GEOGRAPHY 101 Front PageREPRESENTATION OF EARTH
MATERIALS NEEDED FOR CLASS:
Daily Lesson Plans. H.K.C--Take roll and announcements. TEXT: Essential of Physical Geography: Third Edition, Robert E. Gabler, Robert J. Sager, Daniel L. Wise, and James Peterson. Saunders College Publishing, Harcourt Brace College Publishers 1999. Rand McNally GOODE's WORLD ATLASGENERAL OUTLINE
II. Representations of Earth
A. To discuss the importance of location and the means of finding
location.
B. To delineate, the role of Globes and to compare and contrast great
circles,small circles and great circle routes.
C. To recall the size and Shape of the Earth, the Geographic Grid,
Latitude, and Longitude.
D. To tell time, and know the difference between standard time,
daylight time, and the international system for telling time.
E. To recall the Public Lands Survey System, the Township and Range System.
F. To explain the Global Positioning System and the system of triangulation.
G. To discuss Maps and to portray Map Projections.
H. To examine the essentials of maps and define scale, direction,
I. To identify the different kinds of Maps.
J. To recognize Modern Mapping Technology--Computer Mapping or
Automated Cartography, Geographic Information Systems,
Remote Sensing Systems--Photographic and Non photographic
systems.
THE MATERIAL IN THIS OUTLINE COVERS PAGES 31 to 69 BUT THERE IS MATERIAL NOT IN YOUR BOOK--KNOW IT--KNOW IT--KNOW IT
ANTICIPATORY SET How do you find locations on Earth? What is the Public Lands Survey System? How is a Globe different than Maps? What is the Global Positioning System ? How does Latitude and Longitude differ? What are Map Projections and what are the problems involved in projections? How is the Geographic Grid used? What are Map Essentials? How do you tell Time? (This is not a joke question it is not as simple as it sounds, but it not as hard as it could be) Are there different kinds of Maps? What are the new Modern Mapping Technologies? What is Remote Sensing?
BEHAVIORAL OBJECTIVES
To define navigation. To identify the Township-and Range system. To compare and contrast true north and magnetic. To identify Cartography. To define principal meridians, base lines, township, range, and sections. To describe the different kinds of maps. To compare and contrast the great circle and small circles To portray the Global Positioning System. Know your lines there are more than just the ones below the key term is ISO To stress the spatial concept and locate places using latitude and longitude To define maps. To recognize Isolines, Isotherms Isobars, and Isohyets. To delineate the imaginary lines of the North and South Poles, and the Equator The next five points are closely tied so keep that in mind To depict Topographic Maps and identify Contour Lines. To recall the use of the Sextant. To portray the different types of Properties of Map Projections. To describe Computer Mapping Automated Cartography. To illustrate the Geographic Grid. To relate Equivalence in Map Projection To recount Geographic Information Systems. To recall Solar Noon. To identify Conformal maps To sketch the history of Aerial Photographs and to Contrast Orthophoto Maps To recount the American and Canadian railroad agreement and the International Meridian Conference To describe the Mercator Projection To contrast Color and Color Infrared Sensing To point out why the Prime Meridian runs through London (Greenwich) To identify Conic Projections and the Lambert conformal conic projection. To remember many developments in Geographic Information occurred because of military needs. To learn how to tell time, no kidding what do I really mean? MAP ESSENTIALS To identify Thermal Infrared Sensing , Microwave, Sensing, Radar To define Universal Time To recall Title Date, and Legend and Sonar Sensing, Multispectral Remote Coordinated and the old Greenwich Mean Time, Zulu time To relate the Scale types Sensing, Multispectral Remote Sensing, and Landsat Sensor Systems. To discuss the International
Date LineINSTRUCTIONAL INPUT
Content Methods:Lecture andClassroomdiscussionI LOCATION ON EARTH
A. Direction is the second universal spatial concept I want you to know. Like location it has both absolute and relative definitions. Absolute Direction is simply the cardinal points of the compass, north, south, east, and west. The cardinal points appear in all cultures. East and West reflect the rising and the setting of the Sun, while North and South refer to the position of fixed stars in the night time sky. The priests scanned the skies to predict the future--the beginnings of astrology, astronomy, and map making. Knowledge of the stars and the sun, and their relationships are part of the science of navigation or as expressed by your book getting from where you are to where you want to go.(What is the fixed star in the Northern Hemisphere?)
B. Some early civilizations thought the Earth had the shape of a flat disk. If you look over the plains of Mesopotamia, this is not an unreasonable assumption. Driving through Kansas you might get the same assumption today as well. The oldest surviving map of the world is a clay tablet from Mesopotamia it is about 2,500 years old. There are, of course, older maps, which have not survived. (See Figure 2.1 on p. 32.) The ancient Egyptians also developed a very good system of geometry for the measurement of land--mapping the land. They also had maps and guidebooks to the afterlife. (Why did the ancient Egyptians have to develop geometry to map their lands. What has changed in Egypt in the last 5,000 years?)
CARTOGRAPHY
C. The people who make maps are called cartographers and their art and science is called cartography. It is a blend of both art and science because not only do maps have a scientific basics they can be very beautiful as well. They are more than just pieces of paper on what road to take. They can delineated almost anything and are a major tool for geographers. (I'll talk more about maps and the new technology of computer map making in another section so pay attention.).
D. Maps can identify regions and give those regions meaning. They can pin-point a place within just a few feet, they can describe spatial distribution, and can measure distance. They can also interpret the invisible, like what area a language or religion is dominant. A map is also a time machine. It can display past events, political borders of long past civilizations, and describe things at the dawn of time. They can show the interactions between peoples and the physical world. Sometimes you can even fold them back to their original shape and put them back into the glove compartment of your car. (Just in case you don't get it, the last sentence was a joke.)
