Chapter 4 Atmospheric and Oceanic       CirculationOr: What goes around, comes around.
Air Pressure and Wind
Air Pressure and Wind
Have you ever noticedchanges in air pressure?
Have you ever noticedchanges in air pressure?
Have you ever noticedchanges in air pressure?
What is air pressure?
What is air pressure?Pressure is the force a gas exerts on some specified areaof a container--it is the result of molecula...
Air pressure changes with altitude, fromplace to place—and even in the same place,changes over time
Air pressure changes with altitude, fromplace to place—and even in the same place,changes over time
Pressure, Density, and Temperature       Pressure (P), density (D), and temperature        (T) are all interrelated      ...
Changing Density Pt.I• There are three ways to change  the density of a gas: 1.Change the size of the container      What ...
Changing Density—Pt. II2. Add or subtract moleculesWhat happens to the temperature of the balloon when it’s blown up?What ...
   What happens when you change the    temperature of a confined gas?   Let’s take our original container full of    mol...
- What’s happening to the pressure?- Is density changing, or not?
A little simplification:   For confined gases:                 (if D↑ then P↑)                 (if D↑ then T↑)           ...
Changing Density—Pt.III3. Change its  temperature (if it is  uncontained)    - What will happen    to the density?    - Ho...
Changing Density—Pt.III3. Change its  temperature (if it is  uncontained)    - What will happen    to the density?    - Ho...
In the atmosphere, gases areuncontained, like this…
A little more simplification:   For unconfined gases (like in the    atmosphere):             (if T↑ then D↓)            ...
MeasuringAtmospheric Pressure
MeasuringAtmospheric Pressure   In 1643 Evangelista Torricelli (a student    of Galileo) invented the first barometer…
MeasuringAtmospheric Pressure   In 1643 Evangelista Torricelli (a student    of Galileo) invented the first barometer…
MeasuringAtmospheric Pressure   In 1643 Evangelista Torricelli (a student    of Galileo) invented the first barometer…  ...
MeasuringAtmospheric Pressure   In 1643 Evangelista Torricelli (a student    of Galileo) invented the first barometer…  ...
Average Sea Level AirPressure   29.92 in. (inches of mercury)   14 lbs/in2   1013.2 mb (millibars of mercury)   101.32...
Isobars   Lines on a map that connect points of    equal barometric pressure are called    isobars   Isobars follow the ...
Isobaric Maps
Isobaric Maps
The Pressure Gradient Force
Wind   Wind—Air moving horizontally in    response to pressure differences   The process is called advection
Convection Cell Diagram   Draw the convection cell diagram and    label it, just like you see it on the board   Practice...
   Air always moves from regions of    higher air pressure to regions of    lower air pressure   In other words:      “O...
Local WindsConvection Cells in Motion   Land and Sea Breezes   Mountain and Valley Winds   Katabatic Winds (a.k.a. Mist...
Wind Direction
Wind Direction   Wind direction is determined by where    the wind is coming from
Wind Direction   Wind direction is determined by where    the wind is coming from       For example, an east wind is one...
Wind Direction   Wind direction is determined by where    the wind is coming from       For example, an east wind is one...
Sea Breeze
Land Breeze
Valley Breeze
Mountain Breeze
Chinook/Santa Ana Winds
3 Forces Affecting Air inMotion Pressure Gradient Force Coriolis Force Friction
Force #1:The Pressure Gradient Force
Force #1:The Pressure Gradient Force   The pressure gradient force is the force    exerted by a gas (in this case, air) a...
Force #1:The Pressure Gradient Force   The pressure gradient force is the force    exerted by a gas (in this case, air) a...
Force #1:The Pressure Gradient Force   The pressure gradient force is the force    exerted by a gas (in this case, air) a...
Where the Isobars are Close Together,Winds are Faster & Stronger
Where the Isobars are Close Together,  Winds are Faster & StrongerHEY… Hold ON.    What’s UP with the curving motion?
