VOCABULARY: globe, map; oblate ellipsoid, N, NNE, NE, ENE, E, ESE, SE, SSE, S, SSW, SW, WSW, W, WNW, NW, NNW, grid system, degree, minute, second, latitude, longitude, parallel, equator, North Pole, South Pole, meridian, prime meridian, international date line, cartography, projection, equivalence, conformality, tangency, cylindrical projection, Mercator projection, conical projection, azimuthal projection, planar projection, map essentials, scale, verbal, graphic, representative fraction (RF) or fractional, small scale, large scale, legend, choropleth map, isopleth or isarithmic map, isopleth interval, topographic map, contour line, contour interval, USGS, model, remote sensing, aerial photograph, stereoscopic pair, GIS, mental map
compass directions: words and numbers--See The Compass Rose and Azimuths
grid system--set of intersecting lines
Summary of latitude and longitude: A circle contains 360 degrees (°). A degree is divided into 60 minutes ('), and a minute is divided into 60 seconds ("). Latitude measures the number of degrees north or south of the equator which has a latitude of 0°. The highest latitude possible is 90°. All latitudes except for the equator must be designated either north or south of the equator. Except for exactly at the poles, a latitude coordinate designates a parallel around the earth. The longitude coordinate is also needed then to designate one particular point on the earth's surface. Longitude measures the number of degrees east or west of the prime meridian which runs through Greenwich, England. The prime meridian has a longitude of 0°. Halfway around the globe is the 180° meridian which is the highest longitude possible. All other longitudes must be designated either east or west of the prime meridian. All meridians merge at the poles so exactly at the poles no longitude can be given; the longitude of the poles is left blank. It is required that latitude be given before longitude.
PRACTICE EXERCISE on latitude and longitude map from class--View the map and the answers.
360 degrees in a circle; 24 hours
in a day; = 15 degrees per hour for size of a time zone
central meridians are multiples of 15
cartography--the science of map
need to use a projection--means of representing a curved surface on a flat sheet
characteristics of projections
scale--reduction--shows size relationship
legend--key to the symbols used on the map
direction--orients the map; north need not be at the top of the map
two types of maps: choropleth
choropleth map--used for discrete data; observations may be counted or distinct phenomena located--generalizes and simplifies basic data by assigning different shades of color, representing particular ranges in value, to each subdivision of the map region to result in a general picture of the distribution.
1) form a grid or use a previously formed division pattern
2) record the number of observations in each division
3) set a ranking and color each to show similarities
isopleth map--shows a continuous
distribution as a third dimension
isopleth--line connecting points of equal value
isopleth interval--difference in value between two adjacent isopleths
isopleths shown on the map are always MULTIPLES of the interval
isopleths NEVER cross or divide
isopleths always form enclosed circles (may not be on map)
To determine the value of a point
consider: What is the value of the isopleth interval? Is the point on an
isopleth? (Yes, what value?) (No, what are the values of the two isopleths
it is between? Give all of the possible values.)
View the isopleth transparency question page.
topographic map--shows the relief
(elevation) of the earth's surface using isopleth lines of elevation--contour
also shows other physical and cultural features
United States Geological Survey--USGS--produces many of the U.S.
models--idealized representations of the real world built in order to demonstrate certain of its properties
remote sensing--collection of environmental information from a distance
aerial photograph, stereoscopic pairs
Geographic Information System (GIS)