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Winds
And
Weather

by Jonas Ramoth and Sidney Stephens

Activity Series 4- Heating the Earth*

 Summary In this series of activities, students explore how the angle of sunlight affects the Earth's temperature and seasons and then apply this understanding to their local situation. Background We live on a moving planet that is heated by the sun. The Earth moves in two important ways: (1) it rotates on its axis causing day and night in a 24 hour cycle and: (2) it revolves (or orbits) around the sun in a 365 day annual cycle creating the seasons. Each season has its distinctive temperature range which influences weather patterns. For example, in summer when the northern hemisphere is tilted toward the sun, daylight increases to 13-24 hours and the rays of sunlight shine almost straight down, heating the ground much more effectively than in winter when the rays hit Earth at a shallow angle. Together, longer daylight hours and more direct heating of the Earth create characteristically warm summer days. In winter the opposite is true. This heating of the Earth drives both winds and the water cycle.

 Activity 4a Materials Per Group: 5cm diameter Styrofoam ball, turkey skewer, 5cm x 5cm square of wood in which a hole has been drilled at a 24° angle, socket-type light fixture Procedure Gear-up 1. Ask each student to write down on a piece of paper what they think causes seasons. After individuals have recorded their ideas, have them share their ideas with members of their cooperative group. Record the ideas of the different groups about the cause of seasons. Check things on which they all agree and circle ideas on which they disagree. Remind the students that during the following investigations they will want to watch for data that will support or refute their ideas. During the investigations you will want to check with students to see how their concepts might be changing. Explore/ Generalize: 2. Challenge the students to set up a model of the Earth and Sun which will explain both seasons and the changing day length. Tell students that the Earth is tilted on its axis approximately 24 ° from vertical. Give each cooperating group a 5 cm diameter Styrofoam ball that will be used as a model for the Earth. Have the students insert a wooden turkey skewer through the center of the ball to mark the model Earth's axis. Provide each cooperating group with a 5 x 5 cm square of wood in which a hole the size of the diameter of the turkey skewer has been drilled. The hole should be drilled at a 24 ° angle. Have the students put one end of the turkey skewer into the hole. This will keep the model Earth at the correct tilt. 3. Tell the students that as the Earth revolves around the Sun, the Earth's northern axis is always pointed toward the Polaris, the North Star. Locate a spot on the ceiling that will serve as a model North Star. As the students' construct their model to demonstrate seasons, remind them to keep the North Pole of the model Earth always pointing towards North Star. 4. Provide each cooperating group with a socket type light fixture that they will use to simulate the model Sun. Remind the students as they are working on their models, to rotate the model Earth on the turkey skewer to see what impact the Earth's position to the Sun has on day length. (For example, when the model Earth's Northern Hemisphere is tilted toward the model Sun, the North Pole is illuminated during an entire rotation of the Earth.) Remind the students to look at the position in which the direct rays of light from the Sun strike the Northern Hemisphere. At what position do the rays from the Sun strike the Northern Hemisphere at the greatest angle? How might the angle at which light strikes a region affect the temperature of that region?

 Activity 4b Materials Per Group - black construction paper, 3 thermometers, books Procedure Gear-up 1. Ask how the angle of sunlight affects the Earth's temperature? At what time of day is the heat from the Sun's rays the most intense? (At local solar noon or the time when the sun appears to have reached its highest point in the sky during the day. It occurs halfway between sunrise and sunset.) What is your explanation for this observation? During what time of day does the Sun appear to be directly over head? At what time of day will rays from the Sun strike us the most directly? At what times during the day will the rays from the Sun strike us at a slant? (When light rays strike head-on the heat intensity is much greater than when the light rays strike at a slant and the light rays are dispersed over a bigger area spreading out the warmth) Explore 2. Have student groups make three black envelopes by folding pieces of black construction paper into thirds, folding up the bottom end and taping closed. Insert a thermometer into each black envelope. On a sunny window sill prop up the envelope clad thermometers at different angles. Thermometer One: Using a book, prop an envelope-covered thermometer against the book so that the thermometer faces away from the sun. Sun light should barely touch the flat part of the envelope. Thermometer Two: Place the second thermometer in its black envelope flat on top of a book. The sun should strike the envelope at an angle. Thermometer Three: Prop the third thermometer in its envelope against two books. Adjust the envelope so the sun's rays strike it directly. At the end of five minutes read the temperature on all three thermometers. Generalize 3. Which registers the highest temperature? The lowest? How does the angle at which the Sun's rays strike the envelope affect the temperature reading? How would this explain why temperatures tend to be warmer around noon? How would this explain why temperatures in summer tend to be warmer than temperatures in winter? How would this explain winter temperatures in the far north are so cold?
 Activity 4c: Materials Per Group: hollow cardboard tube, a flashlight and a piece of cardboard Procedure Gear-up: 1. Ask students how much more area does light at a slant cover than head-on rays? Explore 2. Give each cooperating group a hollow cardboard tube, a flashlight and a piece of cardboard. 3. Insert the flashlight into one end of the tube. Hold the tube about four inches directly above the cardboard. Turn on the flash light and trace around the illuminated area on the cardboard. Now, still hold the tube four inches from the cardboard but slant the tube so that the light rays strike the cardboard at an angle. Trace around the illuminated area made by the slanted light rays. Generalize 4. The same amount of light passed through the tube. In which case did the light cover the bigger area? If the same amount of light is spread out more over a bigger area, how will this affect the heat absorbed from the light? Apply/Assess: 5. During what time of day are rays from the Sun spread out the most? The least? During what time of the day light hours is the Earth's surface usually the warmest? Usually the coolest?

6. In what season do the rays from the Sun hit the Earth the most directly? At the greatest slant? What affect does this have on the Earth's temperature at these times?

7. Around June 21, what part of the Earth gets sunlight head on? Around December 21 ? How does the angle at which light strikes the Northern Hemisphere compare on March 21 and September 21? How is this likely to affect the temperature of the Northern Hemisphere at these times of year?

* Adapted from Barr, B. (1994)

Standards

Section I - Observing Locally

Section II - Understanding Wind

Section III - Connecting Globally

Appendix A - Selawik Weather Information from Jonas Ramoth

Appendix B - Assessment

Appendix C - Weather Resource List

Appendix D - Interdisciplinary Integration

 Whouy Sze Kuinalth "Teaching Our Many Grandchildren" Tauhna Cauyalitahtug (To Make a Drum) Math Story Problems St. Lawrence Island Rain Parka Winds and Weather Willow Driftwood Snowshoes Moose Plants of the Tundra Animal Classification for Yup'ik Region Rabbit Snaring The Right Tool for the Job Fishing Tools and Technology Blackfish Family Tree Medicinal Plants of the Kodiak Alutiiq Archipelago Beaver in Interior Alaska Digging and Preparing Spruce Roots Moose in Interior Alaska Birds Around the Village

Handbook for Culturally Responsive Science Curriculum by Sidney Stephens
Excerpt: "The information and insights contained in this document will be of interest to anyone involved in bringing local knowledge to bear in school curriculum. Drawing upon the efforts of many people over a period of several years, Sidney Stephens has managed to distill and synthesize the critical ingredients for making the teaching of science relevant and meaningful in culturally adaptable ways."

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