Grade Level/Unit Number: 7th grade/Unit 3 II: Unit Title: Weather & Atmosphere
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Day 6Elaborate:Energy is transferred between the earth's surface and the atmosphere by conduction, convection, and radiation. Students may not be familiar with the terms but may be able to understand with a few real-world connections. The following is a good lead-in to convection and currents, either air or water. To help students tie in to real world situations, discuss where the coldest water in the swimming pool is always found (at the bottom). Ask students why? Because the density of cold water is greater than the density of warm water.
The bottom of the pot (the part touching the burner) will become hot. This heats the water in the bottom of the pot and since hot air/hot water rises it would then move to the top of pot of water. The bottom layer of water (now heated) will then be pushed to the water in the top. This circulation continues until the entire pot boils. This is an example of convection currents. This principal can also be applied to air. The following is a teacher demonstration that will reinforce the movement of air and or water based on its temperature difference. Materials: Baby food jar with two large diameter straws inserted through the top and sealed as shown below 1000 ml beaker filled with ice water Warm water Food coloring (blue and green work best) Place two drops of food coloring into the bottom of the baby food jar. Fill the jar with warm/hot water and cover with the altered cap. Place the baby food jar apparatus into the beaker of ice water. Have the students record what occurs and why. Demonstration diagram: 
The following terms can be for teacher review and to reinforce vocabulary for students. Later in the unit, students will create a foldable about these terms. Conduction is the process by which heat energy is transmitted through contact with close-by molecules. Some solids, such as metals, are good conductors of heat while others, such as wood, are poor conductors. Air and water are poor conductors. Since air is a poor conductor, most energy transfer by conduction occurs right at the earth's surface. At night, the ground cools and the cold ground conducts heat away from the adjacent air. During the day radiation from the sun heats the ground, which heats the air next to it by conduction. Convection transmits heat by transporting groups of molecules from place to place within a substance. Convection occurs in fluids such as water and air, which move freely. In the atmosphere, convection includes rising and sinking air masses. This distributes heat and moisture throughout the atmosphere and contributes to the development of clouds and storms. Radiation is the direct transfer of heat energy. Energy travels from the sun to the earth by electromagnetic waves. The following is an example that students can relate to, incorporating all three types of energy transfer. There are three ways to cook popcorn.
Put oil in the bottom of a pan. Cover the bottom of the pan with popcorn kernels. Place the pan on the stove and turn on the burner to medium heat. Cover the pan with a lid. Periodically shake the pan so the kernels move around in the oil. (Heat from the stove burner is transferred through the pan heating the popcorn.) This is an example of conduction. Obtain an electric popcorn popper. Place the popcorn kernels in the popper. Plug in/turn on the popper. (Hot air will transfer heat to the kernels, making them expand and pop.) This is an example of convection. Microwave a bag of microwave popcorn. (The microwave directly produces heat which is transferred to the bag. Heat is trapped in the bag and pops the popcorn.)This is an example of radiation. The activity is from: http://outreach.physics.utah.edu/labs/atmosphere/popcorn.html Discuss the following scenarios and ask students to determine if each is an example of conduction, convection, or radiation. Have signs prepared ahead of time (3 for each student) or ask students to take 3 scrap pieces of paper and label each one with a type of energy transfer. As you read the scenarios to them, give them a few seconds to answer. When you say show, students hold up the paper with their choice. Attachment 6 includes 2 diagrams to share with your class. It shows a visual of each energy transfer. Attachment 7 is a page to copy to give students so they may complete the scenario activity (cut on dotted lines). Directory: file -> view view -> Western Europe after wwii view -> Author study: paul fleischman view -> Qpa1 7ela study Guide view -> Arctic Oil/Gas Neg view -> November 1970 Approximately 150,000-500,000 deaths Bhola Cyclone Bangladesh view -> Grade Level: 6 Unit of Study: Caribbean glce view -> Citation: Duffield, Katy view -> Table of Contents Lesson # view -> Chinese Wind Energy Disad Download 1.54 Mb. Share with your friends:
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