Background:
The extreme climate of Death Valley is attributable to its location on the leeward (downwind) side of the Sierra Nevada Mountains in central California. Air that has been warmed and moistened by its passage over the Pacific Ocean is driven up over the Sierras as it is carried eastward by the prevailing southwesterly winds of the northern mid-latitudes.

As the air rises up over the mountains, it expands and cools, triggering condensation that forms clouds and causes precipitation on the windward (west facing) slopes. At the same time, the latent heat stored in the water vapor in the air is released by the condensation process, adding measurable heat to the air As the now warmer and drier air continues its eastward journey over the peaks and begins its descent into the valleys on the leeward side of the range, its temperature rises as it is compressed under the higher atmospheric pressure of the lower elevations. The fact that Death Valley lies below sea level causes even more compression of the descending air, creating a very hot and dry “rain shadow desert” in Death Valley.

Segments from the NATURE episode “Life in Death Valley” provide students with dramatic examples of the effects of the atmospheric and geologic conditions that come together to produce one of the most extreme environments on earth.

Suggested Focus Questions:

Clip 1: You Can Die Here

1. Describe the location and size of Death Valley.
2. Describe the climate of Death Valley.
3. Research the location of two other “rainshadow deserts” in the world. Why are rainshadow deserts located where they are?

Clip 2: Clouds & Currents

1. What drives the circulation of air in Death Valley?
2. Why is the air that comes down the mountainsides into the valley so dry?
3. Air at a particular elevation on the windward side of the mountains is cooler than air at the same elevation on the leeward side. How can that difference be explained?

Clip 3: Runnin’ with the Devil

1. What are the threats to human survival in Death Valley?
2. What preparations can people take to ensure their survival in Death Valley?
3. What adaptations might help plants and animals that live in Death Valley to survive?

Downloadable QuickTime versions of the video segments:
(Note: To download a video, right-click on the video title and click “Save Link As…” or “Save Target As…”. On a Mac, press the CTRL key and simultaneously click the mouse, then save the link.)

Clip 1, “You Can Die Here.”

Clip 2, “Clouds & Currents.”

Clip 3, “Runnin’ with the Devil.”

GRADE LEVEL: 8-10

TIME ALLOTMENT: Two 45-minute class periods

OVERVIEW: Death Valley lies just to the east of the high peaks of the Sierra Nevada Mountains of central California. At 282 feet below sea level, it is the lowest point in the United States. It is also both the hottest and driest place in the United States. Death Valley is an example of a “rain shadow desert,” one of many such deserts located in the lee of high mountain ranges around the world. This lesson will help students to evaluate how the interactions of air, moisture, wind, and topography combine to create an environment of such extremes.

Utilizing a directed inquiry approach, students will discover precipitation patterns in the southwest United States. Using clips from the Nature episode “Life in Death Valley,” precipitation maps and Google Maps satellite images (or an optional Google Earth tour) students will describe the differences in precipitation on the west and east flanks of the Sierra Nevada. Through classroom discussion, students will then explore the reasons for those differences.

SUBJECT MATTER: Earth Science, Meteorology, Climate, Deserts, Rain Shadow Deserts

LEARNING OBJECTIVES:

Students will be able to:

• Read and interpret a Planetary Winds diagram
• Describe the precipitation patterns on the windward and leeward sides of mountains
• Explain the reasons for the precipitation patterns on the windward and leeward sides of mountains
• Relate knowledge about temperature and pressure to meteorological effects

STANDARDS AND CURRICULUM ALIGNMENT

National Science Education Standards

CONTENT STANDARD D: AS A RESULT OF THEIR ACTIVITIES IN GRADES 9-12, ALL STUDENTS SHOULD DEVELOP AN UNDERSTANDING OF:

ENERGY IN THE EARTH SYSTEM

• Global climate is determined by energy transfer from the sun at and near the earth’s surface. This energy transfer is influenced by dynamic processes such as cloud cover and the earth’s rotation, and static conditions such as the position of mountain ranges and oceans.

