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Explore how sunlight absorption impacts Earth's temperature through experiments and key concepts. Discover the importance of radiant energy, absorption, reflection, and the heating of Earth's surface.
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Question of the Day….1-13-14 • 1. Does the absorption of sunlight lower or increase Earth’s temperature? • 2. How does solar energy reach Earth? • 3. Why should you wear dark clothing in the winter, and light clothing in the summer, if you work outdoors?
Modeling the Absorption of Light… • Hypothesize: Which color will be the hottest? • 1. Place an aluminum pan under a light whose light is pointed downward. • 2. Place two different colors of construction paper into the pan. One color should be dark, the other a light color. • 3. Insert a thermometer on top of each piece of paper. Record the temperature of each. • 4. Let the papers sit under the lamp for five minutes. • How does the temperature change? • Why is one temperature higher than the other?
Key Terms • Radiant Energy: energy given off by the Sun that can travel through empty space. • Radiation: movement of the Sun’s energy through empty space. • Absorb: To take in • Reflect: To bounce back
What kind of energy is sunlight? • Have you ever walked barefoot across a sidewalk on a sunny day? Did your foot feel the warmth of the hot pavement? • The sidewalk was heated as it absorbed the Sun’s energy. • Sunlight is an example of radiant energy. Your foot burned due to Conduction.
Radiation • When energy is absorbed by a surface, the surface becomes heated. This is why you are able to feel the sun’s rays on your skin when you stand in the sun. • Your skin absorbs the radiation, causing your skin’s molecules to move a little faster. • RADIATION IS THE TRANSFER OF ENERGY AS ELECTROMAGNETIC WAVES!
Absorption of Energy • Dark surfaces absorb or take in light. • When sunlight is absorbed, it is usually changed into heat. • Dark colored objects become hotter than light colored objects. • Light colored objects reflect, or bounce back sunlight. They are cooler.
Hypothesize… • Which do you think will absorb more heat from the sun, land or water? Land
Decide whether each item listed will absorb or reflect radiant energy. Write A for absorb or R for reflect in the space provided. • 1. cream-colored sweater • 2. black suit • 3. concrete sidewalk • 4. white shirt • 5. tar-covered street • 6. dark green tent
Energy from the Sun… • Only a small part of the Sun’s energy reaches Earth. • Some of the Sun’s energy is absorbed by the atmosphere. • Clouds, dust particles and water droplets in the atmosphere reflect some of the Sun’s energy. • The energy that is reflected goes back into space.
Energy from the Sun… • Some of the energy that passes through Earth’s atmosphere is absorbed or taken in by Earth’s surface. This energy is changed into heat. As a result, Earth becomes warmer. **Create a graphic organizer showing how Earth’s Surface is heated. Use the diagram on the next slide.
Do you Remember? • Light is a type of ________. • The Sun’s energy reaches Earth by __________. • When light is __________, it turns into heat. • Clouds, ________ _________ and water droplets can reflect, or absorb radiant energy. • Predict: If there were no wind, would it be cooler on a sunny day or a cloudy day?