Lecture 16: Oceans 2 Flashcards
Why do Waves occur?
Due to the effects of wind acting on the surface of the ocean
What is the movement of waves?
Looping orbitals in which motion decreases downward to the wave base
How does Shallow water effect waves?
Wave orbitals flatten in shallow water because of drag
What is Wave Refraction?
When waves become more parallel to seafloor contours (and the shore) as the wave encountours the sea floor
What is Longshore drift?
When waves approach the shore obliquely and undergo refraction and the oscillating motion of water is converted to a longshore current
What is Longshore Drift?
When sediments are carried along the shore during longshore drift? lol
What are Tides?
Rise and fall of the level of the ocean at coastlines twice per day due to gravitation interactions between the earth with the moon and sun
Which body is more important to do with tides?
The moon
Which two bodies have a common center of gravity and where is it located?
The earth and the moon and it is in the earth because the earth has more mass
Why is water pulled toward the moon?
Because the moon’s gravity on the earth’s side is stronger than necessary to maintain orbit. This is why water on the far side pulls away from the moon
What shape is the Hydrosphere pulled into?
An ellipsoid shape
How often do High tides occur?
Twice every 24 hours and 50 minutes
How is tide perceived in shallow water?
Tide is amplified so it is more dramatic than in the ocean
What are Spring tides?
When the sun and moon are in line with the earth and create the seasonally extreme tides: The highest high tides and the lowest low tides
What are Neap Tides?
When the sun and moon are at 90º to each other with respect to the earth and the gravitational effects of the sun and the moon partially cancel out and the tides that occur are the mildest of the year
What are Eustatic changes?
Changes that result from a combination of worldwide sea-level change
What do Eustatic changes result from?
Changes in climate
How is Ice related to Eustatic sea changes?
During climate change ice forms and reduces the level of water reducing global sea levels
How do Tectonic plates affect Eustatic change?
They change the ocean basins which directly impact sea level
What can cause local changes to sea level?
- Tectonic plate movements
- Isostatic responses to ice sheets and ice caps
- Compaction of sediments
What is Isostatic depression and post-glacial rebound?
When ice melts or glaciers move causing regional differences in tide due to the rebounding of the mantle
Where can Ocean sediments be deposited?
In oceans near to the coast, on the continental shelf, or in the deep ocean
In what way can ocean sediments be deposited on the coast?
Via deltas, estuaries and beaches
What are deep ocean sediments known as?
Pelagic sediments
