25 Making Topographical Maps

Transcription

1 25 Making Topographical Maps i n v e s t i g at i o n A collection of landforms in an area is called its topography (ta-pa-gruh-fee). In Boomtown, there are many different kinds of landforms that make its topography interesting. For example, the street map of Boomtown shows that it has a hill, river, marsh, cliff, and beach. These landforms can be identified because they are labeled on the street map. For places that are not clearly named, or where more information about the landform is needed, a topographical map is useful. A topographical map uses a series of lines to represent the three-dimensional shape of the land surface. Each line represents a specific elevation (el-a-y-shun) above sea level. For example, one line on a topographical map might represent an elevation of 100 meters. Topographical maps can be confusing for those not familiar with them. This activity will help you understand how lines on a topographical map represent the shape of the land. CAENGE hat do the lines on a topographical map show? This topographical map shows roads, trails, creeks, and lakes in addition to elevation. C-8

2 Making Topographical Maps Activity 25 Materials For each group of four students 1 landform model 1 transparent plastic lid 1 dry erase marker 1 15-m bottle of blue food coloring 1 large container of cold water Procedure 1. Place 20 drops of food coloring in your container of water. 2. Place the lid on the box of the landform model and look down at the landform. Use the marker to draw a dashed line on the lid that outlines the edge of the landform. int: It may help to close one eye when you re viewing the box from above. Make sure to keep your head in one place while you re drawing the line. 3. Being careful not to smudge your line, remove the lid and fill the box with water until it reaches the first step on the side of the box. 4. Place the lid on the box and then use the marker to draw at least one line that shows where the water reaches the sides of the landform. 5. abel any line you draw with a Add water until it reaches the next step, and repeat Steps 2 4. abel the line(s) drawn with water filled to the second step with a Add water to the levels of the third, fourth, and fifth steps of the box, repeating Steps 2 4 each time. abel the lines 3, 4, and atch carefully as you add just enough water to cover the top of the landform. Use your observations to place an X on the lid above the highest point. C-9

3 Activity 25 Making Topographical Maps Analysis 1. A contour interval is the change in elevation between adjacent lines. If each water line in your landform model represents 25 meters, what is a. the contour interval for your topographical map? b. an estimated height of the top of the hill? 2. a. hat does your topographical map show you about the land? b. hat does your topographical map not show you about the land? 3. Compare the following diagrams that were each drawn with the same contour interval and scale. a. hich one shows a fairly flat area? b. hich one shows a hill or a valley with a gentle slope? c. hich one shows a steep hillside? A. x yb. zc. 4. ook at the diagram below and answer the following questions. a. hat kind of landform is this? b. hich of the locations marked on the map is the steepest? c. hich of the locations marked on the map is the flattest? M 20 N C-10

4 26 Boomtown s Topography p r o b l e m s o lv i n g An important part of evaluating a building site is determining the stability of the land. Stable areas have landforms that have not changed much over a long time. One way to learn about recent changes to the land surface is to compare the present day topography with past topography. Although Boomtown has grown quickly in the last twenty years, it was only a small town one hundred years ago. The Boomtown ibrary has maps that can show you how the area looked in the past. CAENGE hat can topographical maps tell you about the stability of a building site? Materials For each pair of students 1 Student Sheet 26.1, Maps of Boomtown 100 Years Ago 1 Student Sheet 26.2, Maps of Boomtown 20 Years Ago 1 Student Sheet 26.3, Maps of Boomtown Today C-11

5 Activity 26 Boomtown s Topography Procedure 1. Each student sheet shows a street map and a topographical map of Boomtown at different times: 100 years ago, 20 years ago, and today. 2. In your science notebook, make a table like the one below. 3. Carefully examine the maps and compare one location at a time. Boomtown through Time ocation 100 years ago 20 years ago Today Marsh illside Cliff Observe changes in roads and buildings waterways landforms 4. Discuss any changes you see in the maps with your partner. Record your observations in your table. 5. After observing all the maps, discuss your ideas with the other pair in your group of four. Review your table together and add any new observations of the three building sites. C-12

6 Boomtown s Topography Activity 26 Analysis 1. hat is the contour interval in the topographical maps of Boomtown? 2. a. hat major changes did you observe between 100 years ago and 20 years ago? b. hat major changes did you observe between 20 years ago and today? 3. ook at the maps of the three locations in Boomtown. a. hich of the three locations is the most stable? b. hich of the three locations is the least stable? c. Explain the evidence that supports your answers to 3a and 3b above. 4. Do the maps indicate possible problems for building at any of the possible locations? C-13

7 69 Forecasting eather i n v e s t i g at i o n You have learned that meteorologists collect data about the earth s weather. They often use that data to construct weather maps. Meteorologists then use those maps to predict what the weather will be like in the next few hours, the next day, or for the next several days. This is known as a weather forecast. hen forecasting weather, meteorologists sometimes refer to cold fronts, which form when cold air moves in and replaces warm air. The cold air pushes the warm air up, forming high columns of clouds, as shown below. Cold fronts usually cause cooler temperatures. A warm front occurs when warm air moves in and replaces cooler air. arm fronts bring in warmer temperatures. They also create cloudy conditions that usually last longer than the cloudy conditions produced by cold fronts. CAENGE hat information is found on a weather map? ow can a weather map be used to forecast weather? Cold Front arm air mass Cold air mass arm Front arm air mass Cold air mass E-84

