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goph375 > Ch 9 > Flashcards

Ch 9 Flashcards

1
Q

Weather

A

short-term processes

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2
Q

Climate

A

long-term processes

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3
Q

External sources of energy

A

Solar radiation
- ~4000x interior energy
- Some from Earth, moon, and sun tides

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4
Q

Sun’s electromagnetic radiation:

A

Radiowaves through visible, X-rays to gamma rays
- Visible light = 43% of light at the surface

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5
Q

Solar radiation received by Earth

A

Reflected/absorbed varies with latitude (30/70 avg ratio)
Equatorial belt:
- 38N, 38 S
- 2.4x polar region absorption
- net heating
Polar regions:
- net cooling

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6
Q

Heat and energy transfer from

A

equator to poles

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7
Q

Circulation patterns determine weather and climate:

A

Earth’s orbit:
- seasons - variable heating with latitude
Earth’s rotation and gravity:
- Oceanic and atmospheric circulation

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8
Q

The greenhouse effect raises Earth’s surface temp

A

Solar radiation
- short wavelength
- raises Earth’s surface temp
Excess heat re-radiated
- long wavelength (tends to get trapped like short wavelengths)
- absorbed by GHGs
- raises Earth’s surface temp

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9
Q

Albedo

A
  • direct reflection of solar radiation
  • 30% for whole earth
  • ice cover increases albedo (keeps poles cold)
  • liquid water decreases albedo (accelerates melting)
    ice albedo: 70-90%
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10
Q

The hydrologic cycle

A

1) H2O evaporates from oceans and plant transpiration (rises as vapour in atmosphere)
2) vapour condenses (falls as precipitation)
3) gravity returns H2O to oceans (continuously operating, distillation and filter system, ~1/4 solar energy drives water evaporation)

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11
Q

Extraordinary properties of H2O

A

Highest: heat capacity of all solids, heat conduction of all liquids, latent heat of vaporization, dielectric constant of all liquids, surface tension
2nd highest: latent heat of fusion
- Bipolar molecule

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12
Q

Water vapour and humidity

A

By vol, atmosphere is 0-4% H2O vapour
Humidity: amount of H2O vapour in air
Saturation humidity: max vapour content
Relative humidity: ratio of humidity and saturation humidity
- If temp of air is lowered without changing humidity, it will reach 100% relative humidity
- When 100% relative humidity, excess H2O vapour condense to liquid water -> temp = dew point
- Temp “felt” depends on relative humidity -> heat index

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13
Q

Latent heat

A
  • H2O absorbs, stores, and releases energy when changing phases
  • Stored or released energy = latent heat
  • Water to ice: releases heat
  • Ice to water: absorbs heat
  • Evaporating water: heat absorbed
  • Condensing water: heat released
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14
Q

Differential heating of land and water

A

Low heat capacity of rock = heats up and cools down quickly

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15
Q

Winter heating of land and water

A
  • Land cools quickly, cool air sinks toward ground -> high pressure region
  • Oceans retain warmth, warm moist air rises, cools, condenses, rains over oceans
  • Land retains less heat but can return it faster
  • Ocean retains more heat but takes longer to return
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16
Q

Summer heating of land and water

A
  • Land heats up quickly, hot, dry air rises -> low pressure
  • Ocean warms slowly - cool and moist air over ocean
  • Warm land draws cool, moist air from oceans -> warms, rises, cools, condenses, rains over land
  • Land surface heats up faster compared to ocean, so circulation reverses -> precip on land
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17
Q

Atmosphere converts solar energy into wind:

A

Stable avg annual temp at Earth’s surface
- Low density, warm air rises at equator, flows to poles, cools, sink
- Dense, cold polar air flows to equator
- Earth’s rotation adds complexity to flows
Atmospheric circulation moves heat around Earth

18
Q

Layering of lower atmosphere:

A

75% of atmosphere within 10km of surface
Air flows from higher to lower pressure
- P decreases with altitude -> upward flow
- Added heat increases upward flow further up by convection
Atmosphere layered by temp
- Lowest layer: troposphere, 8km @ poles, 18km @ equator
- Warmer to cold with altitude
- Turbulence as warm air rises and cold air sinks

19
Q

Troposphere
Tropopause
Stratosphere
Stratopause
Mesosphere

A
  • temp decreases with altitude
  • temp decrease pauses
  • temp increases with altitude
  • temp increase pauses
  • temp decreases with altitude
20
Q

Winds

A

Air pressure differences result in pressure differentials
Flows along pressure gradient from areas of high pressure to areas of low pressure (vertical and horizontal axes)
Wind is horizontal air flow, across isobars perpendicularly from high to low
- Closely spaced isobars indicates greater wind speed

21
Q

Pressure gradient force

A

Attempts to equalize pressure differentials, force air flows from high to low pressure
Map line defining high- and low- pressure air cells = isobars and connect areas of equal pressure
- Winds are deflected to right/starboard (Northern hemi) or left/port (Southern hemi) by Coriolis effect
- Friction with surface results in a flow across isobars at an angle