II GLOBES AND GREAT CIRCLES
THE ROLE OF GLOBES AND THE LIMITATIONS OF GLOBES
A. To best display the true sphericity of the Earth nothing can beat a globe--A perfect model. A globe can show the true geometric relationships of meridian to parallel. The spatial percentages are true for landforms and bodies of water. It can display comparative distances between places, relative sizes and shapes on the planet. A person can view the entire planet instead of merely visualizing it. The course of the seasons can be traced and the length of a day in different places can be observered. (Take a look at Figure 2.2 and compare a globe and the photograph)
B. There are some problems, even with a globe. One problem with a globe is scale, the big picture is fine but details are lost. Only half of a globe can be viewed at one time, many times it is the polar regions which are hard to see. Another problem is portability although you would not have to worry about folding them up, they would not fit the in glove compartment of your car, and if they could, they would be too small to be of any use. Maps are more versatile but they can have problems as well. (I'll talk more about the problems of maps in another section.)
GREAT CIRCLES AND GREAT CIRCLE ROUTES
(Note: This is a little out of order from your text, but I think it more sense to connect both Great Circles and Great Circle routes together.)
C. When a sphere like the Earth is cut into two equal halves passing through the center, it is called a great circle. In the case of the Earth it is only an imaginary plane cutting through the center of the Earth. It is called a "great" circle because it is the largest circle which can be made around the Earth. An infinite number of great circles can be drawn on the Earth, the lines of longitude and the equator are great circles. (Take a look at Figure 2.3 on p. 34)
USEFUL CHARACTERISTICS OF GREAT CIRCLES
1. Every great circle divides Earth into equal halves called hemispheres.
2. Every great circle is a circumference of Earth.
3. Great Circles mark the shortest travel distance between places on Earth.D. Another great circle can be made by connecting two points on the surface of the Earth, these are the great circle routes. These routes are used by ships and air planes, and are like cutting corners, after all the Earth is a sphere, and are always the shortest route between two places. (If you want to get technical, it is the arc of the great circle which is the shortest point between two places.) Perhaps a good example is an airplane going directly from Los Angeles to London instead of flying to New York and then across the Atlantic. The plane cuts across Northern Canada and skirts over southern Greenland, this saves time and more important money. One example of a great circle, or hemisphere is the Sun illuminating half of the Earth called the circle of illumination--half of the Earth is in daylight the other half is night.
SMALL CIRCLES
E. Planes which do not cut through the center of the Earth are called small circles. The only parallel which is a great circle is the equator, all others are small circles. (Take a look at Figure 2.3 c for an example of small circles.)
III LATITUDE AND LONGITUDE
A. Geography is like Real Estate, finding the right location. Your book uses the example of a road map to find Canton, Ohio. You can find a similar system for a street location in most phone books. There are even some atlas which use the same system. Your atlas does not. Perhaps the best system is something like the Cartesian coordinate system. What is needed is a grid system or grid cell with two intersecting lines. Some lines run East--West while others run North--South. It is a little more difficult to do on a sphere without reference points.
B. Since the Earth rotates on an imaginary axis a North South imaginary line runs from the North Pole to the South Pole, which serves the two reference points for the planet. Half way between the two is the the equator, which can form a great circle. By using a North South axis and the equator any point on the Earth can be pinpointed in a North South direction called latitude.
LATITUDES RUN EAST TO WEST
C. Latitude is the angular distance north and south of the equator. Since the world is divided into a circle of 360š. A location, a place on the map or globe, is measured in degrees, minutes, and seconds. Latitude at the equator is 0š. Any location north of the equator is North Latitude, while any location south of the equator is South Latitude. Your text uses the example of Los Angeles, but any city or place could work.
D. A device used to determine latitude for celestial navigation is the sextant. (Take a look at Figure 2.6 on p. 36.) The sextant measures the angle between the horizon and the noon day sun, the North Star, or some other celestial body.(Is that enough to find a place on the Earth or is something missing?)
LONGITUDE RUN NORTH TO SOUTH
Note: Longitude, the Prime Meridian, and Time Zones are linked and when you talk about one you imply the other, following the structure of you're textbook. I do not want to confuse people, this material can be difficult.
PRIME MERIDIAN
E. Just like Latitude a reference point is needed for east to west measurements.The equator, of course, was a natural division, but no such line existed for an east west line. Such a line would be called the
prime meridian. It was a point of national pride for a country to have the prime meridian pass through their capital.There were as many as 13 different "prime meridians" in use before the 1880s. The problem was eventually settled in 1884 by the International Meridian Conference attended by 27 nations in Washington D.C. Despite several weeks, more for show than anything else, it was decided that the Royal Observatory at Greenwich, England, a suburb of London, would be the "prime meridian" or 0š longitude. Considering that about 70 percent of the world's shipping was British and American and they already used Greenwich as the prime meridian, and the Royal Navy was the largest in the world, choosing Greenwich was almost a slam dunk.F. Longitude is similar to Latitude. It is the angular distance east or west of the prime meridian 0š longitude. It is measured in degrees, minutes, and seconds, but is calculated from east to west. They are not parallel to each other except at the equator. At the poles they meet each other and are great semicircles. Depending on the direction a person travels, east or west, from the prime meridian or 0š longitude, longitude increases. Eastward from the prime meridian halfway around the planet the meridian becomes 180š E Longitude and is also 180š W Longitude.
