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geog 272 > chapter 6 > Flashcards

chapter 6 Flashcards

1
Q

@ what is driving all of the wind and oceans movement

A

the sun

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2
Q

Ocean currents

A

redistribute more heat in a zone straddling the equator between the 17th parallels in each hemisphere

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3
Q

how is the Earth’s atmospheric circulation caused

A

imbalance between equatorial energy surpluses and polar energy deficits

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4
Q

what does Earth’s atmospheric circulation do

A

transfers both energy and mass on grand scale, determine Earth’s weather patterns and the flow of ocean current, dominant medium for redistributing energy from about 35degree latitude to the poles in each hemisphere, also spreads air pollutants, natural or human-caused, worldwide

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5
Q

Air pressure

A

pressure produced by motion, size, and number of gas molecules in the air and exerted on surfaces in contact with the air
Warm, humid air is associated with low pressure and cold, dry air is associated with high pressure, b/c ↓
With increased activity, the spacing between molecules increases so that density is reduced and air pressure decrease

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6
Q

why is moist air is lighter

A

because the molecular weight of water is less than that of the molecules making up dry air

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7
Q

@ instruments for measuring air pressure

A

mercury barometer (column of mercury in a tube, one end open, one end sealed) and aneroid barometer (partially evacuated, sealed cell)

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8
Q

Wind

A

the horizontal movement of air relative to Earth’s surface; produced essentially by air pressure differences from place to place; turbulence, wind updrafts and downdrafts, adds a vertical component; its direction is influenced by the Coriolis force and surface friction

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9
Q

@ instrument for measuring wind direction

A

an anemometer measures wind speed and a wind vane determines wind direction; the standard measurement is taken 10m above the ground to reduce the effects of local topography on wind direction

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10
Q

Four forces determine both speed and direction of winds

A

gravitational force, pressure gradient force, Coriolis force, and friction force

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11
Q

Gravitational force

A

exerts a virtually uniform pressure on the atmosphere over all of Earth. Gravity compresses the atmosphere, with the density decreasing as altitude increases. The gravitational force counteracts the outward centrifugal force acting on Earth’s spinning surface and atmosphere

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12
Q

Pressure gradient force

A

drives air from areas of higher barometric pressure (more-dense air) to areas of lower barometric pressure (less-dense air), thereby causing winds.

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13
Q

Isobar

A

an isoline connecting all points of equal atmospheric pressure, provides a portrait of the pressure gradient between an area of higher pressure and one of lower pressure, by the spacing between isobars, the steeper the faster

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14
Q

Coriolis Force

A
  • a deflective force that make wind travelling in a straight path appear to be deflected in relation to Earth’s rotating surface
  • a plane experience an overall movement away from Earth’s axis, the pilot have to corrects for this defective force
  • The Coriolis force just balances the pressure gradient force, the winds between higher-pressure and lower-pressure areas in the upper troposphere flow parallel to the isobars, along lines of equal pressure
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15
Q

Contribution to Coriolis force

A

the speed of Earth’s rotation which varies with latitude (no deflection at the equator, and increase with latitude, to reach the max deflection at the poles), the direction in which the object is moving, and the speed of the moving object (the faster, the greater its apparent deflection)

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16
Q

Friction Force

A

drags on the wind as it moves across Earth’s surfaces but deceases with height above the surface
- at the surface, the effect of friction varies with surface texture, wind speed, time of day and year, and atmospheric conditions, rougher surfaces produce more friction, friction decreases wind speed

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17
Q

Geostrophic wind

A

a wind moving between areas of different pressure along a path that is parallel to the isobars. It is a product of the pressure gradient force and the Coriolis force
- Near the surface, friction prevents the equilibrium between the pressure gradient and Coriolis forces that results in geostrophic wind flows in the upper atmosphere
- Not at the surface

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18
Q

Surface winds

A

pressure Gradient force + Coriolis Force + Friction Force, surface wind at the surface of the earth/ at lower troposphere

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19
Q

Anticyclone

A

high pressure center
- In Northern Hemisphere; anticyclone rotate clockwise
- In Southern Hemisphere; anticyclone rotate counterclockwise

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20
Q

Cyclone

A

low pressure center
- In Northern Hemisphere; cyclone rotate counterclockwise
- In Southern Hemisphere; cyclone rotate clockwise