Force #2:The Coriolis Force   A force which causes fluids in motion    over great distances and objects    moving at high...
PGF + Coriolis Force =                    “curving” wind
Coriolis Force—doing the math   The Coriolis force is a force existing in a    rotating coordinate system with constant  ...
Formulae                (for the mathematically advanced)   In non-vector terms: at a given rate of rotation of the obser...
   A force which causes fluids (and air) in    motion over great distances and objects    moving at high speed to be defl...
Coriolis Force: In The Toilet   Is it valid to assume that the water in    your toilet, sink, or bathtub will be    defle...
   A force which causes fluids in motion    over great distances and objects    moving at high speed to be deflected    ...
   A force which causes fluids in motion    over great distances and objects    moving at high speed to be deflected    ...
Geostrophic Winds
Geostrophic Winds   When the Coriolis Force and Pressure    Gradient Force balance one another,    winds spin around a hi...
Geostrophic Winds   When the Coriolis Force and Pressure    Gradient Force balance one another,    winds spin around a hi...
Geostrophic Winds   When the Coriolis Force and Pressure    Gradient Force balance one another,    winds spin around a hi...
Geostrophic winds
Force #3:Friction
Putting it together:3 Forces Affecting Air in Motion
Putting it together:3 Forces Affecting Air in Motion
Surface winds:Make a simple drawing
Surface winds:Make a simple drawing   Be able to draw it in your sleep...
Northern Hemisphere andSouthern Hemisphere Winds
Convergent and Divergent Air
Hadley Cells
A Simplified Global Circulation            Model
The ITCZ
Subtropical Highs
Some are so prominent, they even  have their own special names
Between the ITCZ and the SHPs     are the Trade Winds
The Hadley Cell at Work
The Westerlies
Subpolar Lows
Polar Easterlies
Polar Highs
A Simplified Global Circulation            Model
The Jet Stream(s)
Rossby Waves:Undulations in the Jet Stream
World Regions with Monsoon Patterns
Monsoons in India and Asia
Minor Monsoons: Australia and W. Africa
Seasonal Movement of the ITCZ
Seasonal Pressure ChangesCause Seasonal Wind Changes
ITCZ shifts more dramatically over   land than it does over water
Multi-year Atmospheric Oscillations• ENSO--El Niño-Southern Oscillation  – Ocean-Atmosphere connection     • (we will disc...
El Niño/Southern Oscillation(ENSO)
El Niño/Southern Oscillation(ENSO)
NAO--Positive Phase• Stronger Azores  high and deeper  Icelandic low• Stronger winter  storms, more of  them to the north•...
NAO--Negative Phase• Weaker Azores  high, Icelandic low• Reduced PGF =  weaker storms and  less of them• Cold snaps in  ea...
Ocean Currents• Forces driving ocean currents  – Frictional drag of wind  – Coriolis force  – Temperature, density, and sa...
Warm and Cold Surface Currents • Direction and temperature
Upwelling Currents• Where the net movement of water is away  from the coast, cold, dense water rises up  from the bottom o...
Downwelling Currents• Where the net movement of water is  toward the coast, warmer surface water  piles up and pushes down...
Open-ocean Upwelling• Near the equator,  upwelling occurs  where surface winds  cause ocean water to  diverge. As surface ...
Currents: Thermohaline Circulation
GEOG100--Lecture 06--Atmospheric and ocean circulation
Upcoming SlideShare
Loading in …5
×

GEOG100--Lecture 06--Atmospheric and ocean circulation

3,431 views

Published on

Published in: Education, Business, Technology
0 Comments
3 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
3,431
On SlideShare
0
From Embeds
0
Number of Embeds
1,648
Actions
Shares
0
Downloads
0
Comments
0
Likes
3
Embeds 0
No embeds

No notes for slide
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • \n
  • GEOG100--Lecture 06--Atmospheric and ocean circulation

    1. 1. Chapter 4 Atmospheric and Oceanic CirculationOr: What goes around, comes around.