8 Forecasting eather Activity 69 Materials For each student 1 Student Sheet 69.1, Summarizing eather Reports 1 Student Sheet 69.2, Map of Iowa Procedure 1. ork with your group to review the information in the table below, eather Map Symbols. Make sure that you are familiar with the different weather symbols and what they mean. eather Map Symbols eather Symbol Associated eather Precipitation Rain, snow, fog, or other forms of precipitation Cold front Cooler temperatures, possible precipitation arm front armer temperatures, possible precipitation ow pressure igh pressure urricane Cloudy skies, possible precipitation Clear skies Damaging winds, rain, possible flooding Tornado watch Area where tornadoes may occur, possible severe thunderstorms Tropical storm Very strong winds and heavy rains 2. Your teacher will assign your group one of the weather maps for August shown on pages E-85

9 Activity 69 Forecasting eather 3. ork with your partner to summarize the weather on this map. Identify: weather fronts precipitation areas of high and low pressure any unusual weather events, such as a tornado watch or a hurricane Be sure to discuss with your partner each type of weather and where in the country it is occurring. For example, if you were to begin to summarize the weather for August 24, you might say, There is a cold front stretching from Arizona northeast up to Minnesota. 4. ork with your partner to write a weather report for your assigned day. You can do this by describing the weather that is associated with each weather symbol (see the table). As you summarize current weather conditions, make sure to describe: weather fronts and possible changes in temperature areas of precipitation clear or cloudy skies due to changing pressure any unusual weather events, such as a tornado watch or a hurricane In your science notebook, write your weather report in complete sentences and in the present tense, as if you were reporting the weather on television or the radio. For example, if you were to begin to summarize the weather on August 24, you could write, The cold front stretching from the southwest up to Minnesota is causing cooler temperatures and may result in some precipitation. 5. Share your weather report with the other half of your group. Discuss similarities and differences in your weather reports, and make any needed changes. 6. Prepare one weather report to present to the class. 7. Read the statements on Student Sheet 69.1, Summarizing eather Reports. You will respond to these statements after listening to your classmates report on the weather for each of the eight days from August 24 to ave your group present its weather report and listen to other groups reports. 9. After listening to all eight weather reports, complete Student Sheet E-86

10 Forecasting eather Activity 69 ocator Map for Cleveland, Ohio Pacific Ocean A. Superior. Michigan. Ontario. uron N S E CAIF AZ YO COO N X OKA TEX MO ARK A I MISS. Erie Cleveland KY AA GA DE Atlantic Ocean FA Gulf of Mexico 10. Based on the weather reports you heard, forecast the weather for Cleve - land, Ohio for September 1. Describe likely fronts, temperature changes, pressure changes, precipitation, and severe weather that may arrive. int: ook at the pattern of weather over the eight days. Use your knowledge of how weather moves across the United States to predict what type of weather is likely to occur in Cleveland. Analysis 1. a. Based on the patterns you observed in the weather maps, in what direction does weather generally travel across the United States? b. Think back to your work in the last activity. In what direction does the prevailing wind move across the United States? c. ow does the movement of the atmosphere globally affect weather locally? 2. Below is weather data collected for Iowa on September 15. Your teacher will give you Student Sheet 69.2, Map of Iowa. Use the information provided and your knowledge of weather maps to place the appropriate weather symbols on Student Sheet Be sure to construct a key for your map. arm front extending from incoln, Nebraska northeast to Mason City, Iowa Rain all along the warm front ow-pressure system in and around Des Moines, Iowa 3. Reflection: People often complain about the unreliability of weather forecasts. hy do you think meteorologists are sometimes wrong about what the weather will be like? E-87

11 Activity 69 Forecasting eather A CAIF AZ August 24 YO COO N X TEX OKA MO ARK A I KY MISS AA GA FA DE eather Maps: August 24 through August 31 A CAIF AZ August 25 YO COO N X I MO KY OKA ARK MISS AA GA TEX A FA DE A CAIF AZ August 26 YO COO N X I MO KY OKA ARK MISS AA GA TEX A FA DE A CAIF AZ August 27 YO COO N X I MO KY OKA ARK MISS AA GA TEX A FA DE E-88

12 E-89 Forecasting eather Activity 69 COO OKA A ARK MO YO I AA MISS KY TEX N X GA FA AZ CAIF A DE COO OKA A ARK MO YO I AA MISS KY TEX N X GA FA AZ CAIF A DE COO OKA A ARK MO YO I AA MISS KY TEX N X GA FA AZ CAIF A DE COO OKA A ARK MO YO I AA MISS KY TEX N X GA FA AZ CAIF A DE August 28 August 29 August 30 August 31