GEOCHEMICAL CYCLES

• The earth is a system containing essentially a fixed amount of each stable chemical atom or element. Each element can exist in several different chemical reservoirs. Each element on earth moves among reservoirs in the solid earth, oceans, atmosphere, and organisms as part of geochemical cycles.
• Movement of matter between reservoirs is driven by the earth’s internal and external sources of energy. These movements are often accompanied by a change in the physical and chemical properties of the matter. Carbon, for example, occurs in carbonate rocks such as limestone, in the atmosphere as carbon dioxide gas, in water as dissolved carbon dioxide, and in all organisms as complex molecules that control the chemistry of life.

New York State Regents Core Curriculum Alignments:

Physical Setting: Earth Science Core Curriculum

Mathematics, Science, and Technology

Standard 2: Information Systems
Students will access, generate, process, and transfer information, using appropriate technologies.

Key Idea 1. Information technology is used to retrieve, process, and communicate information as a tool to enhance learning

Standard 4
Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and recognize the historical development of ideas in science.

Key Idea 2. Many of the phenomena that we observe on Earth involve interactions among components of air, water, and land.

Performance Indicator 2.1c
Weather patterns become evident when weather variables are observed, measured, and recorded. These variables include air temperature, air pressure, moisture (relative humidity and dewpoint), precipitation (rain, snow, hail, sleet, etc.), wind speed and direction, and cloud cover.

Performance Indicator 2.1e
Weather variables are interrelated. Temperature and humidity affect air pressure and probability of precipitation. Air pressure gradient controls wind velocity.

Performance Indicator 2.2c
A location’s climate is influenced by latitude, proximity to large bodies of water, ocean currents, prevailing winds, vegetative cover, elevation, and mountain ranges.

Key Idea 4. Energy exists in many forms, and when these forms change energy is conserved.

MEDIA COMPONENTS:

Video

NATURE: Life in Death Valley, selected clips

Clip 1, “You Can Die Here.”

Environmental conditions of Death Valley, CA.

Clip 2, “Clouds & Currents.”

Cloud formations over the Sierra Nevada Mountains.

Clip 3, “Runnin’ with the Devil.”

Running a race in Death Valley must be done with extreme caution!

Access the streaming and downloadable video segments for this lesson at the Video Segments Page.

Web Sites

Planetary Winds Diagram
A diagram from the New York State Education Department’s Earth Science Reference Tables (ESRT).

Relief Map of California
A color-coded map from the United States Geological Survey showing terrain elevations in California.

California’s Average Annual Precipitation Map
A color-coded map from Oregon State University showing average annual rainfall in California.

MATERIALS:

For each student:

• A copy of the Planetary Winds diagram from page 14 of the Earth Science Reference Tables (ESRT)
• “Rainshadow Deserts Student Organizer “(PDF) (RTF)
• “Precipitation Student Organizer” (PDF) (RTF)
• Relief Map of California, color copy
• California’s Average Annual Precipitation Map, color copy

For each group of 3-4 students:

• “Global Deserts Student Organizer” (PDF) (RTF)

For the classroom:

• One computer with broadband internet access, connected to a LCD projector and screen.
• One overhead projector or similar digital projection device.
• Rainshadow Deserts Student Organizer – Teacher Answer Key (PDF) (RTF)
• Precipitation Student Organizer – Teacher Answer Key (PDF) (RTF)
• Optional Google Earth tour to accompany this classroom exercise: rainshadow.kmz
• Additional instructions for optional Google Earth tour. (PDF) (RTF)

PREP FOR TEACHERS

Prior to teaching this lesson, you will need to:

Preview all of the video clips and Web sites used in the lesson.

Download the video clips used in the lesson to your classroom computer, or prepare to watch them using your classroom’s Internet connection.

Bookmark the Web sites used in the lesson on each computer in your classroom. Using a social bookmarking tool such as del.icio.us or diigo (or an online bookmarking utility such as portaportal) will allow you to organize all the links in a central location.

Make copies of all print materials as outlined in the materials section. Make sure you can quickly and reliably switch the screen from the computer display to the overhead or digital projection display. If using the optional Google Earth Tour for Learning Activity One, follow these additional instructions: (PDF) (RTF).

Next: Proceed to Activities