Transcript The Earth System

Chapter 5 study guide
1. Describe the relationship between atmospheric pressure
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and elevation.
Describe the relationship between temperature and
atmospheric pressure.
Describe an isobar.
What is wind? Describe the function of the wind on the
earth.
What two factors influence wind direction? How do these
factors function to influence wind direction?
How are winds named? Define windward, leeward and
prevailing winds.
Describe the idealized model of Earth’s pressure and wind
systems. (Figure 5.12)
Study Guide Chapter 5
8. Define gyres.
9. Describe the effects of seasonal migration in
California.
10. What is El Nino?
11. Describe local winds in our area. (land breezesea breeze, Santa Ana winds, mountain & valley
breezes)
12. Describe the upper air wind system.
Weight of the Atmosphere
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The atmosphere
exerts a pressure of
14.7lbs/sq in. (1034
grams/cm)
Atmospheric
pressure is important
because variation in
pressure causes our
atmospheric
circulation
Pressure Units
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Meteorologists prefer to
work in millibar (mb) units
Standard sea-level
pressure of 1013.2 mb will
cause mercury to rise to
76 cm or 29.92 inches. See
Fig. 5.1 text.
Variations in Air Pressure
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Air pressure decreases
with elevation
Humans not generally
sensitive to small
variations in air
pressure
Mapping Pressure Distribution
Isobar = lines of equal pressure
The air moves down a pressure gradient.
Just like water rolling down a hill from high
to low elevation.
Low Atmospheric Pressure
High Atmospheric Pressure
Which is High Pressure Which is Low?
Fig 5.3
Cyclones and Anticyclones
Horizontal Variation in Air Pressure
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5.13
Unequal distribution
of insolation results
in uneven heating of
planet. Pressure and
temperature.
relationship?
Other factors include:
differential heating of
land and water,
different albedos of
surfaces
Wind
Wind is the horizontal movement of air.
Winds are named from the direction they
are coming from. A North
wind is coming from the North.
Fig. 5-7, p. 121
Winds are transportation for
energy and moisture. Winds are an attempt
to keep the Earth’s temperature in
equilibrium.
Fig. 5-13, p. 127
Fig. 5-15, p. 130
Global Wind Systems
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Subtropical High Pressure
 Source of Trade Winds and Westerlies
 Horse Latitudes
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Trade Winds
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50-250 N and S
Northeast and Southeast Trades
Pilots flying West
Hawaiian islands pleasant
Global Wind Systems
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ITC (Intertropical Convergence Zone)
 Doldrums (50N-50S)
 Winds converge
 Weak winds
Idealized model
 Changes due to land and ocean masses
 Seasonal changes-pressure belts move North
in summer.
Coriolis Effect
Surface Friction
Effects of Seasonal Migration
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5.16
Seasonal migration will
most affect those regions
near the boundary zone
between two wind or
pressure systems
California is an example of
a region located within a
zone of transition
Land and Sea Breeze
Fig. 5-9, p. 123
Mountain & Valley Breezes (local)
Mountain Breeze
Valley breeze
5.10
Local Winds
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5.11
Chinook (USA rocky
mtns)
Santa Ana- compressed
warm and dry air.
Foehn wind- Alps
p. 125
Upper Air Winds
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Include the upper air Westerlies and polar jet
streams. About 16,500 ft.
25-100 miles in width
1-2 miles in depth
“Internal ribbon of air” See Fig. 5.19
Less complex than surface winds.
Fast moving- 100 mph west to east move
weather.
Jet streams
Ocean currents
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Like winds ocean currents distribute heat and
energy of the Earth.
Surface currents that move in broad circulatory
patterns are called gyres.
Ocean currents are affected by the Coriolis
Effect, winds, salinity, and temperature.
Fig. 5.24
El Niño
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El Niño is a warm, weak counter current that replaces
the normally cold (upwelling) coastal waters
El Niño can last for many months and water
temperatures are raised for thousands of miles
Exceptionally strong El Niños impact worldwide weather
El Niño
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Sir Gilbert Walker discovers a “seesaw” pattern of air
pressure in the Pacific called the Southern Oscillation
Fig. 5-25, p. 140
Interactivity
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Envrs-chp. 6 number 3.