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        6-8

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        Regional Patterns of Climate: Pacific Northwest

        Explore how factors such as wind patterns, landforms, and geographic location near the ocean influence regional climate in this lesson plan from WGBH. Learn how rain shadows form through an interactive lesson. Watch animated data visualizations of wind patterns and make connections between atmospheric circulation and climate. Analyze and interpret temperature and precipitation data of different cities to explore how proximity to the ocean influences weather and climate patterns.

        English Learner (EL) supports are included in the Support Materials below. These are designed to support vocabulary development and engagement in learning tasks and can be used along with this lesson plan. This resource was developed through WGBH’s Bringing the Universe to America’s Classrooms project, in collaboration with NASA. Click here for the full collection of resources.

        Lesson Summary

        Overview

        In this lesson, students use media to explore and investigate how factors such as landforms, proximity to the ocean, and wind circulation affect regional climate. They focus on the Hoh Rain Forest in the Pacific Northwest as a case study. Through an interactive lesson, they explore the phenomenon of rain shadows and the effect that mountains can have on a region’s precipitation. They then investigate how the polar jet stream and the ocean influence temperature and precipitation patterns. As a summarizing activity, students apply their learning to communicate the process of rain shadow formation using satellite images.

        Grade Level: 6-8

        Standard: ESS2.D: Weather and Climate

        • Weather and climate are influenced by interactions involving sunlight, the ocean, the atmosphere, ice, landforms, and living things. These interactions vary with latitude, altitude, and local and regional geography, all of which can affect oceanic and atmospheric flow patterns. (MS-ESS2-6)

        Time Allotment

        Two 45-minute class periods

        Learning Objectives

        • Students will be able to relate geography, wind circulation, and regional climate.
        • Students can use media to describe the temperature and precipitation patterns of specific regions.
        • Students can model the effects of mountains on regional climate.

        Prep for Teachers

        Before the Lesson

        • Arrange to have computer access for students to work individually or in small groups.
        • Download and print the rain shadow satellite images from the Rain Shadows resource. 

        Supplies

        Materials

        • Computer or tablet access 
        • Markers or colored pencils 

        Handouts

        Media Resources

        Learning Activities

        Engage 

        1. Begin the lesson by asking students what they think of when they hear the words “rain forest.” Ask:
            • What do you imagine a rain forest looks like?
            • What kind of weather comes to mind?
            • Where do you think most rain forests in the world are located?
        1. Tell students that there is a rain forest located in the United States, in the state of Washington. (Point out Washington on a map, if necessary.) Have students view The Landscape of the Pacific Northwest gallery, which includes images of the Pacific Northwest region and the Hoh Rain Forest within Olympic National Park on the Olympic Peninsula of Washington State. 
        1. In the panorama of the Pacific Northwest, have students look for geographic features such as land, water, and mountain ranges. Have students note the “green region” and “brown region,” and point out the approximate location of the Hoh Rain Forest—the dark green triangular region within the Olympic Peninsula. Ask:
            • What observations can you make about the Pacific Northwest? 
            • What land features do you see?
            • What do the green and brown colors mean? 
            • Where is the ocean with respect to the green and brown regions?
            • How might conditions for plant life differ between the green and brown regions?
            • How does the climate vary between the two distinct regions?
            • What do you think produces such differences?
        1. As students study the scenes within the rain forest, ask:
            • How would you describe the scenery within the Hoh Rain Forest? What do the trees and other vegetation look like?
            • What do you infer temperature and rainfall conditions must be like to allow such vegetation to grow?
        1. Discuss as a class the climate of the local region in which you live. Have students share experiences they had with different climates if they’ve traveled to other parts of the country or abroad. Remind students that the difference between weather and climate is time. Both refer to atmospheric conditions such as temperature, precipitation, cloudiness, and wind for a particular location. However, weather describes short-term conditions, such as what’s happening today, tomorrow, or 10 days from now; weather varies by season and can change day by day or even minute by minute. Climate, on the other hand, describes general conditions over relatively long periods of time.

        1. Bring the discussion back to the panoramic image of the Pacific Northwest and tell students that in this lesson, they will explore how geographic features influence the weather and climate of a region.

        Explore/Explain

        1. Have students engage individually with the Mountains and Rain Shadows interactive lesson. In this interactive lesson, students explore the processes of evaporation and condensation in the atmosphere and how air masses interact with mountain ranges to produce drastically different regional temperature and rainfall patterns. At the end of the interactive lesson, students apply what they learn to create their own model (a computer-generated diagram) of the rain shadow phenomenon. The interactive lesson should take students about 20 to 30 minutes to complete.