    2. 2. Air Pressure and Wind
    3. 3. Air Pressure and Wind
    4. 4. Have you ever noticedchanges in air pressure?
    5. 5. Have you ever noticedchanges in air pressure?
    6. 6. Have you ever noticedchanges in air pressure?
    7. 7. What is air pressure?
    8. 8. What is air pressure?Pressure is the force a gas exerts on some specified areaof a container--it is the result of molecular collisionsbetween the gas and the container
    9. 9. Air pressure changes with altitude, fromplace to place—and even in the same place,changes over time
    10. 10. Air pressure changes with altitude, fromplace to place—and even in the same place,changes over time
    11. 11. Pressure, Density, and Temperature  Pressure (P), density (D), and temperature (T) are all interrelated  Pressure is the force of molecular collisions per unit area (lbs/in2)  Density is the weight of a material per unit volume (g/m2)  Temperature is a measure of molecular motion  Changes to one of these variables can cause changes in the others For example….
    12. 12. Changing Density Pt.I• There are three ways to change the density of a gas: 1.Change the size of the container What happens to pressure? What happens to temperature?
    13. 13. Changing Density—Pt. II2. Add or subtract moleculesWhat happens to the temperature of the balloon when it’s blown up?What happens to the pressure inside the balloon when it’s blown up?What happens to the pressure when it’s let go?
    14. 14.  What happens when you change the temperature of a confined gas? Let’s take our original container full of molecules and heat it up!
    15. 15. - What’s happening to the pressure?- Is density changing, or not?
    16. 16. A little simplification: For confined gases: (if D↑ then P↑) (if D↑ then T↑) (if P↑ then T↑) (if T↑ then P↑--but only if confined) Note:(changing T will NOT affect D, if confined)
    17. 17. Changing Density—Pt.III3. Change its temperature (if it is uncontained) - What will happen to the density? - How will pressure be affected?
    18. 18. Changing Density—Pt.III3. Change its temperature (if it is uncontained) - What will happen to the density? - How will pressure be affected?
    19. 19. In the atmosphere, gases areuncontained, like this…
    20. 20. A little more simplification: For unconfined gases (like in the atmosphere): (if T↑ then D↓) (if D↓ then P↓) (if D↓ then T↓)
    21. 21. MeasuringAtmospheric Pressure
    22. 22. MeasuringAtmospheric Pressure In 1643 Evangelista Torricelli (a student of Galileo) invented the first barometer…
    23. 23. MeasuringAtmospheric Pressure In 1643 Evangelista Torricelli (a student of Galileo) invented the first barometer…
    24. 24. MeasuringAtmospheric Pressure In 1643 Evangelista Torricelli (a student of Galileo) invented the first barometer… Today, we use an aneroid barometer
    25. 25. MeasuringAtmospheric Pressure In 1643 Evangelista Torricelli (a student of Galileo) invented the first barometer… Today, we use an aneroid barometer
    26. 26. Average Sea Level AirPressure 29.92 in. (inches of mercury) 14 lbs/in2 1013.2 mb (millibars of mercury) 101.32 kPa (kilopascals, where 1 kilopascal is equivalent to 10 millibars) We will use millibars, as this is the most commonly used unit of measurement
    27. 27. Isobars Lines on a map that connect points of equal barometric pressure are called isobars Isobars follow the same rules as other iso- lines (don’t cross, form closed shapes, etc.)
    28. 28. Isobaric Maps
    29. 29. Isobaric Maps
    30. 30. The Pressure Gradient Force
    31. 31. Wind Wind—Air moving horizontally in response to pressure differences The process is called advection
    32. 32. Convection Cell Diagram Draw the convection cell diagram and label it, just like you see it on the board Practice drawing a simplified version to help you remember “out of the high, into the low” on exam day
    33. 33.  Air always moves from regions of higher air pressure to regions of lower air pressure In other words: “Out of the High, Into the Low!”
