Layers of the atmosphere

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Typical top of the troposphere (rounded)

   Place	Height (km)
   Poles	8
   Mid-latitudes	11
   Equator	17

2. 1.

   Bo reads the table. Which explanation fits the troposphere being deepest at the equator?

   • The ozone layer at the equator pushes the troposphere upward
   • The equator has less water vapor, so the troposphere is taller
   • Strong heating at the equator lets air rise higher before it cools to match its surroundings
   • Gravity is weaker at the equator, so air spreads higher

3. Layer boundaries (about, NOAA)

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

4. 2.

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

   • The mesosphere, 85 km thick
   • The stratosphere, 39 km thick
   • The stratosphere, 50 km thick
   • The mesosphere, 35 km thick
5. 3.

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

6. US Standard Atmosphere

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

7. 4.

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

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

8. A balloon sounding (example data)

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

9. 5.

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

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

10. US Standard Atmosphere

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

11. 6.

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

    • Ozone is most plentiful here, so the air absorbs less sunlight and cools
    • The ground heats this layer, and the heat fades with distance
    • Pressure rises with height here, which cools the air
    • Little ozone is left to absorb ultraviolet light, so the air loses heat and cools
12. 7.

    Argon is 0.93% of dry air. Sea-level pressure is 1,013.25 hPa. Partial pressure of a gas = share × pressure. Ren finds the pressure of argon alone at sea level. What is it?

    • About 9.4 hPa
    • About 0.94 hPa
    • About 790 hPa
    • About 94 hPa
13. 8.

    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 0.014%
    • About 50%
    • About 33%
    • About 140%
14. 9.

    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?

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

15. US Standard Atmosphere

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

16. 10.

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