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21
Q

Primary circulation

A

consisting of general worldwide circulation

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22
Q

Secondary circulation

A

consisting of migratory high-pressure and low-pressure systems

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23
Q

Tertiary circulation

A

including local winds and temporal weather patterns

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24
Q

Meridional flows

A

winds that move principally north or south along meridians of longitude

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25
Q

Zonal flows

A

winds moving east or west along parallels of latitude

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26
Q

what is the driving force for ocean surface currents

A

The frictional drag

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27
Q

Equatorial low or equatorial trough

A

a thermally caused low-pressure area that almost girdles (encircle) Earth, with air converging and ascending all along its extent; also called the intertropical convergence zone (ITCZ), cause; thermal, air temperature/moisture; warm/wet, heavy rainfall, trade winds

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28
Q

Polar highs

A

Weak, anticyclonic, thermally produced pressure systems positioned roughly over each pole, cause; thermal, air temperature/moisture; cold/dry

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29
Q

Subtropical highs

A

One of several dynamic high-pressure areas covering roughly the region from 20° to 35°N and S latitudes; responsible for the hot, dry areas of Earth’s arid and semiarid deserts, anticyclone, cause; dynamic, air temperature/moisture; hot/dry, westerlies

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30
Q

Subpolar low

A

A region of low pressure centred approximately at 60°C latitude in the North Atlantic near Iceland and in the North Pacific near the Aleutians as well as in the Southern Hemisphere. Airflow is cyclone; it weakens in summer and strengthens in winter, cause; dynamic, air temperature/moisture; cool/wet

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31
Q

why is rainfall heavy in the equator

A

because constant high sun altitude and consistent day-length bring warming affect, which create lighter, less-dense, ascending (leading upward) air, with wind, the converging air is extremely moist and full of latent heat energy, when it rise, expands and cools, it produced condensation

32
Q

Intertropical convergence zone (ITCZ)

A

is identified by bands of clouds along the equator, air converging and sending all along its extent, causing low-pressure area

33
Q

Trade winds

A

winds converging at the equatorial low-pressure through, forming the intertropical convergence zone, most consistent winds on Earth

34
Q

Hadley cells

A

in each hemisphere that begin with winds rising along the ITCZ, air moves northward and southward into the subtropics, descending to the surface and retiring to the ITCZ, Earth’s principal surface winds

35
Q

why in the ITCZ winds are calm or mildly variable

A

because of the weak pressure gradient and the vertical ascent of air, the sunlight beams directly down causes the air to warm and rise straight up rather than blow horizontally, resulting in little or no wind

36
Q

Doldrums

A

the equatorial calms, wind

37
Q

subtropical highs

A

High-pressure zone of hot, dry air brings clear, frequently cloudless skies over the Sahara and Arabian Deserts and portion of the Indian Ocean

38
Q

Westerlies

A

are the dominant winds flowing from the subtropics toward higher latitudes, Earth’s principal surface winds, stronger in winter

38
Q

Aleutian Low

A

The North Pacific subpolar lows

39
Q

Icelandic Low

A

The North Atlantic subpolar lows

40
Q

Polar front

A

area of contrast between cold air from higher latitudes and warm air from lower latitudes

41
Q

why are the high-pressure cells weak in the polar

A

Because polar receive little energy from the Sun to put into motion, when it does form it tends to locate over the colder northern continental areas in winter

42
Q

Polar easterlies

A

variable, weak, cold, and dry winds moving away from the polar region; an anticyclonic circulation

43
Q

Antarctic High

A

A consistent high-pressure region centred over Antarctica; source region for an intense polar air mass that is dry and associated with the lowest temperatures on Earth

44
Q

Constant isobaric surface

A

an elevated surface in the atmosphere on which all points have the same pressure, usually 500 mb. Along this constant-pressure surface, isobars mark the paths of upper-air winds (wider spacing indicates slower winds)

44
Q

Rossby wave

A

an undulating horizontal motion in the upper-air westerly circulation at middle and high latitudes

45
Q

Jet Streams

A

irregular and concentrated band of westerly wind, strong during winter, travelling at 300km x h-1

46
Q

what causes variation in jet-stream speeds

A

The pattern of high-pressure ridges and low-pressure troughs in the meandering jet streams