    34. 34. Local WindsConvection Cells in Motion Land and Sea Breezes Mountain and Valley Winds Katabatic Winds (a.k.a. Mistral) Chinook Winds (a.k.a. Santa Anas, Diablo Winds, Foehn winds, etc.)
    35. 35. Wind Direction
    36. 36. Wind Direction Wind direction is determined by where the wind is coming from
    37. 37. Wind Direction Wind direction is determined by where the wind is coming from  For example, an east wind is one that is coming from the east
    38. 38. Wind Direction Wind direction is determined by where the wind is coming from  For example, an east wind is one that is coming from the east  A sea breeze is one that is coming from the sea and moving toward the land
    39. 39. Sea Breeze
    40. 40. Land Breeze
    41. 41. Valley Breeze
    42. 42. Mountain Breeze
    43. 43. Chinook/Santa Ana Winds
    44. 44. 3 Forces Affecting Air inMotion Pressure Gradient Force Coriolis Force Friction
    45. 45. Force #1:The Pressure Gradient Force
    46. 46. Force #1:The Pressure Gradient Force The pressure gradient force is the force exerted by a gas (in this case, air) at higher pressure trying to move to an area of lower pressure
    47. 47. Force #1:The Pressure Gradient Force The pressure gradient force is the force exerted by a gas (in this case, air) at higher pressure trying to move to an area of lower pressure The PGF pulls air out of the high and into the low at a 90º angle relative to the isobars
    48. 48. Force #1:The Pressure Gradient Force The pressure gradient force is the force exerted by a gas (in this case, air) at higher pressure trying to move to an area of lower pressure The PGF pulls air out of the high and into the low at a 90º angle relative to the isobars The greater the “slope”, or gradient, between one pressure region and the next, the faster the air will move
    49. 49. Where the Isobars are Close Together,Winds are Faster & Stronger
    50. 50. Where the Isobars are Close Together, Winds are Faster & StrongerHEY… Hold ON. What’s UP with the curving motion?
    51. 51. Force #2:The Coriolis Force A force which causes fluids in motion over great distances and objects moving at high speed to be deflected:  to the right in the Northern Hemisphere  to the left in the Southern Hemisphere. (Note: Air acts like a fluid in many ways.)
    52. 52. PGF + Coriolis Force = “curving” wind
    53. 53. Coriolis Force—doing the math The Coriolis force is a force existing in a rotating coordinate system with constant angular velocity to a reference frame. It acts on a body moving in the rotating frame to deflect its motion sideways.
    54. 54. Formulae (for the mathematically advanced) In non-vector terms: at a given rate of rotation of the observer, the magnitude of the Coriolis acceleration of the object is proportional to the velocity of the object and also to the sine of the angle between the direction of movement of the object and the axis of rotation. The vector formula for the magnitude and direction the Coriolis acceleration is where (here and below) is the velocity of the particle in the rotating system, and is the angular velocity vector (which has magnitude equal to the rotation rate and is directed along the axis of rotation) of the rotating system. The equation may be multiplied by the mass of the relevant object to produce the Coriolis force: The × symbols represent cross products. (The cross product does not commute: changing the order of the vectors changes the sign of the product.) The Coriolis effect is the behavior added by the Coriolis acceleration. The formula implies that the Coriolis acceleration is perpendicular both to the direction of the velocity of the moving mass and to the rotation axis.
    55. 55.  A force which causes fluids (and air) in motion over great distances and objects moving at high speed to be deflected  to the right in the Northern Hemisphere  to the left in the Southern Hemisphere.
    56. 56. Coriolis Force: In The Toilet Is it valid to assume that the water in your toilet, sink, or bathtub will be deflected to the right while draining?
    57. 57.  A force which causes fluids in motion over great distances and objects moving at high speed to be deflected  to the right in the Northern Hemisphere  to the left in the Southern Hemisphere.
    58. 58.  A force which causes fluids in motion over great distances and objects moving at high speed to be deflected  to the right in the Northern Hemisphere  to the left in the Southern Hemisphere.
