Mapping Cont.

Cartography Cartography is the science of map making Early maps were usually limited to a very small area and had very little detail compared to modern maps Limited technology Limited understanding of the earth Humans had no need/use for maps beyond their particular local area

Technology Technological advances have dramatically changed cartography Surveying equipment Surveyors use geometry and trigonometry to calculate and accurately map small areas

Remote Sensing Use of satellites to measure and map the Earth Landsat Satellite First launched in 1972 Landsat 7 was launched in 1999 Passive system Receives reflected wavelengths of energy emitted by Earth’s surface ¼ of the Earth’s landmasses are mapped every 16 days

Topex/Poseidon Satellite Topex = Topography experiment Launched in 1992, stopped in 2005 The first satellite dedicated solely to the study of the oceans Active system Uses radar to map changes

Jason series The follow up to Topex/Poseidon Jason – 1 launched in 2001 Jason – 2 launched in 2008 Accurate to 3.3 cm

Sound Navigation and Ranging SONAR SOund Navigation And Ranging Used to measure and map the seafloor Produce bathymetry charts Study of underwater depth of lake or ocean floors

Global Positioning Systems (GPS) First developed in 1960 by the mighty US Navy 5-satellite system that could provide a fix once per hour 1983 President Reagan removed restrictions making GPS available to the public for free By 1994, 24 satellites were in use Receiver calculates the user’s precise latitude and longitude by processing signals emitted by multiple satellites

GPS cont. In 2004 all restrictions were removed, greatly improving accuracy for public use We now have 32 operational GPS satellites providing positioning, navigation, and timing information

Types of Maps Maps are flat models of a 3-D object Any map of the Earth is going to have some distortion because a map is a flat representation of a curved surface. Map projection made by transferring points and lines on a globe’s surface onto a sheet of paper

Conic Projection Map is projected onto a cone. The cone touches the glove along a single line of latitude. Good for mapping small areas, but the area around the poles is distorted.

Gnomonic Projection Map is projected onto a flat piece of paper. The paper touches the globe at a single point. Good for plotting long distance trips, but the direction and distance between land masses is distorted.

Gnomonic Projection

Mercator Projection This map shows lines of latitude and longitudes as straight, parallel lines Good for navigation, but the landmasses near the poles are distorted Example – Greenland appears much bigger than Australia, but just the opposite is true.

Mercator Projection

Topographic Maps Topo maps show change in elevation (height above sea level) Contour lines (concentric circles) connect points of equal elevation Contour lines never intersect or cross Contour lines never dead end Contour lines never fork or split

Contour Lines Contour lines can be more than just elevation Temperature Precipitation Snow cover is frequently shown as a contour-line map Air Moisture Wind Magnetism

Index Contours Index contours have their elevations written on them Contour interval is the difference in elevation between one contour line and the next one.

Contour Lines cont. Contour lines spread far apart indicate a gentle slope Contour lines spaced very closely together represent a steep slope

Depression Contours Depression contours show a decrease in elevation

Map Legends Topographic maps and most other maps include both human-made and natural features located on Earth’s surface Represented by symbols Black dotted lines for trails Solid red lines for highways Small black squares and rectangles for buildings Map legend explains what the symbols represent

Map Scales Ratio between distances on a map and actual distances on the surface of Earth 3 types of scales Verbal Scales – expresses distance as a statement Ex. One centimeter is equal to one kilometer Graphic Scales – consists of a line that represents a certain distance. Line is broken down into sections with each section representing a distance on Earth’s surface. Fractional Scale – expresses distance as a ratio such as 1:63500 Meaning that one unit on the map represents 63,500 units on Earth’s surface