47
Q

where are the Subtropical jet stream

A

between 20° to 50°N latitude

47
Q

where are the Polar jet stream

A

between 30° to 70°N latitude

48
Q

Monsoon

A

an annual cycle of dryness and wetness, with seasonally shifting winds produced by changing atmospheric pressure systems, means season

49
Q

how are the monsoon in winter

A

dry and cold air flows from north to south

50
Q

how are the monsoon in summer

A

wet and humid air flows from south to north

51
Q

Land and sea breezes

A

wind along coastlines and adjoining interior areas created by different heating characteristics of land and water surfaces - onshore (landward) breeze in the afternoon and offshore (seaward) breeze at night

52
Q

Mountain and valley breezes

A

a light wind produced as cooler mountain air flows downslope at night and as warmer valley air flows upslope during the day

53
Q

Katabatic winds

A

Air drainage from elevated regions, flowing as gravity winds. Layes of air at the surface cool, become denser, and flow downslope; know worldwide by many local names

54
Q

what the force of wind speeds considered suitable for power development

A

6.5 m x s -1

55
Q

Important factors affecting oceanic currents

A

Coriolis force, density differences caused by temperature and salinity, the configuration of the continents and ocean floor, and the astronomical forces that cause tides

56
Q

what is the driving force for ocean surface currents

A

The frictional drag

57
Q

surface currents in the northern hemisphere

A

winds and ocean currents move clockwise

58
Q

surface currents in the southern hemisphere

A

winds and ocean currents move counterclockwise

59
Q

Pacific Gyre

A

transport of marine debris by Pacific Ocean currents

60
Q

Western intensification

A

the piling up of ocean water along the western margin of each ocean basin, to a height of about 15cm; produced by the trade winds that drive the oceans westward in a concentrated channel

61
Q

Upwelling current

A

an area of the sea where cool, deep waters, which are generally nutrient-rich, rise to replace vacating water

62
Q

Downwelling current

A

an area of the sea where a convergence or accumulation of water thrusts excess water downward

63
Q

Thermohaline circulation

A

deep-ocean currents produced by differences in temperature and salinity with depth; Earth’s deep currents, slow and hauls larger volumes of water

64
Q

is it warmer current or colder current that’s on the surface

A

warmer current

65
Q

El Niño-Southern Oscillation (ENSO)

A

sea-surface temperatures increase, sometimes more than 8°C above normal in the central and eastern Pacific, replacing the normally cold, nutrient-rich water along Peru’s coastline. Pressure patterns and surface ocean temperatures shift from their usual locations across the Pacific, forming the Southern Oscillation
- warm phase (when surface waters in the central and eastern Pacific increase to more than 8°C above normal)
- South Africa, Southern India, Australia, and the Philippines; strong hurricanes in the Pacific, heavy precipitation
- hurricanes season weakens

66
Q

El Niña

A

cold phase (when surface waters in the central and eastern Pacific cool to below normal by 0.4°C or more)
- Indonesia, the south Pacific, and northern Brazil; extensive flooding
- hurricane season strengthens

67
Q

Pacific Decadal Oscillation (PDO)

A

A pattern of sea-surface temperatures, air pressure, and winds that shifts between the northern and tropical western Pacific (off the coast of Asia) and the eastern tropical Pacific (along the U.S. West Coast)
- strongest in the North Pacific

68
Q

Negative phase of Pacific Decadal Oscillation (PDO)

A

occurs when higher-than-normal temperatures dominate in the northern and tropical regions of the western Pacific and lower temperatures occur in the eastern tropical region

69
Q

Positive phase of Pacific Decadal Oscillation (PDO)

A

warm phase; when lower-than-normal temperatures were found in the northern and western Pacific and higher-than-normal temperatures dominated the eastern tropical region

70
Q

North Atlantic and Arctic Oscillations (NAO)

A

A north- south fluctuation of atmospheric variability as pressure differences between the Icelandic Low and the Azores High in the Atlantic alternate from a weak to a strong pressure gradient

71
Q

Positive phase of North Atlantic and Arctic Oscillations (NAO)

A

when a strong pressure gradient is formed by a lower-than-normal Icelandic low-pressure system and a higher-than-normal Azores high-pressure cell

72
Q

Negative phase of North Atlantic and Arctic Oscillations (NAO)

A

weaker pressure gradient than normal between the Azores and Iceland and reduced westerlies and jet streams

geog 272 (11 decks)

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