Surface and Air Temperatures Throughout the Day

This line graph shows how the surface temperature and air temperature values change over the course of 24 hours. Surface temperatures vary more than air temperatures during the day, but they both are fairly similar at night.

Mini Lesson

1. Direct students to observe the line graph showing the day vs night variation of Surface and Air Temperature values.
2. Describe the variables to student:
• Surface Temperature: This quantity represents the temperature of the first few centimeters at the top of the surface.

• Air Temperature: This quantity refers to the temperature of the air about 2 meters above the surface.

3. Instruct students to observe that there are four different line graphs.

4. Ask students to identify what the axes represent:

• The X-axis - The x-axis shows land use areas.  Ask students to think about what you will find in the different areas (e.g., When you visit a big city, you won’t see many plants. Instead, you’ll see sidewalks, streets, parking lots and tall buildings. These structures are usually made up of materials such as cement, asphalt, brick, glass, steel and dark roofs). As you head to rural areas, you will probably find that most of the region is covered with plants (grass, trees, and farmland covered with crops).

• The Y-axis - The y-axis represents temperature.  It should be the same for all four variables. There is no scale because this graphic is a generic representation and doesn't represent any particular geographic region, over a particular time.  It shows the general pattern of these changes over a 24-hour cycle over a variety of land-use areas.

5. Ask students to work with their partner to identify and discuss the following questions/tasks:
• What do you see? Identify any trends and differences you see in the graph. Pay special attention to the trends in surface and air temperature at each time of day as well as the difference in surface temperature between the day and night.  [Answers may vary.  Answers may include: Surface temperatures vary more than air temperatures during the day, but they both are fairly similar at night. The temperatures generally increase from the outskirts of the urban areas as you move towards the city center.]

• What do these trends and differences mean?  [City-related materials such as black roofs, roads, etc. cause urban areas to absorb and retain heat. Also, the heat produced by automobiles, factories, and homes may also contribute to the higher temperatures.]

• What is something you would like to know about this graph? Come up with a research question you would like to know the answer to. [Answers will vary.]