THE GEOGRAPHIC GRID--PARALLELS AND MERIDIANS
Note: Sometimes even my best students get a little confused about latitudes, longitudes, parallels, and meridians. The way a line runs is its direction but divides the earth in the opposite way. (Take a look at Figure 2.7 on p. 37.)
G. Any spot on the planet can be plotted using latitude, (north and south), and longitude, (east and west), by using the Geographic or Global Grid.The Geographic Grid has also been extended to moon and other planetary bodies. Latitude lines run east to west and connect all points along the same latitude and mark latitudes north and south of the equator. These lines are known as parallels, the only parallel which is a great circle is the equator, while all others are small circles. One degree of latitude equals about about 69 miles at the equator. Lines of longitude run north and south meeting at the poles and measure distances east or west.
SUMMARY: Latitude measures angular distance north and south of the equator 0š and run due east and west. Parallels are the lines connecting the same latitude.
Longitude is the angular distance east or west of the prime meridian and are drawn north and south. Each meridian of longitude when connected with opposite number forms a great circle. Meridians at any given latitude are evenly spaced around the globe, but the distances between them decreases as they move poleward. Meridians are the names of the lines.
IV LONGITUDE AND TIME
A. It is not difficult to tell time by looking at the angle of the Sun. Each city set their own time by fixing their local time by solar noon. Solar noon is the time of day when the sun reaches its highest position in the sky. There were no major problems, after all a person was limited by the speed of a horse or his own legs. Even after the development of mechanical clocks in the late Middle Ages there were still no major problems for most people.
INTERNATIONAL PRIME MERIDIAN CONFERENCE
B. The issue of time became a problem in the late 19th century in America with the transcontinental railroad system and the telegraph. Each city had its own time, just imagine the problems if Pueblo, Colorado Springs, and Denver had different times. As late as 1870 a train passenger had to make 22 changes to stay with local times. The railroads were the first to set standardized time zones for the United States and Canada in 1883. This concept was extended in 1884 with the International Prime Meridian Conference in Washington.
TIME ZONES
C. Part of this agreement was to set 24 standard time zones for the entire world. Each extending over 15š of longitude, (360š divided by 24 hours.) The Prime Meridian was placed at Greenwich England. Greenwich became the time standard for the entire world. All that is needed to tell time anywhere in the world is to know how many hours the local time is ahead or behind Greenwich. Sometimes for political and economic reasons the time zones in the United States do not correlate to meridian time--time zones. (Take a look at Figure 2.8 on p.38 and pay attention to the cutline. By the way how many hours difference between Denver and Greenwich?)
GREENWICH MEAN TIME (GMT)
UNIVERSAL TIME COORDINATED (UTC) AND ZULUD. The global time line is still at Greenwich but there is a little confusion over names. Some people refer to the time at the prime meridian as Greenwich Mean Time, GMT. However, in 1972 the named was changed from to Universal Time Coordinated UTC. The American military refers to it as Zulu time. Meaning zero time or where time begins. They are the same thing just different names.
E. Time zones west of the prime meridian are on slow time while those east are on fast time. Ships, airplanes, and some locations have two chronometers, very accurate clocks, one set on Greenwich time, while the other is set on the local time. The number of hours difference, fast or slow, establishes longitude.
SOME CLOCKS KEEP BETTER TIME THAN THE PLANET
F. Time has gotten so critical for computers, telecommunications, and other scientific applications that even leap seconds are added from time to time because of the irregular rate of rotation of the Earth. Six special clocks keep time for the entire planet. These clocks keep better time than the planet. The clock uses the very regular vibrations of cesium atoms to keep time. The sixth clock of this type began to keep time in 1994. (What city in Colorado is this time piece kept?)
THE INTERNATIONAL DATE LINE
G. One advantage of using Greenwich as the prime meridian is on the other side of the world, it becomes the 180th meridian. The 180th meridian runs through the vast Pacific and again for political reasons it does meander a little but not as much as in North America. If a person is traveling west across the International Date Line he must Turn the calendar ahead one day. The first time man encountered the International Dateline was on Magellan's voyage around the world. What was left of his expedition found their calendar was a day off. They had traveled west to east. (Take a look a Figure 2.9 on p. 39 and read the cutline.)
V PUBLIC LANDS SURVEY SYSTEM
A. Geographers like to define things and delineate them on maps. It is their job and they like to use the Geographic Grid. The prime example of this is the U.S. Public Lands Survey System or the Township-and Range System. To make matters more confusing in American History it is usually refers to as the Land Ordinance of 1785. Just different names for the same thing. The idea of survey came from the mind of Thomas Jefferson for selling public lands. The American Government was broke, it had just won the Revolution, but had very little money. (Why was the land called Northwest Territory?)
B. It first applied to the area beyond the Appalachians--The area lying north of the Ohio River and east of the Mississippi River (Take a look in the Atlas on pp. 96-7 and tell me what states are in this area?) It was later used for almost all the land in the American West. The land was surveyed into tracts using north-south lines called principal meridians and east-west lines called base lines. The north-south lines (meridian lines) had to be modified or shifted from time to time because of the spherical nature of the planet and northern tracts would have been smaller than southern tracts. (Remember meridian lines converge pilloried.) The baselines using parallels of latitude did not have the same problem.
TOWNSHIP AND RANGE LOCATIONS
C. The Township and Range System shapes the land into a very distinctive pattern of almost perfect square tracts called townships. Townships are arranged in horizontal tiers north and south of the baselines and in vertical columns ranging east and west of the principal meridians. The land was divided into squares 6 miles by 6 miles to form a township. A location within a township is also defined by the range which is its location east or west of the principal meridian. Like many things in this course, a diagram can be better than words. (So take a hard look at Figure 2.11 on p. 40 at least two of the diagrams are very important.)