    59. 59. Geostrophic Winds
    60. 60. Geostrophic Winds When the Coriolis Force and Pressure Gradient Force balance one another, winds spin around a high or low pressure cell, parallel to the isobars
    61. 61. Geostrophic Winds When the Coriolis Force and Pressure Gradient Force balance one another, winds spin around a high or low pressure cell, parallel to the isobars These winds occur in the upper atmosphere, where there is no friction
    62. 62. Geostrophic Winds When the Coriolis Force and Pressure Gradient Force balance one another, winds spin around a high or low pressure cell, parallel to the isobars These winds occur in the upper atmosphere, where there is no friction They are known as geostrophic winds
    63. 63. Geostrophic winds
    64. 64. Force #3:Friction
    65. 65. Putting it together:3 Forces Affecting Air in Motion
    66. 66. Putting it together:3 Forces Affecting Air in Motion
    67. 67. Surface winds:Make a simple drawing
    68. 68. Surface winds:Make a simple drawing Be able to draw it in your sleep...
    69. 69. Northern Hemisphere andSouthern Hemisphere Winds
    70. 70. Convergent and Divergent Air
    71. 71. Hadley Cells
    72. 72. A Simplified Global Circulation Model
    73. 73. The ITCZ
    74. 74. Subtropical Highs
    75. 75. Some are so prominent, they even have their own special names
    76. 76. Between the ITCZ and the SHPs are the Trade Winds
    77. 77. The Hadley Cell at Work
    78. 78. The Westerlies
    79. 79. Subpolar Lows
    80. 80. Polar Easterlies
    81. 81. Polar Highs
    82. 82. A Simplified Global Circulation Model
    83. 83. The Jet Stream(s)
    84. 84. Rossby Waves:Undulations in the Jet Stream
    85. 85. World Regions with Monsoon Patterns
    86. 86. Monsoons in India and Asia
    87. 87. Minor Monsoons: Australia and W. Africa
    88. 88. Seasonal Movement of the ITCZ
    89. 89. Seasonal Pressure ChangesCause Seasonal Wind Changes
    90. 90. ITCZ shifts more dramatically over land than it does over water
    91. 91. Multi-year Atmospheric Oscillations• ENSO--El Niño-Southern Oscillation – Ocean-Atmosphere connection • (we will discuss this phenomenon in Chapter 7)• NAO--North Atlantic Oscillation – Affects Europe, eastern US, Greenland/ Canada region; no defined pattern• AO--Arctic Oscillation – Associated with NAO• PDO--Pacific Decadal Oscillation 70
    92. 92. El Niño/Southern Oscillation(ENSO)
    93. 93. El Niño/Southern Oscillation(ENSO)
    94. 94. NAO--Positive Phase• Stronger Azores high and deeper Icelandic low• Stronger winter storms, more of them to the north• Mild, wet eastern U.S.; warm, wet in N. Europe• Cold, dry Med., west Greenland, NE Canada 72
    95. 95. NAO--Negative Phase• Weaker Azores high, Icelandic low• Reduced PGF = weaker storms and less of them• Cold snaps in eastern U.S. bring more snow; cold, dry in N. Europe• Wetter Med.; Greenland, NE Canada milder 73
    96. 96. Ocean Currents• Forces driving ocean currents – Frictional drag of wind – Coriolis force – Temperature, density, and salinity differences – Location of contents and shape of the sea floor – Tides 74
    97. 97. Warm and Cold Surface Currents • Direction and temperature
    98. 98. Upwelling Currents• Where the net movement of water is away from the coast, cold, dense water rises up from the bottom of the ocean to replace the water that has moved away. 76
    99. 99. Downwelling Currents• Where the net movement of water is toward the coast, warmer surface water piles up and pushes down toward the bottom of the ocean, displacing colder water, below. 77
    100. 100. Open-ocean Upwelling• Near the equator, upwelling occurs where surface winds cause ocean water to diverge. As surface waters move apart, cold bottom water rises up to replace what’s been pushed away. 78
    101. 101. Currents: Thermohaline Circulation

    ×