G_Pressure and Winds Activity
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School
Jacksonville University *
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Course
200
Subject
Geography
Date
Apr 3, 2024
Type
docx
Pages
6
Uploaded by MinisterDugongMaster2147
1
Names: Caleb Lieber
Group Number:
Activity
-
Atmospheric Pressure and Wind
Introduction
This activity will provide the student with the opportunity to become familiar with the concepts introduced in this uint on pressure and wind. Students will review the elements of pressure and its effect on global circulation and weather patterns.
Materials needed: textbook, atlas, pencil, calculator, colored pencils, and World Map (last page)
Part I. Atmospheric Pressure and Wind
The atmosphere (air) does weigh something and this weight exerts force or pressure on all surfaces. At Sea Level air presses down at an average of 14.7 lbs. per square inch.Around the globe, air is either rising (warm air) or sinking (cool air), in response to temperature variations. If air is sinking, the weight of the atmosphere above is increased and the atmospheric pressure is said to be high (high pressure). Conversely, if the surrounding air is rising, the weight of the atmosphere above is decreased and the atmospheric pressure is low (low pressure). If air is rising in some places and sinking in others, the sinking air must flow back to places where the air is rising in order to balance global atmospheric pressure. Thus, air always flows from areas of high pressure (sinking air) to areas of low pressure (rising air). This horizontal movement of air is known as advection
, or wind. Atmospheric pressure, also known as barometric pressure, is measured with a barometer. Different types of barometers are used and they measure pressure
in different units. Some barometers measure pressure in lbs. per square inch or in inches of mercury, as differing
weights of air will push
mercury up a glass tube
to differing heights.
Other barometers measure the pressure of
the atmosphere in SI units called millibars (mb). The average atmospheric pressure
at Sea Level on earth is
14.7 lbs. per square inch, 29.92 inches of mercury or 1013.25 millibars (mb).
Image source: Christopherson, R.W., 1994: Geosystems: An Introduction to Physical Geography
2
A.
Using the graph paper below, plot the data from Table 1. These data are pressures in relationship to altitude for a "standard atmosphere." Connect your points with a line. The curve
you will draw shows how pressure changes as altitude increases.
Table 1
Standard Barometric Pressures at
specified heights above sea level
Height (km)
Pressure (mb)
0
1013.25
1
899
3
701
5
540
7
411
10
264
20
55
30
12
40
3
50
1
1.
Describe what you see in terms of the relationship between height and pressure. Be sure to comment on the rate of change with altitude. 2.
Using the following locations and what you learned above, answer the following.
a.
Which location would have the lowest standard barometric pressure? b.
Which location would have the highest standard barometric pressure? Lewis Hills, Newfoundland (2,672 ft) Mt. Hood, Oregon (2.13 miles) Humphrey’s Peak, Arizona (12,633 ft)
Cheyenne, Wyoming (6,100 ft) Mt. McKinley, Alaska (20,320 ft)
Mt. Mitchell, North Carolina (2,040 meters)
3
3.
The map below is a simplified weather map of the United States showing surface pressure
conditions in milibars. Draw in all the appropriate isobars at 4mb intervals. Your highest
isobar value will be 1028 mb. Label each isobar. There is one high pressure center and one
low pressure center on the map - label each ("H" or "L"). Begin by darwing your 1020 mb
isobar that will run from northeast to southwest across the middle of the country; next
enclose the high pressure center; finally, enclose the low pressure area.
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