D. The township was further subdivided into thirty-six sections of 640 acres each or one square mile. Each section has a number, one through thirty-six, beginning in the northeast most section and ending in the southeast corner. Each section was quartered into tracts of 160 acres. (How large is an acre and what is the significance of 160 acres in American History?)
A WELL DRAWN BOUNDARY AND PATTERN
E. The Township and Range Systems carves the land into a well drawn boundary. The impression on the landscape in the American Midwest and West is eye-catching and the checkerboard pattern and is even more visible from the air or space. (Take a look at Figure 2.12 on p. 41 and read the cutline. Can anyone figure out where the photograph was taken?)
VI THE GLOBAL POSITIONING SYSTEM
OVERVIEW: Remember that any location on Earth can be found using the Global or Geographic Grid. There are old technologies which use the Geographic Grid like an Atlas, and many maps, but not all places are in an Atlas or even on maps. There are new technologies which also use the Geographic Grid, one of those technologies is the Global Positioning Systems (GPS.)
A. The system uses a network of 27 satellites in geosynchronous orbit of 11,000 miles above the Earth, (just last year there were only 24 of them.) A geosynchronous orbit is when a satellite matches its speed with the Earth's rotation, thus maintaining a constant relation to points on the Earth. (What natural satellite of Earth is in geosynchronous orbit of Earth?)
B. Sometimes things we use for every day life that make life easier come from the Space Program or as a direct result of military research. These things are called spinoffs and there are examples like Velcro, from the space program. The Global Positioning System, GPS, is another. It is a satellite based system for pin-pointing any location on the Earth. The boys from the Pentagon devised this system in the 1970s and 1980s to guide missiles, navigate aircraft and ships, and support infantry. (Can someone give a recent example for the use of this technology in action and what type of weapons systems was used?)
FACTORS IN ACCURACY
C. The Global Positioning System uses the very old system of triangulation, known distances, called baselines and known angles with a modern twist. (You can read in your about how it is done with the GPS.) The same basic principles have been done for centuries in surveying land, navigation, and by artillery gunners to hit their targets.) There are several factors which determine a unit's accuracy. A minimum of three satellites is needed but more satellites enhance accuracy. (Take a look at Figures 2.13 and 2.14 on p. 42 )
D. Usually a group of four or more is in constant radio communication with each other and a receiver, assuming it is turned on. Since four or more satellites are used, it is possible to get three-dimension coordinates from the receiver. Besides the number of other satellites, terrain and vegetation can get in the way of radio waves. Another factor is cost, some commercial units cost less than $100. I do not know how much military units cost, you can be the judge. Non-military accuracy for the GPS system can be within 330 feet, military accuracy can hit a target within 30 feet. Just hope you are not in a target location. (This was the best public information as of last year but things might have changed.) This system was first the size of file cabinet, but now they can fit in the palm of your hand. Using the best GPS system and level terrain they can be more precise than the best maps.
USES FOR GPS
E. President Reagan opened the system free to the public in 1983, not counting the cost of the unit. Almost anything that moves is a potential customer. As of last year GPS has been use in earthwake prediction, ocean floor mapping, volcano monitoring, surveying, and there are models for hikers. Some high priced automobiles all ready have them perhaps you might have seen their ads. The GPS system has a very new use the tracking of 60 paroled sex offenders according to the Denver Post, August 28, 1999. They will be fitted with an ankle bracelet and battery pack to keep track of their movements. Perhaps parents in the future could use a small GPS to keep track of teenagers. Private eyes could keep track of husbands with more than one girlfriend.
VII MAPS AND MAP PROJECTIONS
ADVANTAGES OF MAPS:
A. Yes, we finally got to the thing most people think of when they think of geography, but they are more than just pieces of flat paper on what road to take. Some of their advantages are so obvious they might go unnoticed. They can be duplicated in great numbers and very cheaply, at least since the printing press. They can display the whole planet, or define a small area in great detail. Compared to a globe, maps are very portable and you can handle many of them very easily. Maps are more versatile.
B. Perhaps you have noticed some comments I make about looking at a particular figure in the book. Sometimes a graphic can tell you more than the words on a page or the sounds of a lecture. Maps are even better than figures. Read the first paragraph in column one on p. 43 in the text.
C. They can delineated almost anything and are the major tool for geographers. Other textbooks describe maps as the critical tools which geographers describe spatial information and spatial relationships. Your textbook calls a map the geographer's most important tool. I like, A map is not reality but a mirror of reality. Just reread my first description of maps on pages three and four and compare them to your textbook on the first column of p. 43.
VIII LIMITATIONS OF MAPS
A. Maps have a built in distortion, because they are a two-dimensional represention of the Earth. Maps are flat pieces of paper or on a flat computer scene, but the Earth is three-dimensional remember the Earth is a curved surface. A globe does not have distortion, but has its own set of problems. No one type map is an ideal model for all uses
B. Some distortions are greater than other distortions. When a map depicts a small area like the campus the distortions are so small to be insignificant, but when a map tries to display a large area like the Earth, distortions can become significant because of the spherical nature of the planet. Despite problems of distortions, maps can be useful depending on what type of distortions are acceptable in any given map.
C. The optimum projection is always determined by its intended use. Perhaps an analogy with automobiles might help. If you want a four-wheel vehicle a Corvette is not the right choice. To determine what is the right map for a set of needs four factors must be considered. Yes, I know I've talked about some of these things before but they are important, and you might not have made the connection.
