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GEO LECTURE > currents > Flashcards

currents Flashcards

1
Q

what are surface currents?

A

masses of water that flow from 1 place to another

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2
Q

what force drives surface currents?

A

friction from the energy of wind passed to surface waters

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3
Q

explain the movement of air to create wind belts

what is the zone called

A
  1. warm air f/ equator rises northwards
  2. at 30 degrees N/S, air cools and sinks to equator

intertropical convergence zone/doldrums

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4
Q

What causes the surface layer to move?

A

drag of winds

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5
Q

Name some wind belts in the Atlantic

what are they influenced by

A

Westerlies
tradewinds

position of continents

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6
Q

What are gyres?

A

large loops of water in ocean basin (circles)

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7
Q

how many main gyres are there?
name them

A

n pacific
s pacific
n atlantic
s atlantic
indian ocean

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8
Q

What is the latitude of the centers of ALL gyres?

what do you call this region

A

30 degrees s/n

subtropical

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9
Q

how many main currents does each gyre have?

A

4

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10
Q

the coriolis effect explains…

A

how currents are deflected

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11
Q

which way are currents deflected in the N.Hemi and what direction do gyres move there?

A

to the right
clockwise

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12
Q

which way are currents deflected in the s.hemi and which way to gyres move there?

A

left
counterclockwise

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13
Q

how many years does it take for an object to make a trip aroun the N.Atlantic Gyre? N. Pacific?

what sea is in the N.Atlantic? what is it known for

A

3yrs
6yrs

sargasso. calm waters/seaweed

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14
Q

What is the only current that encircles Earth?

A

West Wind Drift

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15
Q

why does the west wind drift go around the earth completely

whaat wind belt is moving it?

where does it split off

A

travels through Antarctica, which lacks landmasses

westerlies

s ocean basins

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16
Q

what does the movement of surface water match up with?

A

global pattern of prevailing winds

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17
Q

what is the indian ocean influenced by?

definiton

A

monsoons

seasonal wind shifts

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18
Q

a change in wind direction leads to a change in

A

surface current direction

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19
Q

describe the transfer of solar radiation from low latitudes

A

get more solar radiation than they release

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20
Q

what are the agents of heat transferr

what percentage does each agent hold in heat transport

A

winds and ocean currents to balance out deficient and excess areas

winds: 3/4; ocean currents: 1/4

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21
Q

When do warm currents exert greatest influence

A

winter

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22
Q

what is the extension of the gulf streamm called

A

north atlantic drift

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23
Q

is the gulf stream warm or cold

A

warm

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24
Q

when is the influence of cold ccurrents most pronouced?
Coast vs inland

A

topics/summer months at mid latitudes

Coast: feel cold current lower temps in summer but very hot on east coast

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25
Q

how do currents flow?

what is the temperature of these currents

A

from low latitudes to high latitudes
hot to cool

warm

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26
Q

how many miles does the gulf stream move?

A

25-75 miles per day

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27
Q

where is aridity intensified?

A

west coasts of subtropical deserts

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28
Q

why is aridity intensified along the west coasts of subtropical deserts?

A

cold offshore water cools atmosphere, stabilizing it, and preventing precipitation

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29
Q

what is another reason why aridity is intensified along the west coasts of subtropical deserts

A

cold currents=temps near dew point=foggy and humid

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30
Q

what is upwelling

A

rising of cold, deep water to warm, surface water

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31
Q

what is coastal upwelling characteristic of?

A

west coasts of continets

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32
Q

how do the winds blow in accordance to upwelling

A

toward equator and parallel to shore

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33
Q

how do the winds and the coriolis effect affect surface water

A

surface water moves away from the shore which allows it to be replaced by cold water

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34
Q

Nutrients and upwelling

A

nutrient concentration increases = more plankton=high productivity

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35
Q

weather of SF in summer

A

foggy bc of upwelling

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36
Q

deep ocean circulation is a response to ___

what are the factors creating this

A

density differences

salinity (high salinity=more dense) and temp (low temp=more dense)

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37
Q

deep ocean circulation aka

A

thermohaline circulation

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38
Q

in high latitudes/polar regions, what is the main leading factor for density? why??

A

salinity bc there is an isothermocline

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39
Q

how are deep ocean currents produced

A

sea ice forms
increases salinity of surface water=denser
sinks

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40
Q

Most water involved in deep-ocean currents begins

so what ocean/continent

A

high lat

antartica and artic poles’ water sinks and goes through the process

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41
Q

what happens once the water sinks?

why

A

temp and salinity stay the same bc not affected by phys porcesses at surface (think of vertical line in deep water zone)

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42
Q

where is the edensest water in the world

A

antarctica

43
Q

describe the movement of deep ocean circulation

A

sluggish
Atlantic–> Indian–> Pacific–> back again

44
Q

when it comess back around, where does it return to and what is the temp of that water

A

comes back to high lats/poleward as warm currents

45
Q

half of the world lives __ miles from the coast

A

60

46
Q

what are waves

A

evidence of energy traveling through water imparted by wind

47
Q

what interface do ocean waves pass through?

A

interface of hydrosphere and atmosphere

48
Q

waves Derive their energy and motion from

A

wind

49
Q

what direction do waves move in?

