives: Artificial reefs or living shorelines

Jetties

• Purpose: structures built at the entrances to harbors or rivers to prevent sediment buildup and to stabilize channels for navigation.

• Drawbacks: sediment starvation down the coast, leading to erosion in other areas.

• Alternatives: sediment bypassing

Distinguish between estuaries, lagoons, and marginal seas and give an example of each.

Lagoons: shallow bodies of water separated from the open sea by a barrier. One example is the Great Barrier Reef Lagoon.

Estuaries: coastal areas where freshwater from river or streams meets and mixes with saltwater from the ocean. One example is the Chesapeake Bay.

Marginal Seas: are large relatively shallow seas that are partially enclosed by land, but still open to the ocean. One example is the Mediterranean Sea.

List and briefly describe the four types of estuaries based upon origin and give an example of each.

Coastal Plate Estuaries: rising sea levels submerge a river valley, creating.a broad, shallow area where freshwater from the river mixes with seawater. One example is Chesapeake Bay.

Bar-Built Estuaries: sandbars or barrier islands are built up by wave action and currents, partially enclosing a body of water from the ocean. One example is Laguna Madre.

Tectonic Estuaries: land subsides due to tectonic activity, creating a depression that is later filled with seawater. One example is San Francisco Bay.

Fjord Estuaries: deep, steep-sided valleys that are carved by glaciers and later flooded by rising sea levels. One example is the Norwegian Fjords.

Why do many marine pollution experts consider oil to be among the least damaging pollutants introduced into the ocean?

• Biodegradation: Microorganisms in the ocean can break down oil into less harmful substances over weeks to months, depending on the type of oil and environmental conditions.

• Physical Dispersion: Waves, wind, and currents help to disperse the oil, reducing its concentration in any one area and spreading it out across the ocean.

• Evaporation: Lighter oils can evaporate into the atmosphere, reducing their impact on marine ecosystems.

• Oil Sinks to the Bottom or Forms Tar Balls: Some heavier oils can sink to the ocean floor or form tar balls, where they may pose less of a threat to marine life than floating oil slicks.

Oil decomposes a lot faster than other pollutants. Such as biodegradtion, physical dispersion such as waves, wind, or currents dispersing the oil, evaporation, and oil sinking to the bottom.

What properties have contributed to plastics being considered a miracle substance? How do those same properties cause plastics to be unusually persistent and damaging in the marine environment?

• Durability: Plastics are strong, resistant to wear and tear, and can withstand harsh environmental conditions, making them ideal for many applications.

• Lightweight: Plastics are lighter than many other materials, making them easy to handle, transport, and use in a wide range of products.

• Water Resistance: Plastics are non-porous and resistant to water, which makes them ideal for products that need to remain unaffected by moisture.

• Low Cost: Plastics are relatively cheap to produce, making them accessible for widespread use.

• Mold ability: Plastics can be molded into virtually any shape, enabling the creation of a vast range of products, from packaging to medical devices.

However, these very properties that make plastics so beneficial also contribute to their persistence and damaging effects in the marine environment:

1. Durability and Resistance to Degradation: Plastics do not biodegrade easily. They can persist in the ocean for hundreds of years, leading to long-term pollution that accumulates over time.

2. Ingestion by Marine Life: The lightweight nature of plastics allows them to float in the ocean, making them accessible to marine animals. Many species mistake plastic debris for food, which can lead to ingestion, malnutrition, or even death.

3. Fragmentation into Microplastics: Over time, plastics break into smaller pieces (microplastics), which can be ingested by marine organisms at nearly all levels of the food chain. These microplastics are difficult to remove and can accumulate in the food web.

4. Chemical Leaching: Plastics can leach harmful chemicals into the water over time, further polluting the environment and potentially causing toxic effects on marine life.

Distinguish between plankton, nekton, and benthos and give an example of each.

Plankton: drift with the current. Ex. Diatoms, copepods

Nekton: actively swim against currents. Ex. Tuna, dolphins

Benthos: Live on or near the seafloor Ex. Crabs, sea stars

How do you define a living organism?

A living organism is defined as a being that exhibits all of the following characteristics: movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition. Mrs. Gren

Compare and contrast warm and cold-water marine species in terms of life span, body size, and relative abundance.

Warm-water species: shorter lifespan, smaller size, higher abundance/a lot

Cold-water species: longer lifespan, larger size, lower abundance

Give an example of (a) a positive feedback loop and (b) a negative feedback loop.

Positive Feedback Loop: Ice-Albedo Feedback

Negative Feedback Loop: Thermoregulation in Humans

List and define the five components of Earth's climate system.

• Atmosphere: The layer of gases surrounding Earth,

• Biosphere: All living organisms on Earth, including plants, animals, and microorganisms.

• Cryosphere: The frozen water component of Earth, including glaciers, ice caps, sea ice, and permafrost.

• Hydrosphere: The Earth's water in all forms, including oceans, rivers, lakes, and groundwater, as well as water vapor in the atmosphere.

• Lithosphere: The Earth's solid outer layer, including the crust and upper mantle.

What are proxy data?

Indirect evidence or measurements used to infer past climate conditions, especially when direct observations (like temperature records) are not available.

Give two examples for commonly used proxy data and describe their relationship to their respective environmental conditions.

Tree Rings

• Proxy: Tree rings are formed as trees grow, with one new ring being added each year.

• Relationship to Environmental Conditions: The width of tree rings is generally related to the amount of rainfall and temperature during the growing season.

Ice Cores

• Proxy: Ice cores are cylinders of ice drilled from glaciers or ice sheets, which contain layers that have accumulated over time.

• Relationship to Environmental Conditions: The composition of the air bubbles in the ice cores, such as the concentration of greenhouse gases (CO₂ and methane), reflects past atmospheric conditions.