1. Lines of latitude are called parallels and are always parallel to each other.
2. Parallels are evenly spaced.
3. Meridians of longitude converge at the poles.
4. Meridians and parallels always cross at right angles.MAP PROJECTION
D. All Map Projections involve some type of compromise. Somewhere along the line, no matter what type of projection is used, distortion creeps into the map. The map no matter how well drawn has distortion.
IX PROPERTIES OF MAP PROJECTIONS
NOTE: The problems dealing with map distortion and map projection pp. 43 to 48 are in the text and I'm trying to tie things together. It would not hurt to pick up your Atlas, that is the book with the maps in it, and read vi to xi and pay special attention to the section on map projection. The more view points on a topic the better you can be in a subject. I use three main texts and several minor texts for these notes and try to pick the best out of each.
THE TWO MAJOR TYPES OF MAPS
CARTOGRAPHERS ARE FACED WITH A DILEMMAA. Cartographers are faced with dilemmas and needs to make a choice, either shape or size. These problems occur in maps that display large areas. A flat map cannot depict large areas of the globe without distortion of either shape called conformality or area called equivalence. Maps that preserve true shape are called conformal. Maps which display the equal areas of space are called equivalence or area projections. In each type of map there are tradeoffs.
EQUIVALENCE--AREA THE CHOICE OF SIZE
B. In an equivalent map all places on the map have the same spatial relationships between each other and to the corresponding area on the ground. In short, they show area correctly and are called equal area maps. When size is the important consideration, this is the map of choice. This type of map is the best map for representing spatial distributions on the planet. The Earth is in proper proportion using this type of map. To illustrate this point, a coin placed on one part of the map will cover the same area on another part of the map. (I have three different texts which use the same analogy the only difference is the type of coin.) An equivalent projection is very good at showing equal areas of space, but has problems showing shapes. Places like Alaska and Greenland seem compressed and New Zealand is more elongated.
CONFORMAL PROJECTION--THE CHOICE OF SHAPE
C. Projections which stress shape are called Conformal projections. The most famous is the Mercator projection. All conformal maps have the meridian and parallels crossing at right angles and are correct in every direction in limited areas. The shapes are correct for the most part, but size is another matter especially in the polar regions. Greenland looks bigger than South America, Africa, and Australia. In fact Africa is 14 times larger, and South America is 9 times larger, and Australia is 3.5 times larger. Alaska also appears far larger than Mexico, but Mexico is far larger. Antarctica, the Ice Continent, looks as large the rest of the world combined. This projection has been used a great deal in American class rooms and has given students a warped view of polar regions. (Take a look at Figure 2-15 on p. 45 and the Figure 2.8 on p.38. I'll talk more about the Mercator project in just a point or two.)
TWO OTHER PROBLEMS IN MAP MAKING
DISTANCE AND DIRECTIOND. Large flat maps not only have a problem with true shape, but distance as well. The scale in one part of the map does not work on other parts of the map. On maps of only a small area this is not a major problem. A map can be drawn which does portray correct distances called an equidistance map, but choices of either parallels or meridians must be chosen.
E. Compass direction is another problem with some flat maps. A map capable of showing true direction is called an Azimuthal map or Zenithal maps. They have a center of focus and provide true compass headings. (Take a look at Figure 2.16 on p. 46.) It does have its limitations because it can only show one hemisphere at a time. (I'll talk more about the azimuthal system in another section.)
X MAP PROJECTIONS
A. A map projection is the method of representing the curved surface of the Earth on a flat surface. All projections, no matter what form they take, must maintain their location as far as their location on the globe. All map projections have one thing in common the correct location of latitude and longitude lines. There are many different types of projections and they are created in different ways.
THE MERCATOR PROJECTION
B. Perhaps the most famous projection is the Mercator projection which is still in common use today. Remember it is a conformal projection.The Mercator projection is named after Gerhardus Mercator, a Flemish cartographer, (modern day Belgium,) who designed it in 1569. It is a cylindrical projection (Take a look at Figure 2.17a on p. 46 and p. ix in your Atlas.) It is still a wonderful projection for navigation, it's designed use. The Mercator projection is the only world projection that has true compass headings. A navigator can plot a "great circle course," and sail from one compass point to another and reach his destination. It can take several connected lines to plot a course. These are called Rhumb lines or Loxdrone lines. (Take a look at Figure 2.15 p. 45. Read the cutline.)
RHUMB LINE OR LOXDRONE LINE
NOTE: Remember trying to show the curved surface of the Earth can lead to distortions. Your eyes may see one thing on a flat map while in reality things might be just a little different.
C. A Rhumb line or Loxdrone line is a curve on the surface of a sphere that crosses all meridians at the the same angle. A navigator plots a course from point to point using rhumb lines allowing the navigator to maintain constant compass headings or bearing over small distances. The line will always be on the mark no matter where they are plotted on the map and is a line of constant direction. (Take a look at Figure 2.15 p. 45 and compare them to Figure 2.18 on p. 47.) The Mercator is not the only projection which can use Rhumb lines for navigation. The Gnomonic Projection also uses Rhumb lines but they look like straight lines, while the Rhumb lines on the Mercator projection appear as curved lines.
CONIC PROJECTIONS
D. Not all projections are designed for blue water sailers but have limited uses. One projection is the Conic projection which is used for small areas in midlatitude locations like the Continental United States. (Take a look at Figure 2.17c on p. 46 to understand the projection and take a look at Figure 12 on p. xi in your Atlas for an example of this type of map.) Maps using this type of projection have minimal distortion. It is an equal area map and uses a standard parallel.
