Layers of the atmosphere

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Two layers (typical values, rounded)

   Layer	Air temperature	Air density (kg/m³)
   Troposphere at the ground	15 °C	1.2
   Thermosphere at 400 km	1,000 °C or more	0.000000000003

2. 1.

   A student says a satellite at 1,000 °C or more in the thermosphere must burn up. Noah checks the table. Which reply is best?

   • No: the thermosphere is cold, so its air temperature is below 15 °C
   • No: with so few molecules per cubic meter, very little heat reaches the satellite despite the temperature
   • Yes: the thermosphere has more molecules than the ground, so it carries more heat
   • Yes: temperature is heat, so 1,000 °C will heat anything it touches

3. Card

   At its peak near 30 to 35 km, ozone is about 8 molecules in every million (8 ppm), or 0.0008% of the air. Ozone absorbs harmful ultraviolet light.

4. 2.

   A student says a gas making up under 0.001% of the air cannot matter. Bo replies using ozone. Which reply is best?

   • No: ozone is only about 8 ppm, yet it absorbs the Sun's harmful ultraviolet
   • Yes: ozone matters only because it is as plentiful as argon
   • No: ozone is 8% of the air, so it absorbs a large share of sunlight
   • Yes: a share that small cannot absorb a measurable amount of the Sun's light

5. US Standard Atmosphere

   Height (km)	Temperature (°C)	Pressure (hPa)
   11	-56.5	226.32
   32	-44.5	8.68

6. 3.

   A student says temperature falls steadily with height, so 32 km must be colder than 11 km. Luz checks the table. Which reply is best?

   • Yes: temperature falls at each height shown, as it does in the troposphere
   • No: 32 km is 12 °C warmer than 11 km, since ozone heats the stratosphere
   • No: 32 km is 12 °C warmer than 11 km, since the ground heats the stratosphere
   • Yes: pressure falls from 226 hPa to 9 hPa, so the air at 32 km is colder

7. Card

   Pressure is 1,013.25 hPa at the ground and 8.68 hPa at 32 km, so more than 99% of the air lies below 32 km. Scale: 1 km is drawn as 1 mm.

8. 4.

   Jun draws Earth to this scale. How thick is the skin that holds more than 99% of the air?

   • About 320 mm, as thick as a large book
   • About 3.2 mm, thinner than a coat of paint
   • About 32 mm, a thin skin around a ball over 6 m wide
   • About 11 mm, the top of the troposphere, thicker than a coat of paint

9. Ozone and temperature (ozone is example data)

   Height (km)	Ozone (ppm)	Temperature (°C)
   20	3	-56.5
   32	8	-44.5
   47	3	-2.5

10. 5.

    A student says the air should be warmest where ozone peaks. Pia checks the table. Which reply is best?

    • No: ozone peaks at 32 km, yet the air is warmest at 47 km, where sunlight is stronger
    • No: ozone has no link to temperature, since 20 km and 47 km have equal ozone
    • Yes: the warmest height is 20 km, which has the least ozone
    • Yes: ozone peaks at 32 km, so 32 km is the warmest height at −44.5 °C
11. 6.

    Two explanations: the stratosphere is heated from above by sunlight, or from below by the ground. Which observation best decides between them, by Ren?

    • Ozone is found in the stratosphere at each latitude, as shown on any map of the world
    • The troposphere cools with height at each latitude, as each balloon sounding shows
    • The stratosphere over a pole cools sharply in winter, when no sunlight reaches it
    • The stratosphere is colder than the ground in the same place, at any season of the year

12. Two carbon dioxide records (example data)

    Site	Average (ppm)	Range in one day (ppm)
    City rooftop	470	380 to 620
    Remote mountain	421	420 to 422

13. 7.

    Tala wants a record that represents the whole atmosphere. Which record is better evidence, and why?

    • The remote mountain: well-mixed air varies by 2 ppm in a day, against 240 ppm in the city
    • The city rooftop: a wide daily range of 380 to 620 ppm gives more information
    • The city rooftop: its higher average of 470 ppm shows how much carbon dioxide there is
    • Neither: carbon dioxide at one site cannot tell anything about the atmosphere

14. US Standard Atmosphere

    Height (km)	Temperature (°C)	Pressure (hPa)
    0	15.0	1,013.25
    11	-56.5	226.32
    20	-56.5	54.75
    32	-44.5	8.68
    47	-2.5	1.11
    51	-2.5	0.67
    71	-58.5	0.04

15. 8.

    Zee reads all seven rows. Which summary of temperature with height fits the table?

    • It falls to 11 km and then rises steadily to 71 km
    • It falls to 11 km, holds, rises to 47 km, holds, then falls to 71 km
    • It falls steadily with height, as it does in the troposphere, up to the top
    • It rises steadily with height, since each layer is nearer the Sun than the last
16. 9.

    Ari compares the pressure column with the temperature column. Which summary fits the table?

    • Both fall at every step, so colder air always means lower pressure
    • Neither one changes much between 11 km and 32 km
    • Pressure falls at every step, but temperature falls, holds and rises, so the two do not move together
    • Pressure follows temperature, falling where it falls and rising where it rises
17. 10.

    Milo turns pressure into shares of the air. Which summary of where the air lies fits the table?

    • About 78% lies in the troposphere, about 22% in the stratosphere, and about 1% above 51 km
    • About 22% lies in the troposphere, about 78% in the stratosphere, and under 0.1% above 51 km
    • About 50% lies in the troposphere, about 50% in the stratosphere, and nothing above 51 km
    • About 78% lies in the troposphere, about 22% in the stratosphere, and under 0.1% above 51 km