Final Flashcards
What percentage of ocean water volume is affected by surface circulation?
10%
The remaining 90% is too deep to be affected by wind.
What drives deep-water circulation in the ocean?
Density differences due to temperature and salinity
This is known as Thermohaline Circulation.
What is Thermohaline Circulation?
Deep-water circulation driven by temperature and salinity differences
It involves heavier water sinking and lighter water rising.
How long can a parcel of water keep its temperature and salinity characteristics after sinking?
1000 years or longer
What percentage of ocean water has a narrow range of temperature and salinity characteristics?
75%
This is characterized by 0–5°C and 34–35‰.
What are water masses?
Distinct packages of water with unique temperature and salinity combinations
They are named for their formation location and flow path.
What is the Mediterranean Intermediate Water (MIW)?
A warm and salty water mass formed in the Mediterranean Sea
It flows through the ocean at an intermediate depth.
What are the densest water masses and how are they formed?
Cold and salty water masses formed by freezing winds at high latitudes
What is Antarctic Bottom Water (AABW)?
A dense water mass formed near Antarctica
It sinks into the deepest parts of the ocean.
What role does CO2 content in deep water play in the Carbonate Compensation Depth (CCD)?
It determines how much CaCO3 is preserved as sediments on the ocean floor
What happens to organic carbon in sediments with low O2 content?
It can convert to CH4 (methane gas)
Methane can act as a greenhouse gas if released.
What is the effect of temperature on methane gas in sediments?
Cold temperature keeps methane frozen; warming can release it
How long does it take for a water mass to make a round trip from the surface to the deep ocean and back?
1000–1500 years
What is the significance of the deep ocean’s capacity to absorb heat and greenhouse gases?
It can act as a buffer to absorb excess heat and gases
What are some chemical tracers used to track deep-water motion?
- Carbon-14 (14 C)
- Hydrogen-3 (3 H or tritium)
- Lead
- Chlorinated fluoro-carbons (CFCs)
True or False: Deep-water currents move faster than surface currents.
False
Deep-water currents typically move at about 1 km/day compared to 2–5 knots for surface currents.
Crest of a wave
The peak or highest point of a wave
Trough of a wave
The lowest point of a wave
Wave height
The difference in height between the crest and the trough
Wavelength
The horizontal distance between two consecutive crests or troughs
Wave period
The time interval between two crests (or two troughs) passing a fixed point
Wave speed (celerity)
Calculated by dividing the wavelength by the wave period (meters per second)
Factors affecting wave size
Stronger wind velocity
Types of wind-generated waves
Seas (chaotic waves in a storm)
Constructive interference
When two crests or two troughs coincide
Destructive interference
When a crest coincides with a trough
Wave motion in deep water
Water molecules move in circular orbits and do not interact with the sea bottom
Wave motion in shallow water
Waves slow down
Wave refraction
The bending of waves as they approach shallow water
Tsunami causes
Sudden disturbances like earthquakes
Tsunami speed in deep water
Can travel up to 500 mph (800 km/h)
Storm surge
A mound of water pushed against the shore by a storm
Internal waves
Underwater waves that move along density boundaries (pycnoclines) and travel more slowly than surface waves
What causes most ocean waves?
Wind pushing the water surface into a wave form
Three factors that affect wave size
Wind velocity
What is a tsunami?
A wave caused by sudden seafloor movement due to earthquakes
What happens to tsunamis near shore?
Wave height increases dramatically as water piles up behind the front of the wave
How do tsunamis cause destruction?
Massive flooding and powerful wave energy destroying coastal areas
What is wave interference?
When waves cross and pass each other
What is constructive interference?
When two wave crests or two troughs coincide
What is destructive interference?
When a crest coincides with a trough
How do water molecules move in deep water waves?
Circular motion that does not interact with the sea bottom
How do water molecules move in shallow water waves?
Elliptical motion as waves interact with the sea bottom
What causes breaking waves?
Bottom friction slows waves down
What is wave refraction?
The bending of waves as they approach a shoreline due to differences in speed
How does wave refraction affect coastlines?
Waves focus energy on headlands (erosion) and spread out in bays (deposition)
What is storm surge?
A large mound of water pushed onshore by strong storms
What causes storm surge?
Low atmospheric pressure and strong winds driving water inland
What is an internal wave?
An underwater wave that moves along density boundaries (pycnoclines) with large heights and slow speeds
Why are tsunami warning systems important?
They help detect potential tsunamis and warn coastal populations to evacuate
How can people recognize an incoming tsunami?
Rapid withdrawal of water from the shore or strong earthquake near the coast
Why did the 2004 Indian Ocean tsunami cause so many deaths?
Lack of education and warning systems led people to walk onto the exposed seafloor before larger waves arrived
How fast do tsunami waves travel in the deep ocean?
Up to 500 mph (800 km/h)
What happens to a tsunami’s wavelength and height near shore?
Wavelength shortens and height increases dramatically
What determines how a wave breaks?
The slope of the seafloor; gentle slopes cause spilling breakers
