Layers of the atmosphere

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Layer boundaries (about, NOAA)

   Boundary	Height (km)
   Top of troposphere	11
   Top of stratosphere	50
   Top of mesosphere	85

2. 1.

   Jun compares layer thicknesses. Which layer is thickest, and how thick is it?

   • The stratosphere, 39 km thick
   • The stratosphere, 50 km thick
   • The mesosphere, 85 km thick
   • The mesosphere, 35 km thick
3. 2.

   A weather balloon rises at 5 m/s. The troposphere ends at about 11 km. Which layer does Luz say it is in after 1 hour?

   • The troposphere, at 1.8 km
   • The thermosphere, at 180 km
   • The troposphere, at 11 km
   • The stratosphere, at 18 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.

   Milo compares the 20–32 km and 32–47 km stretches. Which warms faster per km, and by how much?

   • 32 to 47 km, about 42 °C per km
   • 20 to 32 km, about 12 °C per km
   • 20 to 32 km, about 1.0 °C per km
   • 32 to 47 km, about 2.8 °C per km

6. A balloon sounding (example data)

   Height (km)	Temperature (°C)
   4	-10
   8	-37
   12	-57
   16	-57
   20	-55

7. 4.

   Noah looks for the tropopause, where cooling with height stops. Where is it?

   • About 4 km, where the weather seems to end
   • About 8 km, halfway up the cooling
   • About 20 km, the highest reading
   • About 12 km, where the cooling stops

8. US Standard Atmosphere

   Height (km)	Temperature (°C)	Pressure (hPa)
   47	-2.5	1.11
   51	-2.5	0.67
   71	-58.5	0.04

9. 5.

   Temperature falls from −2.5 °C at 51 km to −58.5 °C at 71 km. Which reason does Pia give?

   • The ground heats this layer, and the heat fades with distance
   • Pressure rises with height here, which cools the air
   • Ozone is most plentiful here, so the air absorbs less sunlight and cools
   • Little ozone is left to absorb ultraviolet light, so the air loses heat and cools
10. 6.

    Carbon dioxide rose from about 280 ppm before industry to about 420 ppm now. By what percent has it risen, by Tala's math?

    • About 140%
    • About 50%
    • About 0.014%
    • About 33%
11. 7.

    Oxygen is 21% of the air at the ground and at 11 km, yet a breath holds less oxygen at 11 km. Which reason does Zee give?

    • The air is thinner, so each breath holds fewer molecules though the share is still 21%
    • Oxygen sinks, leaving nitrogen on top, so there is less at 11 km
    • Planes use up the oxygen at 11 km, so each breath holds less
    • The oxygen share falls to 7% at 11 km, so each breath holds less

12. US Standard Atmosphere

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

13. 8.

    Pressure is the weight of the air above you. What share of the air lies above 11 km, by Esme's math?

    • About 22%, because 226 of the 1,013 hPa is air above 11 km
    • About 50%, because pressure halves at 11 km
    • About 78%, because 78% of the pressure is still above you
    • About 2%, because 226 hPa is two tenths of 1,013
14. 9.

    A model says pressure halves every 5.5 km. Ari tests it at 11 km against the table. What does it predict, and how does that compare?

    • About 253 hPa, which is 12% too high
    • About 126 hPa, which is 44% too low
    • About 253 hPa, which is 12% too low
    • About 507 hPa, which is 124% too high
15. 10.

    Pressure 22,632 Pa, temperature 216.65 K. Density = pressure ÷ (287 × temperature in kelvins), in kg/m³. Kira finds the density of the air at 11 km. What is it?

    • About 3.64 kg/m³
    • About 0.0364 kg/m³
    • About 0.289 kg/m³, using 273 K
    • About 0.364 kg/m³