Unit 2: Field Maps
I Field Maps: show patterns in the
measurements made in a Field (an
area of space).
Field 1
Field 2
Field 3
A. Isolines connect the points of
equal value on a field map.
Examples:
1. Isotherms: connect points of
equal temperature. (See text p.493)
http://www.ametsoc.org/amsedu/dstreme/images/sfcptemp.gif
http://www.ametsoc.org/amsedu/dstreme/images/sfc_temp.gif
2. Isobars: connect points of equal
air pressure. (See text p.534)
http://www.ametsoc.org/amsedu/dstreme/images/sfcppres.gif
http://www.ametsoc.org/amsedu/dstreme/images/sfc_pres.gif
3. Contour Lines: connect points of
equal elevation. (see text p.14-15)
There are many other types of
isolines.
Check out all these different types:
Isolines - Geography
B. Isoline Interval: is the change in
the field measurement from one
isoline to the next.
It is not the distance between the
lines.
*The interval always remains the
same on any given map.
Ex.: Isotherm interval: 10 F.
http://www.ametsoc.org/amsedu/dstreme/images/sfc_temp.gif
Isobar interval: 4 mb.
http://www.ametsoc.org/amsedu/dstreme/images/sfc_pres.gif
C. Drawing Field Maps
http://www.mrsciguy.com/documents/isolines.ppt#284,1,Isolines
(slides 6-10)
1. Isolines do not have sharp corners.
2. Isolines connect to form a loop or
run off the page
3. Isolines do not touch or cross.
4. Isolines tend to run parallel.
isolisne practice.pdf
Here are some more practice examples; try these at home!
CONTOUR ANALYSIS
The Steve Applet
Practice Worksheets: Drawing Field Maps 1 and 2
D. Gradient is how fast the
measurements in a field are changing.
1. If the isolines are close together,
the measurement changes quickly.
This is a high gradient.
If the isolines are further apart, the
measurement changes more slowly.
This is a low gradient.
[Diagram]
2. Gradient can also be calculated.
Use this formula:
Gradient = Change in Field Value / Distance
(look at isolines)
(look at map scale)
(See ESRT p.1)
Ex. Regents example:
 Draw all the isolines on this map at an interval of 2.
 Calculate the field gradient from point A to B.
Regents Example 2:
 What is the latitude and longitude of point C to the closest
minute.
 Calculate the average ocean-floor gradient between point A
and point B. Label your answer with the correct units.
E. Topographic Maps show
elevations of the land above sea level.
(see text p.14-15- discuss)
[What is sealevel?]
shore - Google Image Search
[Diagram]
1. Contour Lines are isolines that
connect points of equal elevation.
Contour Lines and Elevation (slides 1-3)
2. Contour Interval is the
difference in elevation between two
adjacent lines.
Contour Interval =
Change in elevation / # of spaces
Contour Lines and Elevation (slide 4))
This interval is always the same on
any single map but can change on
different maps.
3. Features found on Topographic Maps:
 Hill or Mountain
Contour Lines and Elevation (slide 6)
[Diagram]
http://www.youtube.com/user/metfan869#p/u/31/p4rt6seyxIU
 High or steep Gradient (Slope)
Contour Lines and Elevation (slide 6)
[Diagram]
http://www.youtube.com/user/metfan869#p/u/24/1aBa33pi_00
 Valley
Contour Lines and Elevation (slide 7)
[Diagram]
 Rivers
Contour Lines and Elevation (slide 9)
[Diagram]
http://www.youtube.com/user/metfan869#p/u/28/k3j-zN3XVDI

Depressions or Craters use
Hachure Marks
Contour Lines and Elevation (slide 8)
[Diagram]
http://www.youtube.com/user/metfan869#p/u/20/_gwLcmXQ1_M
Contour Lines and Elevation (slides 9-12)
4. Map Profiles show how the land
looks when viewed from the side
[Diagram]
http://www.youtube.com/user/metfan869#p/u/30/dA1J9kpi1nM
Complete WS #1-3
Lab #5: Constructing a Topo Map
Lab #6: Mount St. Helens