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?

   • Troposphere now, stratosphere next
   • Stratosphere now, troposphere next
   • Mesosphere now, thermosphere next
   • Stratosphere now, mesosphere next

3. US Standard Atmosphere

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

4. 2.

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

   • It falls 54 °C
   • It rises 59 °C
   • It stays the same
   • It rises 54 °C
5. 3.

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

   • 20 km, in the stratosphere
   • 11 km, in the troposphere
   • 71 km, in the thermosphere
   • 71 km, in the mesosphere
6. 4.

   Temperature rises with height through the stratosphere. What does Milo say heats the air there?

   • The layer is closer to the Sun than the layers below it
   • Clouds in the stratosphere release heat as they form
   • Warm air rising from the ground heats it directly
   • Ozone absorbs ultraviolet light and warms the air

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 meteor glowing at 80 km
   • The space station orbiting at 400 km
   • The weather balloon bursting at 30 km
   • The jet airliner cruising at 11 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 troposphere, where ozone peaks near 10 km
    • The thermosphere, where ozone peaks near 25 km
    • The mesosphere, where ozone peaks near 40 km
    • The stratosphere, where ozone peaks near 25 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
    • 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
    • Ozone near 11 km heats the air and drives the storms

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 1%, mostly argon
    • About 0.04%, mostly carbon dioxide
    • About 21%, mostly oxygen
    • 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 226 hPa, because the whole of the air at 11 km is oxygen
    • 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 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?

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