Ch 6b: Hydrosphere (Oceans) Flashcards

1
Q

Oceans cover:

A

71% of Earth’s surface, uneven distribution.

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2
Q

Max depth of the ocean, average depth, volume of water

A

11km, 4.5km, 1.35x10^18

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3
Q

Ocean structure

A

Changing layers: fresh water influx, ocean size, more land exposure. Temperature, salinity, density

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4
Q

Ocean layer changes are more

A

noticeable at the surface and near coastlines.

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5
Q

Ocean water properties: Density

A

Variable and Temperature dependent, pycnocline.

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6
Q

Ocean water properties: Salinity

A

varies from 32-37%. Increases with depth, salinity is high where evaporation is high. Low where river water enters ocean

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7
Q

Temperature and Salinity with Depth

A

saline water is denser sinks

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8
Q

Halocline:

A

is region of rapid salinity change

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9
Q

Thermocline:

A

is zone of rapid temperature change

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10
Q

Ocean Temperature:

A

surface varies from 0 to 28degrees, still remains above 0 at depth. Lowest is 0.4 as salt doesn’t allow the water to freeze.

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11
Q

Ocean composition

A

relatively constant, proportions do not change but the amounts can change. Species maintain

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12
Q

Ocean movement: surface currents

A

Wind driven surface currents, 10% by volume. Caused by atmospheric circulation and Earth’s rotation. Affects upper 100m

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13
Q

Large scale movement: subsurface

A

Density driven subsurface currents, 90% by volume. Drives the thermohaline circulation

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14
Q

ENSO

A

El Nino -southern oscillation, occurs in the pacific ocean. Extreme ends are termed El Nino and La Nina

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15
Q

La Nina

A

lower pacific ocean temperature than normal

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16
Q

El Nino

A

higher pacific ocean temperature than normal

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17
Q

Coriolis Effect

A

Objects moving in a straight line appear to curve relative to observer on solid Earth

18
Q

Coriolis Effect: Rotates about its vertical axis

A

CCW in Northern Hemisphere,

CW in Southern Hemisphere

19
Q

Ekman Effect

A

Coriolis deflects wind driven currents in Northern hemisphere. Slightly CW of actual wind direction, deeper currents are progressively rotated CW. Overall average water movement is 90degrees CW of wind

20
Q

Ekman Transport: Upwelling occurs…

A

where Ekman Transport is offshore

21
Q

Ekman Transport: Downwelling occurs…

A

where Ekman transport is onshore

22
Q

Geological Aspects

A

dominated by plate tectonics, sedimentation

23
Q

Continental Margins

A

Type depends greatly on plate tectonic activity, type determines coastal shape and properties.

24
Q

Continental Margins: Active Margin

A

occur along subduction zones or transform faults. Volcanically and tectonically active regions. Sediments of variable thickness. (terrigeneous, carbonates, volcanics)

25
Q

Continental Margins: Passive Margin

A

Occur far from plate boundaries, flat lying, gentler gradients. Abundant shallow water sediments. (terrigeneous, carbonates)

26
Q

Coastlines Modified by:

A

waves, tides, mass wasting events, uplift.

27
Q

Coastlines are regions of

A

erosion and deposition

28
Q

Waves created …

A

primarily by the friction between water and wind.

29
Q

Larger waves are created by:

A

earthquakes, landslides, volcanic eruptions, extraterrestrial impacts

30
Q

Wave depth is about

A

1.2 the wavelength

31
Q

In deep water, the wave speed is

A

V = L/T

32
Q

Wave strikes the beach at an angle, explain

A

Part of the wave nearest the shore hits the shallow water first and slows down, creates a bend in the wave and rest of the wave follows the bend

33
Q

Longshore Transport is

A

a shallow water current, moves parallel to the shoreline. Caused by wave refraction. Controls depositional shoreline features and erosion and transport of sediment.

34
Q

Tides are due to

A

gravitational pull of the sun and the moon.

35
Q

Types of Tides:

A

Spring and Neap

36
Q

Tides: Neap

A

low difference between low and high tides

37
Q

Tides: Spring

A

big difference between low and high tides

38
Q

Beaches are

A

gently sloping surfaces, washed over by waves, covered with sediment, deposition or erosion dominated, short-term and unstable features

39
Q

Sea Level Changes are usually

A

local to regional in effect: tectonic uplife or subsidence, isostatic rebound, global warming, human causes

40
Q

Sea Level ups and downs

A

Glaciation promotes drops and global warming promotes rises.