E. The Lambert conformal conic projection is a very practical and precise map. The distortion on this map is only 1 percent from the Canadian line and Mexican Border. It works best for east to west areas in the middle latitudes. It is widely used for aeronautical and meteorological charts and uses two standard parallels. (Take a look at Figure 2.19 on p. 48 of your text and Figure 15 on p. xi in your Atlas.)
XI MAP ESSENTIALS
TITLE, DATE, AND LEGEND--ESSENTIALS
A. As you know, maps come in all shapes and sizes, after all they are more versatile than globes. Every good map should have certain basic elements or essentials. Every good map should have a title , which tells us what is being portrayed. Another important element is the date. Depending on what you are looking for, a very old map could be useful. A map should also have a legend, symbols, colors, shading, or some other device explaining certain features. (Take a look at Figure 2.21 in your text book for standard used by the USGS topographic map symbols.)
THE LEGEND IN YOUR IN THE ATLAS
B. The legend in your Atlas is on p. 60. It would be a very good idea to know the page number. Knowing the size of cities can be very useful. Being able to recognize urban areas and to know the difference between national capitals and secondary capitals as well, political boundaries can also be important.
OTHER IMPORTANT ELEMENTS
C. A map also needs some other elements like Scale, Direction, and Location. Data source can be important because it can be useful to know who is making the map. Projection type can also be helpful.
XII MAP SCALE
A. In order to read a map without pain or worry a person needs to understand scale. Scale is the ratio of the distance between two places on a map and the real distance between those two places on the Earth's surface.Your book has a slightly different definition in the text. It is important in the understanding of maps. All definitions are very close, it depends on what textbook is being used at the time. Scale is determined by the size of the unit measured. Depending on scale the greater or lesser distortion there will be. This is not a problem in maps depicting small areas like states or cities.
WORD OR VERBAL SCALE
B. A Word or Verbal Scale are just words giving the ratio between the map scale and the distance. An example would be "one inch = one mile" or any other unit equaling a certain distance. If the map is reduced or enlarged. Another problem with verbal scales if people do not understand the units being used. Just as an example only a few countries use miles, inches, and feet. Even the American military has switched to metric in the 1960s.
REPRESENTATIVE FRACTIONAL SCALE --RFC. A fractional scale can be a little intimidating at times, again it is a ratio called a representative fraction it is simply the number 1 over a much bigger number an example could be 1/10 or 1:10. Sometimes these numbers can be a little awesome like 1:1,000,000. Any type of unit can be used as long as they are both sides of the ratio.
GRAPHIC SCALE OR BAR SCALE
D. Scale can even be broken down in other ways as well. The first is a graphic scale or bar scale. This might be the scale many people are familiar with. It is very simple, you can measure a line, transfer that distance to the map, and get the approximate distance for two places on the Earth. If you were to blow up the map, or reduce it, the scale would remain the same. Just take a look at the scale below.
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DIFFERENCES IN SCALE
E. Scale will vary depending on the size of the Earth represented on the map. Small scale maps display large areas and information.is more generic. They have large denominators in their representative fractions. Large scale maps delineate small areas and have greater details. At first it may seem contradictory, but large-scale maps show small areas, and small scale maps show large areas. (Take a look at Figures 2.22 on p. 51 for examples of scale.)
XIII DIRECTION AND LOCATION
DIRECTION--DON'T GET LOST--KNOW THE DIFFERENCE BETWEEN
TRUE NORTH AND MAGNETIC NORTHA. The Absolute Direction is simply the cardinal points of the compass, north, south, east, and west. They can be found using the global grid, remember parallels and meridians. On many maps there is an arrow indicating north on the map. The arrow may be either true north or magnetic north. Sometimes there will be two arrows, one for each. Magnetic north is not true north and a compass needle points to magnetic north. If the magnetic declination, the angular difference between the two is given, (Take a look at Figure 2.23 on p. 52), an adjustment in course should be taken. Magnetic declination is different from location to location and is changed from time to time.
B. A map displaying magnetic declination is called an isogonic map. (Take a look at Figure 2.24 on p. 53.) The lines connecting locations with the same magnetic declination are called isogonic lines. The line that connects these points is called the agonic line a line of zero magnetic declination.
LOCATION
C. The Global Grid has been used for maps and globes, but there is another location system called the Azimuth or bearing system. It determines location by a known compass direction. A full circle of 360š is drawn with respect to north. North is either 0š or 360š and is read like a clock. A location is described as so many degrees from north. Due east would have an azimuth of 90š , due south would be 180š. The bearing system divides the circle into four quadrants of 90š (N, E, S, W) each numbered by directions in degrees from north and south. This system is used for exact directional instructions for astronomy, mapping, surveying, navigation, and directing artillery fire.
XVI DIFFERENTIATION AND DISTRIBUTION ON MAPS
HOW MAPS SHOW DATA
A. There are many different kinds of maps, remember maps are more versatile than globes and are a mirror of reality. Some maps which measure a specific spatial distribution of a single category (or few related one) of data are called thematic maps. Maps of this type could display climate, vegetation, soils, or almost anything else. (Take a look at pp.1-59 in your Atlas for the many different kind of thematic maps.)
B. Some maps show patterns and distributions of something across one example is the dot map or point map. A dot, of any given value, is placed to suggest a spatial pattern, distribution, and dispersion. If you noticed certain crime shows, the police stick pins into a map to show where crimes occurs and if there is a pattern. Sometimes other graphic symbols are used instead of dots. Dot maps are most commonly used in maps describing population density and distribution. They are not limited to population. (Take a look at Figure 2.25 on p. 54 What state is it and what city is the north-east corner?)
