Use coordinates and multiple criteria to compare regions

Learning goal: Read latitude and longitude, make qualified climate generalizations and define regions using stated evidence. A region is an area grouped by one or more characteristics. Different questions can produce different regional boundaries for the same part of the world.

Latitude measures position north or south of the equator as an angle, in degrees. The equator is zero degrees latitude; the poles are ninety degrees north and south. Two more named lines of latitude are the Arctic Circle, at about 66.5 degrees north, and the Antarctic Circle, at about 66.5 degrees south. Lines of equal latitude circle the globe east–west. A location at twenty degrees north is north of the equator, even though the latitude line itself extends around the globe.

Longitude measures position east or west of the prime meridian as an angle, in degrees, which is zero degrees longitude. Longitude lines meet at the poles. State both the number and the direction, such as sixty degrees west. A coordinate pair normally gives latitude first, then longitude. Omitting north/south or east/west can identify a different location.

The fictional coordinate diagram places A at twenty degrees north, sixty degrees west; B at twenty degrees south, sixty degrees west; and C at twenty degrees north, one hundred degrees west. A and B share longitude but lie on opposite sides of the equator. A and C share latitude, while C is farther west. These are practice points, not labeled cities or measured climate stations.

Latitude supports broad climate generalizations because incoming sunlight differs with latitude over the year. Low-latitude regions are generally warmer than high-latitude regions. However, elevation, ocean influence, winds and other factors also matter. A high mountain near the equator can be colder than a lowland location farther from the equator. Longitude alone does not provide a simple warmer-to-colder rule.

Climate describes long-term patterns, not one day's weather. To compare two regions, use observations summarized over an appropriate span and consistent measures. One rainy afternoon does not prove that a place has a wetter climate than another. Check whether a map shows annual precipitation, a seasonal average or a single storm before interpreting its colors.

Regions can be defined by physical criteria such as landform and climate, or by human criteria such as population, language patterns and economic activity. The Andes form a mountain region crossing national borders. The Amazon drainage basin is defined by water flowing through a connected river system. Political countries use another kind of boundary. One place can belong to several overlapping regions at once.

Human patterns rarely stop neatly at every boundary on a classroom map. A language may be spoken on both sides of a national border, and several languages may be used within one country. An agricultural region can contain cities and industrial work as well as farms. A regional label summarizes selected characteristics; it does not describe every resident or eliminate variation.

To build a regional comparison, choose criteria first and record the data supporting them. Suppose a fictional classification uses elevation above a stated threshold to identify a highland region. Changing the threshold can move the boundary. Explain that choice and compare another criterion, such as population density, to see how the pattern changes. Do not present your chosen categories as the only possible natural division of the world.

Here is an invented data table for six squares of a fictional map; the numbers describe no real place. Square 1: elevation 3,200 m, rainfall 600 mm a year, 15 people per square kilometer, Language A, herding. Square 2: 2,600 m, 700 mm, 120 people, Language B, farming. Square 3: 2,100 m, 900 mm, 40 people, Language A, farming. Square 4: 300 m, 2,500 mm, 8 people, Language B, forestry. Square 5: 150 m, 2,200 mm, 300 people, Language B, manufacturing. Square 6: 1,800 m, 1,000 mm, 60 people, Language A, farming. Each criterion draws a different region. Landform (elevation of 2,000 m or more) gives a highland region of squares 1, 2 and 3. Climate (rainfall of 2,000 mm or more) gives a wet region of squares 4 and 5. Population (100 people or more per square kilometer) gives squares 2 and 5. Culture (Language A) gives squares 1, 3 and 6. Economic activity (farming) gives squares 2, 3 and 6. The highland region and the Language A region overlap in squares 1 and 3 but are not the same region, so a map must name the criterion and the data behind each boundary.

Worked coordinate reading: A at 20° N, 60° W is north of the equator and west of the prime meridian. B at 20° S, 60° W shares the same longitude but differs by forty degrees of latitude. Degrees are angular units, not kilometers on this flat practice grid.

Worked region from data: In the invented six-square table, a highland region drawn from elevation (2,000 m or more) is squares 1, 2 and 3, while a farming region drawn from economic activity is squares 2, 3 and 6. The two regions share squares 2 and 3. Square 1 is highland but not farming, and square 6 is farming but not highland, so each region needs its own label and criterion.

Worked region comparison: A mountain region and a national territory can overlap without having identical boundaries. The first uses landform evidence; the second uses political boundaries. A map should name the criterion so the reader understands why the outline was drawn.

Guided investigation: On a globe and a dated atlas map, locate the equator, prime meridian, one North American place and one South American place. Record coordinates with directions. Compare a climate map and an elevation map for those places, identifying a general pattern and a factor that complicates it.

Independent performance: Define two overlapping Western Hemisphere regions, one from physical data (landform or climate) and one from human data (population, a cultural characteristic such as language, or economic activity). Cite the data source for each, mark the squares or places that meet each criterion and explain one within-region difference. Plot provided coordinates, critique a claim based only on latitude and distinguish long-term climate evidence from a single weather observation. Do not calculate ground distance from the fictional grid's rectangular spacing.