Layers of the atmosphere

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Layer bases (about, NOAA)

   Layer	Starts at (km)
   Troposphere	0
   Stratosphere	11
   Mesosphere	50
   Thermosphere	85

2. 1.

   A balloon rises to 30 km. Ari reads the table. Which layer is it in, and which comes next?

   • Stratosphere now, mesosphere next
   • Stratosphere now, troposphere next
   • Troposphere now, stratosphere next
   • Mesosphere now, thermosphere next
3. 2.

   Kira climbs from the ground to 100 km. The layers change at about 11, 50 and 85 km. How many boundaries are crossed?

   • Three, at about 11, 50 and 85 km
   • Three, at about 11, 30 and 60 km
   • Two, at about 11 and 85 km
   • Four, at about 11, 50, 85 and 100 km

4. US Standard Atmosphere

   Height (km)	Temperature (°C)	Pressure (hPa)
   20	-56.5	54.75
   32	-44.5	8.68
   47	-2.5	1.11

5. 3.

   Jun reads the table from 20 km up to 47 km. How does the temperature change?

   • It rises 59 °C
   • It rises 54 °C
   • It stays the same
   • It falls 54 °C
6. 4.

   Luz scans all seven rows. At which height is the air coldest, and in which layer?

   • 71 km, in the thermosphere
   • 71 km, in the mesosphere
   • 11 km, in the troposphere
   • 20 km, in the stratosphere

7. Four events and their heights (example)

   Event	Height (km)
   Jet airliner cruising	11
   Weather balloon bursting	30
   Meteor glowing	80
   Space station orbiting	400

8. 5.

   Noah sorts the events by layer. Which event happens in the mesosphere (about 50 to 85 km)?

   • The weather balloon bursting at 30 km
   • The jet airliner cruising at 11 km
   • The space station orbiting at 400 km
   • The meteor glowing at 80 km

9. Ozone by height (example data)

   Height (km)	Ozone (ppm)
   10	0.3
   25	7
   40	5

10. 6.

    Pia finds where ozone is greatest. Which layer holds the most ozone?

    • The stratosphere, where ozone peaks near 25 km
    • The troposphere, where ozone peaks near 10 km
    • The thermosphere, where ozone peaks near 25 km
    • The mesosphere, where ozone peaks near 40 km

11. US Standard Atmosphere

    Height (km)	Temperature (°C)	Pressure (hPa)
    0	15.0	1,013.25
    11	-56.5	226.32

12. 7.

    Temperature falls from 15 °C to −56.5 °C in the first 11 km. Ren explains why storms stay in that layer. Which reason fits?

    • Warm air near the ground rises and mixes with the colder air above it
    • Ozone near 11 km heats the air and drives the storms
    • Warm air above the ground sinks and mixes with the colder air below it
    • Pressure rises with height, which pushes clouds back toward the ground

13. Dry air by volume (NOAA)

    Gas	Share (%)
    Nitrogen	78.08
    Oxygen	20.95
    Argon	0.93
    Carbon dioxide	0.04

14. 8.

    Tala adds up nitrogen and oxygen. About what share of dry air is neither one?

    • About 21%, mostly oxygen
    • About 0.04%, mostly carbon dioxide
    • About 1%, mostly argon
    • About 22%, mostly argon

15. Use this

    Oxygen is 20.95% of dry air at every height shown. Pressure at 11 km is 226.32 hPa. Partial pressure of oxygen = share × pressure.

16. 9.

    Zee works out how much of the pressure at 11 km is oxygen. What is it?

    • About 4.7 hPa, because the share drops to 2.1% at 11 km
    • About 212 hPa, because 21% of the ground pressure is still there
    • About 226 hPa, because the whole of the air at 11 km is oxygen
    • About 47 hPa, because the share stays near 21% while the pressure falls
17. 10.

    Carbon dioxide is 420 parts per million (ppm) of air. What percent does Esme say that is?

    • 4.2%
    • 0.42%
    • 0.0042%
    • 0.042%