Fields and Isolines !!!!
 We’re going to learn about Isolines…isn’t that
awesome???
 Whatever, just be quiet and learn.
Fields – WRITE THIS DOWN in
your notes sheet!!
 Field – a region of space in which there is a
MEASUREABLE quantity of a given property at every
point
 Examples: Temperature, Pressure, Elevation, etc.
 The strength of a field varies (Ex. Whoever smelt it..)
 The farther away from the source, the weaker the field
 Fields can be MAPPED by placing measurements on
paper and connecting locations with EQUAL readings
with figures called ISOLINES!!!
Isolines
 What the heck IS an isoline, anyway?
 An isoline is a line connecting points of equal value.
Examples of isolines:
 Isotherms:
 points of equal temperature
 Isobar:
 points of equal barometric (air) pressure
 Contour:
 points of equal altitude
 Concentration of chemicals
 Anything else you can get a value for.
 (The weather channel loves isolines!)
Rules for drawing them!
 How do you do it?
 Here’s how!! Once you learn this, you’ll be experts.
 1. Isolines connect points of equal
value.
5
5
10
10
10
10
15
15
 2. Isolines are gentle, curving lines-
no sharp corners.
5
5
10
10
10
10
15
15
 3. Isolines should always form closed
curves (loops) even though the map might
only show part of it.
 So, at times you may have to extend a line
to the edge of the map!
 4. Isolines NEVER cross- this would
mean that one point has two different
values. Ex: one spot has two
temperatures?
 That’s whack!
40 °
50 °
30 °
60 °
X
20°
Y
Z
 5. Isolines usually are parallel. (They
have a parallel trend, and usually follow
the same pattern.)
More on Isolines!!
 6) Isolines are drawn according to a designated isoline
interval
 On a map, they are called the CONTOUR INTERVAL
 7) Isolines should ALWAYS be drawn in pencil
 It’s easy to make mistakes, so you might have to do
some heavy duty erasing.
 Stop whining.
Visualizations of contour lines
 http://geology.asu.edu/~sreynolds/topo_gallery/topo_
gallery.htm
What is Gradient?
 Gradient shows how quickly the value
changes from one point to another.
Use your ESRT to write the equation
For Gradient on your notes sheet!
Anything else you should know?
 Actually, yes.
 You see…sometimes isolines are REALLY close
together
 Other times, they are kind of far apart
 Does this mean something?
 You bet!
 How can you tell whether a gradient is steep or
gentle?
 A steep (high) gradient changes quickly and the
isolines are close together.
 A gentle (low) gradient changes slowly and the lines
are far apart.
Steep area
Gentle area
OK Let’s practice.
 We are going to do some isoline practice now
 Take out that isoline packet I handed out at the
beginning of the period.
 Hurry!
 Ok, here we go.
Highlight
data
points.
Fill in
gaps in
data.
Connect
the dots.
Go on
to the
next
value.
Drawing Isolines II
Drawing Isolines III