Sun Energy Transformations

OVERVIEW

In this activity, students investigate how most of the Sun’s energy comes to us as light but we experience it as heat. Students will learn that this is due to an energy transformation. During the activity, they will measure various surface temperatures in sun and shade using infrared thermometers.  

MATERIALS

• Dark metal pans (2)

• Infrared Thermometers (one for each station plus one for demonstration)

• Small colored flags 

• Dark blue or black construction paper (2 sheets)

• White construction paper (2 sheets)

• Surface Temperature Investigation - Data sheet

• Blank sheets of paper (for drawings)

• Writing utensils

PREPARATION

This activity is best done on a sunny day.

• Set the dark pans outside—one in the sun, one in the shade—an hour or more before the activity. Ensure that the pans in the sun will remain in the sun for the complete time before the activity.

• Establish the temperature-taking stations listed below (choose all or some, depending on available time and space.) Identify the temperature-taking stations with the flags. You can also substitute surface types common to your area (sand, natural versus manicured.) 

  • Grass - sun and shade

  • Sidewalk or light colored pavement - sun and shade. 

  • Asphalt or dark colored pavement - sun and shade.

  • Blue sheet - sun and shade

  • White sheet - sun and shade

• Set an infrared thermometer at each station to allow it to acclimate to temperature.

• Prepare copies of the Surface Temperature Investigation - Data sheet for distribution.

ACTIVITY STEPS

ENGAGE 

Bring students outside and walk over to see and touch both dark pans—both in the sun and in the shade. Ask them to make observations about the pans. What is different, what is the same? (The salient variable is the surface temperature or feel of the pans. The pan in the sun will be hotter than the pan in the shade.)

Have students work in groups of two or three to draw a picture of what is happening to the pans. (Note: drawing a picture is a type of model making). Students’ pictures should show the pans, sun, source of shade, and the variation in the feel of the temperature (hotter, cooler).  Ask students to label the different parts of the drawing.

EXPLORE

• Back in the large group, ask students to show their drawings. Be sure to note that the surface of the items is a place to measure temperature.

• Let students know that this heat is measurable with a special kind of thermometer called an infrared thermometer. Show students the thermometer. This thermometer measures the temperature of the surface where the radiant heat is happening. Make sure students understand that this surface temperature is different from an internal temperature. Ask students if they know what a human’s standard internal temperature is. (98.6°F/37°C.) 

• Ask students to brainstorm a list of factors that might affect a surface temperature. ( Surface type, surface color, surface size, cloud cover, intensity of sun’s rays, length of day)

• Tell them that they are going to be surface temperature scientists and explore the temperatures of different surfaces outside.

• Hand out the data sheet and review the sites. 

• Demonstrate the way to hold a thermometer (straight out, chest high). Explain if they hold the thermometer too low, they risk including the temperature of their feet in the reading. However, they should hold the thermometer low over the construction paper or else the temperature will include the surrounding surface. Give other safety instructions and directions related to your particular site.

• Introduce the data collection sheet. Tell students that they are to write the surface color and temperature of each surface type and location. 

• Allow students to work in small groups to go collect data. Circulate and verify that all students are getting an opportunity to use the thermometer and are recording the data.

EXPLAIN

• After the students have recorded the data, call them back together and have them identify their highest temperature and lowest temperature and where the temperatures were taken.

• Use the High and Low Temperature - Data Chart to record the students’ high and low temp findings, by groups.

• Analyze the data. How you analyze the data depends mainly on the grade level of students. 

• Using the data from the High and Low Temperature - Data Chart, ask:

  • Where are the highest temperatures? The lowest? 

  • Did the groups find the same or very similar temperatures? 

  • What kinds of relationships can you determine between sun and shade sites? Surface color? 

  • How do sites in the sun compare with sites in the shade? Are the hottest sites in the sun also the hottest in the shade? 

  • What about light covered surfaces like cement or sand in the sun compared to a surface like grass? (Plant transpiration evaporatively cools plants while cement and sand have no such cooling mechanism.) 

Wrap up

• Have students turn and talk about what they just did and share it with the whole group.

APPLY

• Ask students to apply their findings to their community. Younger students can discuss playground landscaping. Older students can discuss the pros and cons of different types of landscaping, green roofs, development, and green space. Consider how these surfaces function in all the seasons.

STANDARDS

Science 

4-PS3-2 Make observations to provide evidence for how energy can be transferred from place to place by sound, light, heat, and electric currents. (SEP: 3; DCI: PS3.A, PS3.B; CCC: Energy/Matter) 

4-PS3-4 Design, test, and refine a device that converts energy from one form to another.* (SEP: 6; DCI: PS3.B, PS3.D, ETS1.A ; CCC: Energy/Matter)

Crosscutting Concepts

Energy and Matter: Energy can be transferred in various ways and between objects.

Disciplinary Core Ideas

PS3.A Definitions of Energy

Energy can be moved from place to place by moving objects or through sound, light, or electric currents.

PS3.B: Conservation of Energy and EnergyTransfer

Energy is present whenever there are moving objects, sound, light, or heat. When objects collide, energy can be transferred from one object to another, thereby changing their motion. In such collisions, some energy is typically also transferred to the surrounding air; as a result, the air gets heated and sound is produced.

Light also transfers energy from place to place.

Energy can also be transferred from place to place by electric currents, which can then be used locally to produce motion, sound, heat, or light. The currents may have been produced to begin with by transforming the energy of motion into electrical energy.

BACKGROUND

The Sun generates energy, which is transferred through space to the Earth's atmosphere and surface. Some of this energy warms the atmosphere and surface as heat. 

Radiation: Most of the energy coming from the sun is absorbed by the atmosphere and never reaches the Earth. That which reaches the Earth's surface is radiated back into the atmosphere to become heat energy. Dark colored objects, such as asphalt, absorb radiant energy faster than light colored objects. However, they also radiate their energy faster than lighter colored objects. (The variations in how Earth's surface absorbs heat from the Sun is called differential heating.)

Source: The Transfer of Heat Energy https://www.noaa.gov/jetstream/atmosphere/transfer-of-heat-energy 

Solar radiation that is not absorbed or reflected by the atmosphere (for example by clouds) reaches the surface of the Earth. The Earth absorbs most of the energy reaching its surface; a small fraction is reflected. In total, approximately 70% of incoming radiation is absorbed by the atmosphere and the Earth’s surface while around 30% is reflected back to space and does not heat the surface. The Earth radiates energy at wavelengths much longer than the Sun because it is colder. 

Source: The Sun’s Impact on the Earth https://wmo.int/suns-impact-earth#:~:text=In%20total%20approximately%2070%25%20of,Sun%20because%20it%20is%20colder.