Chapter 2: Portraying Earth McKnight’s Physical Geography: A Landscape Appreciation,

© 2011 Pearson Education, Inc. Portraying Earth The Nature of Maps Map Scale Map Essentials The Role of Globes Map Projections Families of Map Projections Isolines © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Portraying Earth GPS—Global Positioning System Remote Sensing GIS—Geographic Information Systems Tools of the Geographer © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. The Nature of Maps 2-dimensional representation of Earth’s surface Show 4 key properties of a region Size Shape Distance Direction Maps are imperfect, since Earth is a sphere Figure 2-2b © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Map Scale Maps are always smaller than the area they represent Map scales are necessary to understand realistic distances on map Scale is relationship between area on map and area on Earth Three primary types Graphic Fractional Verbal Figure 2-3 © 2011 Pearson Education, Inc.

Map Scale Large versus small map scales

© 2011 Pearson Education, Inc. Map Essentials Need several properties of maps to help with interpretation: Title Date Legend Scale Direction Location Data Source Map Projection Figure 2-5 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. The Role of Globes Advantages of Globes Maintains correct geographic relationships between points Can accurately represent spatial relationships between points on Earth Disadvantages of Globes Only can see a hemisphere at a time Large and bulky Cannot contain much detail Figure 2-6 © 2011 Pearson Education, Inc.

Globe properties Parallels of latitude Meridians of longitude parallel to each other decrease in length closer to the poles Meridians of longitude converge at the poles equal length (1/2 equator) Both: intersect at right angles

Map Projections Process of transferring the spherical earth onto a 2-dimensional surface. Estimate size and shape of earth in 3 dimensions Properties of map projections: equal area (area) conformal (shape) equidistant (distance) azimuthal (direction) Types of map projections: cylindrical conic azimuthal (planar)

© 2011 Pearson Education, Inc. Map Projections Equivalence versus conformality dilemma Figure 2-10 © 2011 Pearson Education, Inc.

Families of Map Projections Cylindrical Projections “Wrap” the globe in a cylinder of paper Paper tangent to Earth at equator Conformal projection Mercator projection is most famous Figure 2-7 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc.

Map Projections

Mercator projection

Transverse Mercator

Families of Map Projections Plane Projections Project globe onto a paper that is tangent to globe at some point Displays one hemisphere well Equivalent projection An example is an orthographic plane projection (Figure 2-13) Figure 2-9 © 2011 Pearson Education, Inc.

Families of Map Projections Conic Projections Project the map onto a cone tangent to or intersecting the globe Principal parallel Good for mapping small areas on Earth Impractical for global mapping Figure 2-8 © 2011 Pearson Education, Inc.

Families of Map Projections Pseudocylindrical Projections A mix of conformal and equivalent Central parallel and meridian cross at right angles Oval shaped; distortion increases as you move away from the center Figure 2-11 © 2011 Pearson Education, Inc.

Families of Map Projections Interrupted Projections Minimize distortion Discontinuous map, shapes and sizes maintained Typically oceans are distorted; land masses maintain original shape and size Goode’s projection Figure 2-14 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Isolines Definition Many types Isobar: line of constant pressure Isotherm: line of constant temperature Isohyet: line of constant rain Isoamplitude: line of constant wave amplitude Construction steps/rules Figure 2-16 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Isolines 800 600 500 700 400 300 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Isolines Topographic Maps Show elevation contours Contour lines Lines closer together represent steeper terrain Often used in geography Figure 2-15 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Isolines Topographic Maps Show elevation contours Lines closer together represent steeper terrain Often used in geography Figure 2-15 © 2011 Pearson Education, Inc.

GPS—Global Positioning System Global navigation satellite system for determining location on Earth’s surface Wide Area Augmentation System (WAAS) Continuously Operating GPS Reference Stations (CORS) Figure 2-19 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Imagine you are somewhere in the United States and you are TOTALLY lost -- for whatever reason, you have absolutely no clue where you are. You find a friendly local and ask, "Where am I?" He says, "You are 625 miles from Boise, Idaho." This is a nice, hard fact, but it is not particularly useful by itself. You could be anywhere on a circle around Boise that has a radius of 625 miles, like this: © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. You ask somebody else where you are, and she says, "You are 690 miles from Minneapolis, Minnesota." Now you're getting somewhere. If you combine this information with the Boise information, you have two circles that intersect. You now know that you must be at one of these two intersection points, if you are 625 miles from Boise and 690 miles from Minneapolis. © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. If a third person tells you that you are 615 miles from Tucson, Arizona, you can eliminate one of the possibilities, because the third circle will only intersect with one of these points. You now know exactly where you are -- Denver, Colorado. This same concept works in three-dimensional space, as well, but you're dealing with spheres instead of circles. © 2011 Pearson Education, Inc.

Remote Sensing Measurement by a device not in contact with Earth’s surface Common types include: Aerial Photographs Orthophoto maps Visible Light and Infrared (IR) Scanning Thermal IR scanning Radar and Sonar Many others Aerial Photography—Figure 2-20 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Remote Sensing Orthophoto maps Photographic maps that are multicolored and distortion free Useful in low-lying coastal regions to show marsh topography Figure 2-21 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Remote Sensing Visible light and IR scanning Based off of visible light and IR part of electromagnetic spectrum (Figure 2-22) Shows “false color” Figure 2-23 Figure 2-22 © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Remote Sensing Radar Imagery “Radio Detection and Ranging” Useful for identifying atmospheric moisture Sonar Imagery “Sound Navigation and Ranging” Permits underwater imaging Thermal IR scanning Scans in the thermal IR part of spectrum Shows images based on temperature Often utilized in meteorology © 2011 Pearson Education, Inc.

GIS—Geographic Information Systems Computer systems used to analyze and display spatial data Layers of data used in mapping Requires high powered computing to process multiple maps Figure 2-29 © 2011 Pearson Education, Inc.

Tools of the Geographer Vast array of maps, remotely sensed satellite imagery, and computer applications Difficult to determine the best way to use all of this information Some tools better at identifying features on Earth than others Ultimate goal: “To better understand Earth.” © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Summary Maps are essential to portray features on Earth’s surface Need a map scale to identify how a map relates to the actual surface features on Earth Many other map properties are essential to interpreting a map Globes have several advantages and disadvantages Representing Earth in 2 dimensions can be done through map projections © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Summary Many different map projections exist Dilemma of equivalent versus conformal Plotting isolines on a map can help with interpretation of features on the map The global positioning system (GPS) helps to identify location on Earth’s surface Remote sensing is a measurement of Earth’s surface from a system not on Earth’s surface © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc. Summary Many different remote sensing instruments exist, including satellite, radar, and sonar GIS are computer systems used to analyze and display spatial data, often in layers The geographer has many tools, but the ultimate goal is “To better understand Earth.” © 2011 Pearson Education, Inc.