ISOLINE MAPS
C. Distributions can be made by using a variation of the dot or point map. An isoline map features lines called Isolines that connect dots or points of equal value. An example is the weather map recording the same temperature or some other climatic event. (Take a look at your Atlas p. 12-17 for example of these maps and remember the map of magnetic declination.)
ISOLINES--THE PREFIX ISO IS VERY IMPORTANT
D. Sometimes the key to success is very simple. One such key is the ISO PREFIX. For this class some other forms of Isolines will come into play later in the course, it would be a good idea to know them. Isotherm is a line joining points of equal temperature. Isobar is a line linking points of equal atmospheric pressure. Isobaths also called bathymetric contours, are lines of equal depths of water. Isogonic lines join points of equal magnetic declination. Isohyet is a line joining points of equal amounts of precipitation. There may be some others along the line.
TOPOGRAPHIC MAPS--CONTOUR MAPS
E. Another form of an isoline map is the contour map. A line on a contour map displays identical elevation above sea level (there are some land areas below sea level.) Sometimes these maps are highlighted for added importance. This type of map, depicts land in relief or gives a three-dimensional aspect to terrain. (Take a look at Figure 2.27 on p. 55.) The contour interval is the vertical distance, a constant difference, between two adjacent contour lines. If you can read a contour map other maps using isolines employ many of the same principles. The one principle I want you to know is the closer the contour lines are on the the map, the steeper the gradient. If you were hiking you would not need a map to know the climb was becoming more difficult.
F. Most contour maps display more than just lines, roads, streams, lakes, hiking trails, and rivers are also shown and they are also color coded. This type of map is invaluable to fishermen, hunters, and hikers and are called topographic maps. The U.S. Geological Survey one of the world's largest mapping agencies produces topographic maps and has recently completed a complete mapping of 7.5 minute quadrangles covering of the United States except for Alaska. (Sometime it is a little difficult to order the map you need without knowing the quadrangle.)
XVII MODERN MAPPING TECHNOLOGY
AUTOMATED CARTOGRAPHY
A. For thousands of years cartography was simply drawing lines and sometimes painting images on maps. However, in the 1950s a new tool was added to the cartographer's art, the new tool was the computer. The 1960s saw more improvement with software that produced good maps for statistical use, by today's standards even these are primitive machines. Computers are faster and more accurate, but the same art is involved. As you know computers had hold a great deal of data and even new improvements are being added as I speak.
B. Like all computer systems computer mapping can be revised without redrawing them and changes can be made before the hard copy is printed. Before the copy is printed the cartographer may zoom in on a section, have scale conversions, projections, symbols, contour intervals, and other things can be changed at will. In some applications like weather forecasting, changes can come quickly. Do people evacuate an area because of an incoming hurricane or do they stay put.
DIGITAL TERRAIN MODELS
C. Computer mapping can make a model called Digital Terrain models with three-dimensional views. This type of model is useful in estimating the amount of rock, oil, or water. (Take a look at Figure 2.28 on p. 59.) Some of these maps are color coded and have true contours. This type of map has been used to map Mars and to train military personal.
GEOGRAPHIC INFORMATION SYSTEMS.
D. Geographic Information Systems, GIS, can be considered a some super data base, collecting information dealing with spatial data and is a very new system. It is a closely tied linkage between computer hardware and software. (Take a look at Figure 2-29 on p. 23 to get some idea how it is done.) Like all computer systems the data is encoded as numbers. It can collate data from different maps and other sources concerning a geographic location into a common data base. In short, the information can be cross-indexed. It is like different transparencies overlayed each other. (See Figure 2.30 on p. 61 and read the cutline )
XVIII REMOTE SENSING OF THE ENVIRONMENT
A. Before the middle of the 19th century the only way to get good maps was to get up close and personal to the area that needed to be mapped. Then, new forms of technology were married, to begin Remote Sensing. Remote Sensing is any recording device that is not in physical contact with the Earth's surface.
B. Remote Sensing can be broken down into two broad categories. Photographic devices using cameras, lens, and film. The other category is Nonphotographic procedures, which create images digitally. A list of numbers which is converted to some type of image. (Take a look at Figure 2.31 on p. 63) Sometimes it is difficult to tell the difference between photographs and other images. One way to tell is to look for scan lines and pixels, but many times with reproductions this is impossible.
THE ELECTROMAGNETIC SPECTRUM--THIS ONE IS IMPORTANT
C. For those whose last contact with science was Mr. Wizard or Bill Nye the Science Guy, a review of the Electromagnetic spectrum might be in order. Electromagnetic waves of various lengths or frequencies make up the electromagnetic spectrum and can be called radiation or energy. The source of radiation can come from the Sun, a flame, an electrical discharge like radio waves, X-Rays, or other sources. No matter the source there is a mixture of waves of many different frequencies. The spectrum can be separated by instruments like simple prisms or more complex devices. About three percent of the total spectrum is in the form of visible light, which is a very narrow band of the spectrum. Other parts of the Electromagnetic spectrum can not be seen by the human eye, but can be detected by special instruments. The most familiar forms are radio waves and light waves. Less familiar are infrared, ultraviolet light, X-rays, and gamma rays. All these waves travel in space at the speed of light and it takes about eight minutes for them to reach the Earth from the Sun. (Take a look at Figure 4.5 on p.99)
AERIAL PHOTOGRAPHS
D. Aerial Photographs were the first use of Remote Sensing and remained the only means of Remote Sensing for many years. It began as a lark in France in 1858 and in the 1860s in America. The problem of huge cameras using glass plates, not film, slow shutter speeds and the unstable balloon platforms, made such photography difficult if not impossible. By the First World War, cameras had shrunk and had increased shutter speeds, roll film or sheet film had replaced glass plates, and most important a stable platform, the airplane was developed. Even more developments were made during the Second World War. Nothing like a war or the threat of war to spur technology.
