The Current Climate of the Earth

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The Current Climate of the Earth
2
Large Scale Energy Transfers

• The circulation we see in the Earths atmosphere
  and oceans is the result of an unequal
  distribution of energy.
• The tropics receive more solar radiation while
  the higher latitudes receive less.
• The temperature is higher near the earths
  surface and colder at greater heights.

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Large Scale Energy Transfers (Cont.)

• The Second Law of Thermodynamics includes a
  statement that energy is transferred from regions
  of surplus to regions of deficit.

4
Large Scale Energy Transfers

• Hadley cells
• Surface highs and lows
• Upper level ridges and troughs
• Surface ocean currents

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Energy Transfers by the Hadley Cells

• (1) The trade winds blow from the subtropical
  highs into the ITCZ transfer latent energy toward
  the equator.
• (2) The circulation around the Hadley cell
  creates the very hot temperatures over the
  subtropical deserts. This represents a poleward
  transfer of internal energy.

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tropopause
Sinking air warms at DALR
Air cools at SALR
Hadley Cell
Air cools at DALR
The trade winds blow the water vapor into the
ITCZ which represents a transfer of latent energy
toward the equator.
Subtropical High
ITCZ
Water evaporates as the tropical oceans absorb
solar radiation
High temperatures at surface represent a poleward
transfer of internal energy
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Energy Transfers by Surface Pressure Systems

• Over a long period of time the mass of air
  traveling northward must equal the mass of air
  traveling southward must be equal.
• Generally the air moving poleward is warmer and
  contains more water vapor than air moving toward
  the equator.

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Energy Transfers by Surface Pressure Systems
(Cont.)

• In the northern hemisphere southerly winds
  transfer large magnitudes of internal energy and
  latent energy toward the pole.
• Northerly winds transfer much less internal
  energy and latent energy toward the equator.

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Energy Transfers by Surface Pressure Systems
(Cont.)

• The net result is that surface pressure systems
  transfer both internal energy and latent energy
  toward the pole.

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The result is a net transfer of internal energy
and latent energy toward the north pole.
N
H
L
E
Northerly winds transfer cool, dry air toward the
south.
This air contains much more internal energy and
latent energy.
This air contains much less internal energy and
latent energy.
Southerly winds transfer warmer moister air
toward the north.
L
H
11
Energy Transfers by Upper Level Ridges and Troughs

• The flow around upper level ridges and troughs
  also transfers internal energy and latent energy.
• In the northern hemisphere southerly winds
  transfer larger amounts of internal energy and
  latent energy toward the pole.
• Northerly winds transfer less internal energy and
  latent energy toward the equator.

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Energy Transfers by Upper Level Ridges and
Troughs (Cont.)

• The net result is that upper level ridges and
  troughs transfer both internal energy and latent
  energy toward the pole.

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The net effect is that upper level ridges and
troughs transfer both internal energy and latent
energy toward the north pole.
Less internal energy and latent energy moves
south.
More internal energy and latent energy moves
north.
Northerly winds transfer cool, dry air toward the
equator.
Southerly winds transfer warmer moister air
toward the pole.
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Energy Transfers by Surface Ocean Currents

• The surface ocean currents, which are strongly
  influenced by the surface winds also transfer
  large magnitudes of internal energy.

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Subtropical Gyres

• Over the northern Atlantic and Pacific Oceans,
  the winds around the subtropical high pressure
  systems create large clockwise circulations of
  the surface ocean currents called subtropical
  gyres.

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Energy Transfers by Surface Ocean Currents (Cont.)

• The currents moving from south to north (e.g. the
  Gulf Stream) transfer large magnitudes of
  internal energy toward the pole.
• The currents moving from north to south (e.g. the
  Canaries Current or the California Current)
  transfer much less internal energy toward the
  equator.

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Gulf Stream (West Wind Drift)
Warm currents transfer more internal energy.
Canaries Current
Subtropical gyre
Florida Current
Cold current transfers less internal energy.
North Equatorial Current
18
Energy Transfers by Surface Ocean Currents (Cont.)

• The net effect is that the surface ocean currents
  transfer internal energy toward the pole.

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Climate Classification

• Wladimir Köppen developed a system for
  classifying the climates of the Earth based on
  the temperature and precipitation associated with
  certain major types of vegetation.

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Modified Köppen Classification

• We will used a simplified version of the Köppen
  classification in this course.

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A Climates

• A Climates are moist tropical climates.
• The average temperature of each month must be
  greater than or equal to 18C.

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Af Climates

• Af climates are tropical, wet all year round.
• Each month averages at least 6 cm (2.4 inches) of
  rainfall.
• These conditions are found near the ITCZ.

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Af Climates

• Uaupes, Brazil 0, 67W 83 m (272 ft)
• J F M A M J J
  A S O N D
• Temp. 27 27 27 27 26 26
  25 26 27 27 27 27
• (C)
• Precip. 26 20 25 27 30 23
  22 18 13 18 18 26
• (cm)

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Aw Climates

• Aw climates are tropical climates with a winter
  dry season.
• Key West, Florida 24N, 82W 7 m (22 ft)
• J F M A M J J A
  S O N D
• Temp. 21 21 23 24 26 28 29 29
  29 26 23 21
• (C)
• Precip. 5 3 3 3 9 11
  8 11 17 15 6 4
• (cm)

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Am Climates

• Am climates are tropical monsoon climates with a
  short dry season.
• Cristobal, Panama 9N, 80W 11 m (35 ft)
• J F M A M J J
  A S O N D
• Temp. 27 27 27 27 27 27 27
  27 27 27 26 27
• (C)
• Precip. 9 4 4 10 32 35 40
  39 32 40 57 30
• (cm)

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B Climates

• B climates are dry climates where the potential
  evaporation and transpiration from plants exceeds
  the precipitation that falls.