22
Q

Anticyclones

A

High pressure air zones with nearly circular isobars, middle isobar highest
- Air aloft sinks and flows out at ground
- Air within zone sinks and spreads out
- Northern hemi: blows clockwise, Southern hemi: CCW

23
Q

Cyclones

A

Low pressure air zones with nearly circular isobars, middle isobar lowest
- Ground air flows in and rises aloft
- @ ground, air flows into and collides at low pressure zone where it rises
- CCW (Northern) CW (Southern) surface winds

24
Q

General Circulation of Atmosphere: Low Latitudes

A
  • Hadley cells circulate @ equator from solar radiation
  • Warm, moist equatorial air rises at Intertropical Convergence Zone (ITCZ), then cools and drops condense moisture in tropics (location changes w/ seasons)
  • Cooled ry air spreads and sinks @ 30N and 30S, warming adiabatically
  • Some descending air moves poleward as westerlies, some flows equatorward as trade winds
  • Dry air picks up moisture along surface -> many great deserts in this region
25
Q

General Circulation of Atmosphere: High Latitudes

A
  • Cold, dense polar air moves along surface to lower lats
  • Collides with warmer air @ 60N lats
  • Warm air from westerlies rises at about 60, drives the Polar cell
  • Top of polar cell is high altitude and the air cools before reaching the poles where it descends creating polar high pressure zones that flows as polar easterlies along the surface of both hemis
26
Q

General Circulation of Atmosphere: Middle Latitudes

A
  • Ferrel cells b/w Hadley and Polar cells are driven by their adjacent cells, not by thermal loops
  • Surface westerlies flow poleward from 30 to about 60
  • convergence with polar easterlies at polar front where colder, denser polar easterlies flow under westerlies
  • convergence of warm and cold, high and low pressure systems in midlats is turbulent -> severe weather as systems exchange energies
27
Q

Air masses

A
  • Large bodies of air with little moisture or temp variation
28
Q

Air masses in North America

A
  • Cold polar air masses, warm tropical air masses
  • dry air masses form over land, moist air masses form over ocean
  • dominant air-mass movement is W to E
  • Pacific ocean air masses have more impact than Atlantic ocean
29
Q

Fronts

A
  • Sloping surface boundaries separating air masses that differ in temp and moisture, can trigger severe weather and violent storms
30
Q

Cold front

A

cold air mass moves in and under warm air mass, lifting it up (tall clouds, thunderstorms)

31
Q

Warm front

A

warm air flows up and over cold air mass (widespread clouds)

32
Q

Jet streams

A

Narrows bands of high-velocity winds (~200kph) flowing from W to E @ high alt
- Warm air: higher pressure aloft than cold air
- Cold air: lower pressure aloft than warm air
= warm air flows S to N (North hemi)
- Coriolis effect deflects poleward airflow into 2 high-speed easterly jets
- Spin of earth turns poleward air flows to high-speed jet streams wind from W

33
Q

Subtropical jet:

A

~30N, stable path

34
Q

Polar jet

A

More powerful, ~60N, variable path

35
Q

Troughs and Ridges (Northern Hemi)

A

Meanders in polar-front jet stream may help to create rotating air bodies
- Trough of lower pressure (concave northward bend), flows core of cyclone (CCW flow)
- Ridge of higher pressure (convex northward bend), forms core of anticyclone (CW flow)

36
Q

Observed Circulation of the Atmosphere

A

Significant variation of air pressure and wind patterns by hemisphere and season
- Weaker seasonal changes in Southern Hemi - mostly ocean

37
Q

Observed Circulation of the Atmosphere: Northern Hemi

A

Winter: strong high-pressure air masses of cold air over continents
Summer: lows over continents, Pacific, highs over Bermuda

38
Q

General Circulation of the Oceans

A
  • Surface and near-surface ocean water absorb and store huge amounts of solar energy
  • Some solar heat transferred deeper by tides and winds
  • Surface and deep-ocean circulation transfers heat throughout oceans, affects global climate
39
Q

Surface Circulation of the Oceans

A
  • Mostly driven by winds
  • Movement of top layer of H2O drags on lower layer, and so on, moving H2O to depth of ~100m
  • Carries heat from low lats toward poles
  • Heat carried toward Europe in Atlantic significantly warms their climate
40
Q

Wind-driven flow directions are modified by

A

Coriolis effect and deflection off continents

41
Q

Deep Ocean Circulation

A

Oceans: layered bodies of H2O with progressively denser layers going deeper
- Water density increased by lower temp and higher dissolved salt content
- Deep-ocean water flow is thermohaline (from heat, salt) flow: overturning circulation

42
Q

Ocean water has higher density at:

A
  • High lats (low temp)
  • Arctic and Antarctic (Freshwater frozen in sea ice, remaining water = saltier)
  • Warm climates (freshwater evaporated, remaining water = saltier)
    Densest ocean water forms in northern Atlantic Ocean and Southern Ocean

goph375 (10 decks)

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