For example, you can investigate the relationship between ethnicity and income in presidential voting patterns. Maps tell stories Maps provide a powerful way to tell many kinds of stories. Story maps make it easy to tell rich, map-based stories in the form of self-contained web apps. These web apps combine intelligent web maps with text, photos, video, and sound to elucidate interesting topics, like this map of endangered languages of the world linked to audio from native speakers.
Maps can display dynamic information that changes over time In GIS, many maps can dynamically display time frames, much like a weather map. Click the play button to animate the seasonal imagery over the past 12 months. GPS can get you from point A to point B but it does a poor job with helping you vis ualize where you are in relation to everything else. Most people know how GPS works. It finds your location and you tell it where you want to go.
Maps support spatial thinking by helping children visualize where objects, places, cities, and countries are in relation to one another. Spatial thinking has been linked to greater success in math and science. Children who develop robust spatial thinking skills will be at an advantage in our global and technological society.
As we start shaping their education and preparing them for the future, map reading skills help children gain proficiency in the principles of geography. According to The National Park Service NPS , there are more than million people visiting national parks, forests, and wilderness areas every year.
A paper map may actually save your life. There have been multiple cases that deal with accidents related to GPS. This applies to other aspects of our lives as well.
The more we pay attention to the device, the less we pay attention to our surroundings. Maps, on the other hand, ground you to your surroundings. Also called a bar scale , it is simply a horizontal line marked off in miles, kilometers, or some other unit measuring distance. The verbal scale is a sentence that relates distance on the map to distance on Earth. This means that any given unit of measure on the map is equal to one million of that unit on Earth. So, 1 centimeter on the map represents 1,, centimeters on Earth, or 10 kilometers.
One inch on the map represents 1,, inches on Earth, or a little less than 16 miles. The size of the area covered helps determine the scale of a map. A map that shows an area in great detail, such as a street map of a neighborhood, is called a large-scale map because objects on the map are relatively large. A map of a larger area, such as a continent or the world, is called a small-scale map because objects on the map are relatively small.
Today, maps are often computerized. Many computerized maps allow the viewer to zoom in and out, changing the scale of the map. A person may begin by looking at the map of an entire city that only shows major roads and then zoom in so that every street in a neighborhood is visible. Symbols Cartographers use symbols to represent geographic features. For example, black dots represent cities, circled stars represent capital cities, and different sorts of lines represent boundaries, roads, highways, and rivers.
Colors are often used as symbols. Green is often used for forests, tan for deserts, and blue for water. A map usually has a legend , or key, that gives the scale of the map and explains what the various symbols represent.
Some maps show relief, or changes in elevation. A common way to show relief is contour lines, also called topographic lines. These are lines that connect points that have equal elevation.
If a map shows a large enough area, contour lines form circles. A group of contour line circles inside one another indicates a change in elevation. As elevation increases, these contour line circles indicate a hill. As elevation decreases, contour line circles indicate a depression in the earth, such as a basin. Grids Many maps include a grid pattern, or a series of crossing lines that create squares or rectangles.
The grid helps people locate places on the map. On small-scale maps, the grid is often made up of latitude and longitude lines. Latitude lines run east-west around the globe , parallel to the Equator , an imaginary line that circles the middle of the Earth.
Longitude lines run north-south, from pole to pole. Latitude and longitude lines are numbered. The intersection of latitude and longitude lines, called coordinates , identify the exact location of a place. On maps showing greater detail, the grid is often given numbers and letters.
The boxes made by the grid may be called A, B, C, and so on across the top of the map, and 1, 2, 3, and so on across the left side. The user finds the park by looking in the box where column B and row 4 cross. Title, date, author, and sources usually appear on the map though not always together.
A map of areas threatened by a wildfire, for instance, would have a date, and perhaps even a time, to track the progress of the wildfire. A historical map of the ancient Sumerian Empire would have a date range of between 5, B. Assessing accuracy and objectivity also requires checking sources. A map of a school district may list the U. Orientation refers to the presence of a compass rose or simply an arrow indicating directions on the map. If only an arrow is used, the arrow usually points north.
Map Projections Transferring information from the spherical , or ball-shaped, surface of Earth onto a flat piece of paper is called projection. A globe, a spherical model of Earth, accurately represents the shapes and locations of the continents. But if a globe were cut in half and each half were flattened out into a map, the result would be wrinkled and torn. The size, shape, and relative location of land masses would change.
Projection is a major challenge for cartographers. Every map has some sort of distortion. The larger the area covered by a map, the greater the distortion. Features such as size, shape, distance, or scale can be measured accurately on Earth, but once projected on a flat surface only some, not all, of these qualities can be accurately represented.
For example, a map can retain either the correct sizes of landmasses or the correct shapes of very small areas, but not both.
This determines which projection to use. For example, conformal maps show true shapes of small areas but distort size.
Equal area maps distort shape and direction but show true relative sizes of all areas. There are three basic kinds of projections: planar, conical, and cylindrical. Each is useful in different situations. Imagine touching a globe with a piece of cardboard, mapping that point of contact, then projecting the rest of map onto the cardboard around that point.