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BW Climates

• BW (note the upper case W) climates are desert
  climates which have little or no precipitation
  throughout the year.
• Las Vegas, Nevada 36N, 115W 638 m (2075 ft)
• J F M A M J J
  A S O N D
• Temp. 7 10 13 16 21 27 30
  29 24 19 12 8
• (C)
• Precip. 2 1 1 1 1 1
  1 1 1 1 1 1
• (cm)

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BS Climates

• BS (note the uppercase S) climates are steppe
  climates that have enough precipitation during
  part of the year to support dry, grasslands
  vegetation.

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BS Climates (Example)

• Cheyenne, Wyoming 41N, 105W 1872 m (6139 ft)
• J F M A M J J
  A S O N D
• Temp. -4 -3 1 5 10 16
  19 18 14 7 2 -2
• (C)
• Precip. 1 3 1 5 6 4
  5 3 3 2 1 1
• (cm)

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C Climates

• C climates are mid-latitude climates with mild
  winters.
• The average temperature of the warmest month is
  greater than 10C (50F) and the average
  temperature of the coldest month is between 18C
  (64F) and -3C (27F).
• These conditions support the growth of deciduous
  forests.

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Cf Climates

• Cf climates are warm, rainy, wet all year.
• Wilmington, N.C. 34W, 78W 22 m (72 ft)
• J F M A M J J
  A S O N D
• Temp. 9 9 13 16 21 25 26
  26 23 18 13 9
• (C)
• Precip. 8 8 8 7 8 13
  18 16 11 8 5 7
• (cm)

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Cw Climates

• Cw climates are warm with rainy summers and dry
  winters.
• Allahabad, India 25N, 82E 98 m (322 ft)
• J F M A M J J
  A S O N D
• Temp. 16 18 25 31 34 34 30
  29 29 26 20 16
• (C)
• Precip. 2 2 2 1 2 13
  32 25 21 6 1 1
• (cm)

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Cs Climates

• Cs climates (also called Mediterranean climates)
  are warm climates with dry summers.
• Sacramento, California 39N, 121W 21 m (69 ft)
• J F M A M J J
  A S O N D
• Temp. 8 10 13 15 18 21 23
  23 21 17 12 8
• (C)
• Precip. 10 7 7 4 0 0
  0 0 1 2 5 10
• (cm)

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D Climates

• D climates have cold, snowy winters.
• The average temperature of the warmest month is
  greater than 10C (50F) and the average
  temperature of the coldest month is -3C (27F).
• These conditions support the growth of coniferous
  forests.

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Df Climates

• Df climates are cold, but have ample
  precipitation during all months of the year.
• Chicago, Illinois 42N, 88W 251 m (823 ft)
• J F M A M J J
  A S O N D
• Temp. -4 -3 2 9 14 20 23
  22 19 12 5 -1
• (C)
• Precip, 5 5 7 7 9 9
  9 9 9 7 7 5
• (cm)

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Dw Climates

• Dw climates are cold climates with dry winters.
• Inchon, Korea 37N, 127E 70 m (231 ft)
• J F M A M J J
  A S O N D
• Temp. -4 -3 3 10 15 20 24
  23 19 14 6 -1
• (C)
• Precip. 2 2 3 7 9 10
  28 22 11 4 4 3
• (cm)

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E Climates

• E climates are the polar climates. They occur at
  very high latitudes where there is limited or no
  solar radiation during the year, and at higher
  elevations in mountainous regions that have
  persistent cold temperatures.

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ET Climates

• ET climates are tundra climates.
• The average temperature of the warmest month is
  between 10C (50F) and 0C (32F).

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ET Climates (Example)

• Point Barrow, Alaska 71N, 157W 7 m (22 ft)
• J F M A M J J
  A S O N D
• Temp. -27 -28 -26 -18 -8 1 4
  4 -1 -8 -17 -24
• (C)
• Precip. 0 0 0 0 0 1
  2 2 1 1 1 0
• (cm)

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EF Climates

• EF climates are frozen ice cap climates.
• The temperature of the warmest month is less than
  0C (32F).
• McMurdo Sound, Antarctica 78S, 166E 0 m (0
  ft)
• J F M A M J J
  A S O N D
• Temp. -5 -10 -16 -23 -25 -25 -26
  -26 -25 -21 -11 -5
• (C)
• Precip. 0 0 0 0 0 0
  0 0 0 0 0 0
• (cm)

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A Climates

• A climates are typically found in the lower
  latitudes (i.e. the tropics on both sides of the
  equator) which receive large amounts of solar
  radiation throughout the year.

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B Climates

• B climates are regions of sinking motion. They
  tend to be found in areas dominated by the
  subtropical high pressure systems or in the rain
  shadows of major mountain ranges.

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C Climates

• C climates occur in the middle latitudes where
  summers are warm and winters are cool. Most of
  the precipitation that falls is produced by
  extratropical cyclones.

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D Climates

• D climates occur over the continents at higher
  latitudes and tend to have cold snowy winters.
  These areas receive less solar radiation than C
  climates in winter and are farther from the
  moderating influences of the oceans.

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E Climates

• E climates are found in polar regions and at
  higher elevations in mountainous areas with snow,
  ice and glaciers. They are characterized by cold
  temperatures that are below freezing for all or
  most of the year.