Unit 3: Mapping Earth's Surface Flashcards
What is the difference between latitude and longitude?
Latitude is the angular distance, measured in NORTH and SOUTH, of a point along a parallel from the equator. Longitude is the angular distance, measured in EAST or WEST, of a point along a meridian from the prime meridian.
What are the reference lines/points for each measurement system?
Equator (latitude) and Prime Meridian (longitude) and Vertical Datum (elevation).
How do properties of scale, area, and shape relate to map projection?
Maps attempt to show 4 components of the earth with perfect accuracy. A map is designed to fit specific needs. All maps have some of these properties, some may be better than others.
What are the differences between cylindrical, conical, and planar map projections?
Cylinder: farther you move away from the equator, the less accurate. Also called MERCATOR MAP. Regions away from equator get magnified.
Cone: Cone touches earth along parallel latitude or meridian of longitude. Everywhere along the latitude will be accurate. Cannot see entire Earth.
Plane: Projects image of earth on flat surface. Causes distortions; not good for large areas. Good navigation chart.
What is an equal-area projection?
The relative area of objects is preserved and we will not be misled about their relative size on Earth. We can compare sizes of objects.
How does GPS work?
GPS satellites transmit signals to a receiver that indicates its location and current time. The signals move at the speed of light. When the receiver estimates the distance to at least 4 satellites, it can calculate its position in 3 dimensions. There are at least 24 satellites at all times.
What are distinguishing features of GIS and remote-sensing techniques?
GIS allows us to map data within the framework of any map projection and to move easily from one project to another. It also allows manipulation of data in novel ways. Remote-sensing technology lets us capture info about objects without the sensor being in direct contact with the object or scene itself.
What is triangulation?
Triangulation measures the distance from 3 different satellites.
What is an isoline/isarithmic map?
Consists of numerous lines that connect all places possessing the same value of a given phenomenon or “height” above the flat base of the surface.
What are active systems?
They emit energy that gets reflected back up to the system (example: radar).
A map projection that retains the correct shape of features is called:
conformal
Which map projection is capable of displaying the greatest amount of the Earth’s surface?
the cylindrical map projection
