2. Maps
Contents
2.1 A map is a representation of a territory
A map is an image that gives a simplified, minimized view of a territory.
Things found in the terrain are represented on the map as symbols. The scale of a map portrays distances by telling you how many real-world centimeters one centimeter on the map represents.
You can understand the difficulty of representing planet Earth on a two-dimensional map by peeling an apple and laying out the peel flat on a table. You will notice that the peel is not a uniform flat rectangle, but that it leaves empty spaces near its edges. However, such a problem is not found on globes, because they represent Earth by replicating the planet's globular shape.
2.2 Different map projections
A world map that uses the Mercator projection.The Mercator projection is a type of map projection that is widely used due to the fact that it reproduces the shapes of the continents accurately. However, the downside of the Mercator projection is that it makes areas near the two polar regions look larger than they actually are. For example, when using the Mercator projection, the Antarctic looks like the largest continent on the world.
A world map that uses the Robinson projection.
In the Robinson projection, the surface areas are almost correct everywhere in the world, but the shapes of the continents are somewhat askew. Therefore, when studying a two-dimensional map, it is important to keep in mind that everything is not always presented completely accurately. Both the Mercator projection and the Robinson projection present the Antarctic inaccurately.
You can use the Seterra site to hone your skills in recognizing continents, nations, cities, flags, etc.
Seterra geography exercisesMap of the world
a) Can you discern where the equator is?
b) Turn the map into a position that is centered on the Arctic Pole. Can you find Finland or Florida?
c) Turn the map into a position that is centered on the Antarctic Pole. Can you discern the southernmost tip of South America? What about Australia?
2.3 Longitudes and latitudes
When you look at a world map, you will notice horizontal and vertical lines running across the Earth. The horizontal lines, running between from west to east, are called latitudes. The latitudes travel in the same direction without ever touching each other. The longest of these lines is the equator, which divides planet Earth into its northern (N) and southern (S) hemispheres. The latitude of the equator is marked as 0 degrees.
When moving away from the equator in either northward or southward direction, the degrees of latitude begin to increase. The latitude of the North Pole is 90° N, whereas the latitude of the South Pole is 90° S.The vertical lines on the map run between the planet's North and South Poles. They are called longitudes. The zero longitude is marked to run through London's Greenwich, and is called the Greenwich meridian. It divides the planet into an Eastern (E) and Western (W) hemispheres.
Because the perimeter of a round object is 360 degrees and the Greenwich meridian divides our planet in half, the largest possible longitude is therefore 180°. The longitudes of 180° E and 180° W meet each other on the opposite side of the planet from Greenwich, in the middle of the Pacific Ocean.
The Greenwich meridian is also the basis for the Earth's time zone system. All clock times on planet Earth are compared to Greenwich Mean Time (GMT) or Coordinated Universal Time (UTC). The place where the two 180 latitudes meet is called the date line. When moving over this line, you will move to the next or the previous day (depending on the direction you are travelling) because of the Earth's time zone system.
2.4 Coordinates determine your location on the map
When the lines of latitude and longitude are placed on a map, a coordinate grid is formed. As a result, a location on the map can be presented as degrees of latitude and longitude, or coordinates.
The latitude, or distance from the equator, is always presented first. The longitude, or distance from the Greenwich meridian, is always presented second.
A map of the world. The coordinates of Istanbul are 40 degrees north (latitude; 40° N) and 30 degrees east (longitude; 30° E), whereas the coordinates of Helsinki are 60°N 24°W, those of Philadelphia are 40°N 75°W, and those of Belo Horizonte are 20°S 44°W.
2.5 Scales help you calculate distances
To use a bar scale, you need the help of a ruler. If the bar is 5 centimeters long and contains the number 100 km, 5 cm on the map represents 100 km in the real world, meaning that 1 cm is 20 km.
The scale can also be presented as a ratio. The ratio shows the relation between a centimeter on the map and a centimeter in the real world. For example, if the scale of the map is 1 : 250 000, 1 cm on the map represents 250 000 cm in the real world. When you convert this number to kilometers, you will see that 1 cm on the map represents 2,5 km in the real world.
The distance between San Francisco and New York is 8 cm on the map. The scale is 1:50 million. This means that one centimeter on the map represents 50 million centimeters or 500 kilometers. The distance between the two cities is therefore 8 x 500 km= 4 000 km.
2.6 Satellite image
Below, you will find a satellite image of Europe.
Satellite images are particularly useful when studying population density, as seen in the video below.
Shutterstock.com/NASA
Summary
• A map is a reduced, simplified image of a territory.
• A map should always include a scale, so that the distances between different places can be calculated.
• Different map projections strive to present Earth on a two-dimensional plain as accurately as possible.
• The equator divides planet Earth into Northern (N) and Southern (S) Hemispheres.
• The zero meridian at Greenwich divides planet Earth into Eastern (E) and Western (W) Hemispheres.
• Latitudes run over Earth horizontally, and their degrees can range from 0 (the equator) to 90 (the North and South Poles).
• Longitudes run over Earth vertically, and their degrees can range from 0 (Greenwich) to 180 (the Pacific date line).
• Together atitudes and longitudes create a coordinate grid, which makes it possible to present a location on the planet by using coordinates.