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Types of MapsMercator ProjectionsConic ProjectionsGnomonic ProjectionsTopographic Maps
Mercator ProjectionsMercator Projection
Is a map that has parallel lines of longitude and latitudeFlaws
Land Near Poles is exaggerated Shapes are correct, but land area is distorted
Conic ProjectionsConic Projection
Is made by projecting points and lines from globe onto a cone.Very Little Distortion, High Degree of accuracyBest for Mapping Small AreasUsed to make road and weather maps
Gnomonic Projections
Gnomonic Projectionsis made by projecting points and lines from a globe onto a piece of paper that touches the globe at a single pointDistort Directions and DistanceUsed For Plotting great Circle Routes (Airplanes)
Topographic MapsTopographic Maps
Detailed maps that show the hills and valleys of an areaUse Lines, Symbols, and Colors to represent change in elevation
Map FeaturesMap LegendsMap Scales
Map LegendsInclude symbols for both man made and natural featuresSpecific Colors for Habitats
Green for WoodsBlue for Water
See Appendix D on p. 914
Map ScalesRatio of distance on a map to actual distances on the map3 Types
Verbal: “one inch equals one mile”Graphic: consists of a line that represents a certain distance on EarthFractional: one unit on map represents one unit on Earth
Large Ratio: map covering large area (minor detail) Small Ratio: map covering little are (major detail)
IsolinesAn 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 Isolines:
1. Isolines connect points of equal value.
15
5 5
1510
1010
10
2. Isolines are gentle, curving lines- no sharp corners.
15
5 5
1510
1010
10
3. Isolines are always closed curves even though the map might only show part of it.
4. Isolines NEVER cross- this would mean that one point has two different values. Ex: one spot has two temperatures?
20°
30 °
40 ° 50 ° 60 °
X
YZ
5. Isolines usually are parallel. (They have a parallel trend.)
Visualizations of contour lineshttp://geology.asu.edu/~sreynolds/topo_gallery/topo_gallery.htm
GradientGradient shows how quickly the value changes from one point to another.
Gradientvalue
dis c e
tan
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
Making Contours worksheetsWorksheets can be printed from:http://www.rcmurphy.net/Medina%202005/documents/Contours123.doc
Highlight data points.
Fill in gaps in data.
Connect the dots.
Go on to the next value.
Making a Contour Map II
Drawing Contour Maps III