Part I
Maps and Numbers
REPRESENTING CLIMATE DATA
 Station Models
 Isoline Maps
Station model:
an abbreviated plot of
weather station data
Station model:
abbreviation of weather station data
Station model:
Text, pp. 488-489, textbook
Pressure (without decimal point; without initial 10 or 9)(mb)
Air Temperature
Present weather
Dew point
Wind direction
Cloud
cover
Wind speed
pressure change in past 3 hrs (without decimal pt)
Cloud cover
 Circle centered on station location
scattered
overcast
Air temp; dew point temp
Air temp
Dew pt temp
Wind direction
Direction arrow points is wind direction
(direction wind is coming FROM)
If calm, no arrow and
double circle
Wind speed
“knot”
Nautical mile per hour
1 knot = 1.15 mph; 1.9 km/hr
Present weather
Current pressure
3 numbers; in mb; no decimal point;
10 or 9 at beginning of number is NOT shown
162
Does number begin with
“10” or “9” ?
162 = 1016.2 mb
 353 ?
 893?
 1035.3 mb
 989.3 mb
 175?
 074?
 1017.5 mb
 1007.4 mb
 985?
 890?
 998.5 mb
 989 mb
Pressure tendency during
past three hours
02
Amount of change; mb;
No decimal shown;
07
13
Last night
Station Model Exercise :
 In pairs:
 Pick any 4 cities and make station models.
 Each pair make 4
Isoline maps
Interpolate between discrete data points to
create a continuous “surface”:
 Helps us to visualize the data
examples:
 Elevation surface
 Pressure surface
 Temperature surface
Topographic map
an elevation surface
Contour lines
Temperature map
20
30
40
50
50
60
isotherms
Pressure surface
isobars
Isolines “connect points of
equal value”
Types of isolines:







Isobars: pressure
Isotherms: temperature
Isohyets: precipitation amount
Isodrosotherms: dew point
Isogons: wind direction
Isotachs: wind speed
Isoshears : wind shear
 All data values on an isoline are equal.
 The interval between lines is constant for the
entire map.
50
50
45
40
52
39
60
43
60
70
64
69
58
Rules for making an isoline map:
 Lower values are always on one side of isoline ; higher values on the other side .
 Isolines NEVER CROSS OR TOUCH, NEVER SPLIT .
 Isolines will generally be SMOOTH AND PARALLEL.
 LABEL each isoline on the ends for open and in the center for closed isolines.
35
35

 Interpolate between points as exactly as possible!
 Do NOT draw lines where there are no data points.
 Use a pencil
35
39
32
48
39
39
40
45
35
40
38
50
52
51
51
52
42
50
64
60
63
52
62
62
75
59
66
65
69
74
62
71
78
65
75
72
 Trough: line of relatively low values
 (Isolines point to higher values)
 Ridge: line of relatively high values
 (Isolines point toward lower values)
 Terms usually used on pressure maps
 Gradient
 Steep/strong gradient: close isolines
 Weak gradient: widely spaced isolines
500 miles
1004
1020
1006
1008
1010
1018
1014
1016
1012
Exercise
Create an isobar map from Station
Models (station model map of US Plains
states)
 Use a 5 mb interval, starting at 1000.
Identify the pressure on each station model. Remember to:
 A) insert the decimal to give the number a tenths place
 B) add a 9 if the first number is greater than 5 or a 10 if the first
number is less than 5.
examples:
184 = 1018.4 mb;
997 = 999.7 mb