They are often used for maps of one of the poles. Imagine you wrapped a cone around Earth, putting the point of the cone over one of the poles. That is a conical projection. The cone intersects the globe along one or two lines of latitude. When the cone is unwrapped and made into a flat map, latitude lines appear curved in circles or semicircles.
Lines of longitude are straight and come together at one pole. In conical projection, areas in the mid-latitudes—regions that are neither close to the Equator nor close to the poles—are represented fairly accurately. For this reason, conical projections are often used for maps of the United States, most of which lies in the mid-latitudes. The cylinder touches Earth along one line, most often the Equator.
When the cylinder is cut open and flattened into a map, the regions near the Equator are the most accurate. Regions near the poles are the most distorted. But with a map, all of the numbers, patterns and correlations are right in front of you.
It's a graphic language. It presents information in hopefully a way that is very easy to understand. It's the job of a mapmaker, or cartographer , to put all of this information into a format that people can understand and learn from. Exactly what a person can learn depends on the type of map.
Most maps start with an outline of a location, like a piece of land or a body of water. Then, they provide information about the location's attributes. Different maps incorporate different attributes. For example:. This combination of locations and attributes makes it possible to put lots of information into a very small space.
A single map can show you all of the countries on a continent, their borders, their approximate populations and their primary imports and exports. People can also use specialized thematic maps to analyze trends and patterns in all kinds of data. A map showing communication costs in different parts of the world, for example, could help a nonprofit organization decide where to build a low-cost wireless network.
As Turner explains, "Maps are more than about capitals and countries — it's really about how economics and climate and natural features, how all the different variables that make up a society relate to one another.
Common conventions help cartographers present all this information in a way that makes sense. We'll look at them in more detail in the next section. Even though they can incorporate diverse sets of data, maps usually follow several basic conventions that help people make sense of them right away.
Turner explains, "[One convention] used in cartography on political maps, on most maps is that the water is blue. It can throw people when you try to use a different color to signify something like water. Maps depict their subject matter from above and use lines and color to differentiate between regions. Political maps tend to use similar symbols and type sizes to indicate borders, cities and other objects.
On many, but not all, maps, north is at the top — other maps often include an arrow to indicate directions. Most maps have a legend explaining their symbols, and many have a scale noting relationship between the size of the map and the size of the real world, such as 1 inch to miles. Some maps express scale as a ratio, such as , Most maps also include some kind of coordinate system to help people find specific locations.
On a street map of a city, this might be a simple grid marked with letters and numbers. Larger maps usually use imaginary lines known as longitude and latitude. On a globe, these lines are orderly and evenly spaced. All lines of longitude, or meridians, run in a north-south direction are the same length. The lines of latitude, or parallels, all run east and west and are shorter the farther they are from the equator. Maps, on the other hand, can wreak havoc on the parallels and meridians.
This is because Earth is shaped roughly like a pumpkin and getting a flat piece of paper to accurately resemble the entire surface of a pumpkin isn't easy.
You can get an idea of the difficulties involved by drawing a picture on an inflated balloon. Then, stretch the deflated balloon until it lies flat. You can still imagine what the original picture looked like, but the sizes and shapes are all wrong. You can make the deflated picture a little more accurate by cutting it into pieces so that the balloon resembles the gores used to make spherical globes from flat paper. Unfortunately, the resulting series of pointed segments still doesn't look much like the original picture.
Adjacent parts don't touch each other, and you have to imagine what they would look like without the gaps. To get around the shortcomings of flat paper, cartographers use a variety of map projections. We'll explore them in the next section. Using degrees, minutes and seconds, meridians measure how far east or west a location is from the Prime Meridian. Parallels measure how far north or south a location is from the equator. Even though they are easy to fold up and carry around, neither greatly distorted maps nor disassembled globe gores have much practical use.
For this reason, cartographers have developed a number of map projections , or methods for translating a sphere into a flat surface. No projection is perfect — they all stretch, tear or compress the features of Earth to some degree. However, different projections distort different qualities of the map. Creating a map projection is often a highly mathematical process in which a computer uses algorithms to translate points on a sphere to points on a plane.
But you can think of it as copying the features of a globe onto a curved shape that you can cut open and lay flat — a cylinder or a cone. These shapes are tangent to, or touching, Earth at one point or along one line, or they are secant to Earth, cutting through it along one or more lines. You can also project portions of Earth directly onto a tangent or secant plane. Projections tend to be the most accurate along the point or line at which they touch the planet.
Each shape can touch or cut through the Earth at any point and from any angle, dramatically changing the area that is most accurate and the shape of the finished map. Some projections also use tears, or interruptions , to minimize specific distortions.
Unlike with a globe's gores, these interruptions are strategically placed to group related parts of the map together. For example, a Goode homolosine projection uses four distinct interruptions that cut through the oceans but leave major land masses untouched.
Different projections have different strengths and weaknesses. In general, each projection can preserve some, but not all, of the original qualities of the map, including:. You can learn more about the specific map projections and their strengths and weaknesses from NASA , and the U.
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