F. Aerial Photography has two aspects, vertical, straight down, and oblique, taken at an angle. Before computers the only way to get three-dimensional views of the land was to use a stereoscope of two slightly different photographs.
(It could give you headaches.)INFRARED FILMS
E. During World War II high altitude reconnaissance became imperative. It was soon discovered that regular black and white film could not record a shape image. The atmospheric scattering of ultraviolet, violet, and blue causes haze. Near-infrared, NIR cuts haze because it records part of the visible spectrum and the longer-wavelenghth, near-infrared which is invisible to the human eye. Another infrared film was advanced during World War II and it was color infrared film (color NIR) this type of film was first called camouflage-detection film because it can detect living vegetation from dead vegetation. (Take a look at Figure 2-33 on p. 64.) This type of film is blind to blue and the images are false colors, an example would be greens like living vegetation becomes reds, this can further be enhanced by the use of filters. Besides war time uses, it is very useful in surveying the health of vegetation.
XIX NONPHOTOGRAPHIC REMOTE SENSING
A. Not all wavelengths of the electromagnetic spectrum can be recorded by film, NIR film only reaches into the near infrared, other imaging systems are needed to go beyond just plain photography. These systems can combine some of the advantages of NIR film and are called optical-mechanical scanner systems. Nonphotographic sensing is broken down into either passive, which picks up natural radiation, and active which transmits their own energy and is reflected back to the receiver.
THERMAL INFRARED TIR SCANNING
B. The middle part of infrared and the far part of infrared of the electromagnetic spectrum cannot be detected with film. Special sensors are needed, called Thermal Infrared Scanning (TIR). Thermal is a fancy name for heat, and TIR senses the radiant temperature of objects, which can be scanned anytime. A short and dirty definition of TIR could be a map of hot or cold areas. The process is complex, but the image is created line by line using a mirror which focuses heat energy on a supercooled sensor. The heat is recorded on tape and transformed into lines similar to a TV picture. Originally they are in Black and White, but are often colorized. TIR is an expensive process.
C. TIR simulates photographs and is very well-suited for displaying the differences between land and water, between bedrock, and alluvium, (sand and gravel and other forms of overburden,) thermal water pollution, and discovering forest fires in remote locations. It the spatial resolution, what it can pick out, is a few kilometers or even few miles. This is sufficient for weather forecasting from satellites and are the pictures one sees on weather patterns on television. (Take a look at Figure 2.34 on p. 65.)
RADAR
D. Radar is active and an old system, created in the 1940s. It is the acronym for radio detection and ranging. Primitive by todays standards, radar was used to detect aircraft and ships during World War II. Radar sends radio waves longer than 1 millimeter, which bounces off an object and returns to the radar set and the time interval is converted to distance. At first these images could only be seen on something like a TV screen, but are now converted to something like a photograph. It can cut through atmospheric moisture, day or night does not effect its performance. It is used a great deal in terrain evaluation. Other types of radar sets have found ancient water courses in the Sahara, and smaller hand carried units can find buried man made structures. There are several types of radar one of the newest systems is Doppler radar. Which can establish precipitation patterns, the storm track, (the direction) and speed of the storm. To compare two different radar images (Take a look at Figure 2.35 a .)
MICROWAVE SENSING--IMAGING RADAR
E. Another sensing system is something that most people should be familiar with, that is Microwave sensing or Imaging radar. It senses radiation in the 100-micrometer to 1 meter band. The spatial resolution is not great, but it can detect subsurface details like moisture. It is used in topography and can detect subsurface details like moisture, rock, and ice. The microwaves bounce off the surfaces and give different types of pictures. There are times in this world a direct flight over certain countries is not advisable so Side-Looking Airborne Radar (SLAR) was developed, it is similar to oblique, aerial photographs. This system is excellent for terrain and hydrologic mapping areas which are remote, inhospitable, inaccessible, cloudy, heavily forested regions, and places where you might get shot down. (Take a look at Figure 2.35 b.)
MULTISPECTRAL REMOTE SENSING
F. Most systems use only one form of remote sensing, but there are some systems which combine several different systems. These are multispectral or multiband systems. They use different systems in the electromagnetic spectrum and combine them to form an image by using millions of pixels--the smallest image dot of a image system. The Landsat satellites first launched in 1972 are an example of combined systems. Landsat overflies the same place at the same time of day every 16 days. This is important for environmental monitoring.
G. Weather satellites of NOAA, (National Oceanic and Atmospheric Administration) monitor weather patterns in low polar orbits. They use visible light, thermal IR, to record the weather and clouds. The GOESS (Geostationary Operational Environmental Satellite) are in a very high geostationary orbit over the equator an keep track of storm systems. Of course the Air Force, the French, Russians, and Japan have weather satellites.
GUIDED PRACTICE Questions during the lecture.
INDEPENDENT PRACTICE Readings at home
Culmination
What is the system to find locations on Earth?Globes are different than Maps. Which one is more versatile?
Latitude and Longitude differ. Know the directions and how they divide the world.
What time is it GMT or Zulu?
Public Lands Survey System has great impact on what parts of the United States?
How does the Global Positioning System work?
What is the most famous Map Projection and what are the problems involved in that projections. Does it have a use?
What elements does a map need?
List some of the different kinds of Maps?
List the new Modern Mapping Technologies.
What are some examples of Remote Sensing?