        1. Page-specific notes:
            • Page 2: Students should be able to observe that in each image, one side of the mountain range is greenish in color, while the other side is brownish. Green regions indicate vegetation cover; brown regions indicate lack of vegetation. Based on their observations, students should be able to infer that the climate on either side of a mountain range is dramatically different—climate conditions are favorable for vegetation to grow on one side, but not on the other.
            • Page 3: Sample answer: As the winds carry the air mass across the ocean toward land, its moisture content increases.
            • Page 5: Sample answer: The air becomes drier.
            • Page 7: Sample answer: There is greater annual rainfall in Packwood on the windward side, with a mean of 56 inches, compared to 8 inches for Yakima on the leeward side. The variation in temperature throughout the year is greater on the leeward side—26.9°F versus 19.5°F on the windward side. Therefore, the climate of windward regions will be wetter and have milder winters due to the smaller temperature swing; leeward regions will be drier and warmer. The satellite image shows more plant life growing on the windward side.
            • Page 9: Encourage students to add as many details, including text labels, to their model as possible using the tools provided.
        1. After students have completed the interactive lesson, discuss the role of winds in carrying moisture-laden air from over the ocean to land—in this case, from the Pacific Ocean over the western coast of Washington. As a class, watch the Jet Streams over North America video in the Jet Streams resource. Focus on the video timeframe from about 0:11 to the end. Point out that the colors represent wind speeds, with the fastest winds colored red and slower winds shown in blue.
        1. Have students share their observations of the motion of the polar jet stream (the prominent jet stream visible in the video clip), describing its direction and pattern over the western United States. Guide students to make connections between the polar jet stream and the rain shadow effect in the Pacific Northwest.
        1. Next, have students explore the Precipitation in the Pacific Northwest resource to study rainfall patterns for Washington State. Have students locate regions of highest and lowest precipitation. What connections can they make between geography—different parts of the state and apparent surface features—and the amount of rainfall?
        1. Explain to students that one of the defining factors of a rain forest is high annual precipitation. In the tropical zone around the equator (between 23.5°N and 23.5°S), rain forests typically have annual rainfalls of over 78 inches (200 cm) per year. Rain forests found in the temperate zones (23.5°N to 66.5°N and 23.5°S to 66.5°S) typically have more than about 55 inches (140 cm) of rain per year.
        1. To explore how proximity to the ocean affects climate, distribute the How Does Proximity to the Ocean Influence a Region’s Climate? handout. In this activity, students are able to compare the temperature and precipitation patterns of two pairs of cities; in each pair, one city lies on the Pacific coast while the other is farther inland, at a similar latitude. Answers:
         

        Seattle, WA

        Glasgow, MT

        Crescent City, CA

        Des Moines, IA

        Latitude

        48°N

        48°N

        42°N

        42°N

        Coastal or inland?

        Coastal

        Inland

        Coastal

        Inland

        Annual total precipitation

        37.47 in

        11.66 in

        71.24 in

        36.02 in

        Lowest average temperature

        42.0°F (January)

        13.8°F (January)

        46.4°F (December)

        22.6°F (January)

        Highest average temperature

        76.3°F (August)

        71.1°F (July)

        58.3°F (August)

        76.3°F (July)

        Seasonal temperature variation (highest average temperature minus lowest average temperature)

        34.3°F

        57.3°F

        11.9°F

        53.7°F

          1. Seattle and Glasgow (48°N); Crescent City and Des Moines (42°N)
          2. Sample answer: Comparing cities at similar latitude ensures that the patterns observed are not due to differences in latitude—for example, the amount of sunlight received.
            Remind students about the phenomenon of sunlight-driven latitudinal banding, if necessary. The Sun heats Earth’s surface unevenly due in part to the spherical shape of the Earth, Earth’s tilt on its axis, and its orientation relative to the Sun. Climate varies with latitude—regions near the equator receive relatively large amounts of solar energy year round and are generally warmer, while polar regions are colder. Temperate and polar regions experience significant variations depending on the time of year.
          3. Sample answer: In each pair of cities, the coastal city has much higher annual precipitation.
          4. Inland cities have greater seasonal temperature variation compared to coastal cities.
          5. Sample answer: The coastal cities generally have smaller ranges in daytime and nighttime temperatures than the inland cities.
          6. Sample answer: Based on the data, the cities closer to the Pacific Ocean have a milder climate than the cities farther inland at the same latitude. The coastal cities experience higher precipitation, and the temperature throughout the year stays within a smaller range than the cities in the middle of the continent.
        • Students should be able to come to the conclusion that regions closer to the ocean (and in this case, on the windward side of the Pacific mountain system) have higher precipitation and show less variation in temperatures in general.
        • Explain to students that the ocean has a tempering effect on a region’s climate. The ocean absorbs most of the Sun’s energy and retains the heat; it then releases it slowly compared to land. This results in coastal regions having smaller temperature variations between day and night, and between winter and summer, compared to regions farther inland.

        • Note:
          Water has a much higher heat capacity than land—it takes more energy and more time to warm the ocean than to warm land by the same amount. This also means that the ocean stores more energy and holds on to heat longer than land. Because the ocean is a fluid, energy input gets mixed and penetrates many meters into the ocean, whereas only a thin upper layer of solid earth gets heated directly.

        Elaborate

        1. Have students apply their understanding of the rain shadow phenomenon by annotating satellite images of various mountains and their corresponding rain shadows. Distribute the satellite images of rain shadows from the Rain Shadows resource. Have students illustrate/label the process of rain shadow formation directly on the images. For example, they can draw arrows to represent winds and uplift or add labels to indicate wet and dry regions. Students should be sure to identify the direction of prevailing winds. Prevailing wind directions and some geographic features are labeled in Rain Shadows: Annotated Satellite Images document.

        Evaluate

        1. Have students answer the question, Why is there a rain forest in the Pacific northwest of the United States? They should write a paragraph describing (in their own words) how the regional climate of the Pacific Northwest is affected by factors that include the Cascade Mountains, location near the Pacific Ocean, and the jet stream. 

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