Atmospheric Pressure and Wind

1
Atmospheric Pressureand Wind

• Atmospheric Circulation
• Air Pressure
• Air Pressure and Temperature
• Measurement of Pressure
• Pressure Gradient
• The Sea Breeze
• Chapters 6.0 6.1 7.0 7.1

2
Atmospheric Circulation
____________________________

• The atmospheric circulation is concerned with the
  large-scale air flow patterns of the whole Earth
• In addition to providing our winds, the general
  circulation serves to redistribute latitudinal
  imbalances of energy and moisture

3
Atmospheric Circulation
____________________________
Relates to Figure 7.3
Strahler and Strahler Introducing Physical
Geography
4
Atmospheric Circulation
____________________________

• The atmospheric circulation is responsible for
  the transfer of approximately 60 65 of the
  energy from the equator to the poles

5
Air Pressure
____________________________

• The force exerted by the weight of a column of
  air above a given point
• Air pressure is proportional to density
• High density, then high air pressure
• Low density, then low air pressure
• Air pressure decreases with an increase in
  altitude

6
Air Pressure
____________________________
Not in Book
7
Air Pressure
____________________________
Not in Book
8
Air Pressure and Temperature
____________________________

• Air pressure is also proportional to air
  temperature
• Cold air is denser, and has higher air pressure
• Warmer air is less dense, and has lower air
  pressure

9
Air Pressure and Temperature
____________________________

• High air pressure is associated with lower
  temperatures
• Low air pressure is associated with higher
  temperatures

10
Measurements of Pressure
____________________________

• Air pressure is measured by an instrument called
  a barometer

11
The Barometer
____________________________
Not in Book
12
Measurements of Pressure
____________________________

• In climatology, air pressure is typically
  expressed in millibars
• A line on a map connecting equal areas of
  pressure is an isobar

13
Measurements of Pressure
____________________________
Figure 6.1.a
14
Measurements of Pressure
____________________________
Not in Book
15
Measurements of Pressure
____________________________
Not in Book
16
Pressure Gradient
____________________________

• A pressure gradient is the amount of pressure
  change occurring over a given distance
• Air tends to mover from areas of high pressure to
  areas of low pressure, until the air pressures
  are equal

17
Pressure Gradient
____________________________
Not in Book
18
The Sea Breeze
____________________________

• An example to illustrate how temperature
  differences can generate a pressure gradient, and
  thereby create winds.

19
The Sea Breeze
____________________________
Not in Book
20
The Sea Breeze
____________________________
Not in Book
21
The Sea Breeze
____________________________
Not in Book
22
The Sea Breeze
____________________________

• Some main points
• Temperature variations created pressure
  differences
• The pressure differences initiated the flow of
  wind

23
The Sea Breeze
____________________________

• A sea breeze is a small-scale analogy of
  larger-scale processes
• Horizontal pressure gradient is the driving force
  of wind

24
(No Transcript)