A

direction of wind

50
Q

crest

A

top of wave

51
Q

trough

A

bottom of wave
separate waves

52
Q

what is btw wave and crests

A

water level where water would be w/no waves

53
Q

wave height

A

distance from crest to trough

54
Q

wave length

A

distance from crest to crest of anotther wave/distance from one trought to another

55
Q

wave period

A

time it takes for a crest to pass a specific point

56
Q

what does the wave length, wave height, and wave period depend on

A
  • fetch
  • time the wind has blown
  • wind speed
57
Q

fetch

A

Distance wind traveled across open ocean

58
Q

what happens when the energy imparted increases?

A

wave height and distance increases

59
Q

how are white caps formed?

A

waves topple over

60
Q

for a particular wind speed, there is a maximum…

what does this mean in terms of the size of the wave

A

fetch and duration

will be fully developed (won’t increase size)

61
Q

what happens when wind stops, moves direction, ir waves leave storm area

A

the waves don’t move in relation to local wiwnds and form swells

62
Q

Does water move across ocean basins?

A

no the waveform moves foward (shape of wave)

63
Q

how does water move?

what does this mean about the moevement of water

A

in a circular oribital motion

returns to same place it started

64
Q

waves move up and down, as well as

A

forward and backward

65
Q

in deep waters, the water is ____ because there is more than a depth of ___

A

neglibible
1/2 wavelength

66
Q

what is the depth of half a wavelength aka

A

wave base

67
Q

as depth increases, the circles get

A

smaller

68
Q

what happens when a wave reaches shore

describe the depth, CIRCLES

A

feel bttom
depth equAL/Less than 1/2 wavelength

ELLIPTICAL

69
Q

describe the speed and wavelength and waves as they approach shore

A

slow down
wavelengths decrease
wave pile up and increase in height
breaks at surf zone

70
Q

surf

A

turbulent water from breakers

71
Q

swash

A

turbulent water moves up shore

72
Q

backwash

A

turbulent water moves down slope

73
Q

what are beaches

A

accumulations of sediment along land margins of lake or ocean

74
Q

where are the sediments of beaches from?

A

whatever is locally abundant (ex. florida: no mts=shells)

75
Q

what are beach grains mostly dominated by

A

quaartz grain

76
Q

do materials remain at beaches? what are beache sthen?

A

no
in transit

77
Q

what is perpendicular sand movement

A

swash and backwash bring sand toward and away from shoreline

78
Q

low wave activity

season

A

more swash than backwash

summer

79
Q

high energy wave activity

season

A

more backwash than swash so the beach erodes

winter (storms frewuent and powerful)

80
Q

wave refraction

A

bending of waves

81
Q

do most waves move toward shore straight on?

A

no, at angle

82
Q

process of wave refrraction

A
  1. waves reach shallow water offshore from a headland
  2. waves slow down while the rest of the wave in deeper water races on ahead
  3. deeper water wave ends up closer to shoreline and is parallel to it despite its dif orientation from og orientation
83
Q

wave attack in headlands

bentness energy
attack

A

headlands: waves reach shallow wsooner rso they’re bent more nearly parallel to headland and attack from all sides (erosion-mroe energy)

84
Q

wave ttack in bays

A

refraction causes wave divergence
less energy=deposition and accumulation of seidments=beach

85
Q

describe longshore currentv

A

swash is at an angle
back wash is streight down the slope of the beach

86
Q

what is the pattern of transportation for longshore transport

A

beach drift (zigzag)

87
Q

what are rlonghsore currents

A

waves that move toward the shore at an angle and produce currents that are parralel to shore

88
Q

what moves more sediment: longgshore currents or beach drift

why

A

longshore currents

water un surf zone is more turbulent sso cna move fine and coarse grains

89
Q

do longshore currents change direction? why?

A

yes, waves approach beach in differnt diferections in dif seasons

90
Q

Wave cut cliffs

A

cutting of land by surf action

91
Q

wave cut platforms

A

benchlike surfaces from receding cliff as rocks fall into sirf and carried out to sea

92
Q

wave cut terrace

A

flat uplifted wave cut platform w/ slopes

93
Q

what are the things that will form from the erosional work of refraction

A

sea caves, sea arches

94
Q

what are sea arches

A

2 sea caves unites/headland cut by erosion

95
Q

seastack

A

isolated rock formation like tiny island
archh fell in

96
Q

what do longhshore currents produce

A

beaches, spit, baymouth bars

97
Q

spit

A

elongated extension of sand from land to bay that hooks landward from thge direction of longhsore current

98
Q

baymouth bar

A

sandbar cuts off bay from ocean

99
Q

name the erosional feeatures

A

wave cut cliff, marine terrace, eave cut platform, sea arch, sea stack

100
Q

tombolo

A

sand conencting mainland to the sea stack or island

101
Q

barrier islands

how do they form

A

low ridges of sand parallel to shore

spits disconnected from mainland, sea level rise, turbulent wter sand up

102
Q

delta

A

accumulation of sediment deposited where stream enters

103
Q

estuary

A

river valley flooded from sea level rise or sibsidence of land,

104
Q

depositional features

A

sit, baymouth bar, tombolo, barrier islands,

GEO LECTURE (19 decks)

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