Field Maps
Topic 4
Field Maps
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Field maps show a certain value over a given
space. Examples of field include temperature,
pollution, noise, elevation, etc.
Isolines are lines drawn to connect values that
are the same.
Isotherms – equal temperature
Isobars – equal atmospheric pressure
Contour lines – equal elevation
Drawing Isolines
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Connect equal values
Infer where values may be. 10 would be
between 5 and 15.
The interval is the difference in value between
lines. This value must remain constant.
Isotherms connect equal temperature.
Isolines Notes
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Isolines “never” cross
If isolines are closer together, rate of change
will be greater
If isolines are further apart, rate of change will
be less.
Gradient = Change in value
Distance
Topographic Maps
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Contour maps are field maps where elevation
is the value measured.
Contour lines only cross if there is a cliff
Contour lines bend upstream when there is a
river. V’s point upstream
Closer contour lines – steeper gradient
Maximum elevation is one less than next
contour line.
The V’s are
due to
erosion by
the river.
The V’s
point
upstream.
Depressions
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Depressions are indicated with hatchur marks
on the contour lines.
First hatchur line and last elevation line must
be equal.
The interval remains the same.
Minimum elevation is one more than next
lower hatchur line.
Topographic Profiles
A profile is a side view of a topographic
map.
How to Make a Profile
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Write values for each isoline that crosses the
profile line.
Place a piece of scrap paper from point to
point.
Mark the paper and include the values.