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

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, 35 km thick
   • The stratosphere, 39 km thick
   • The mesosphere, 85 km thick
   • The stratosphere, 50 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 troposphere, at 1.8 km
   • The thermosphere, at 180 km
   • The stratosphere, at 18 km
   • The troposphere, at 11 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?

   • 32 to 47 km, about 42 °C per km
   • 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
8. 5.

   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 790 hPa
   • About 9.4 hPa
   • About 94 hPa
   • About 0.94 hPa
9. 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%
10. 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?

    • 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 air is thinner, so each breath holds fewer molecules though the share is still 21%
    • The oxygen share falls to 7% at 11 km, so each breath holds less

11. US Standard Atmosphere

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

12. 8.

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

    • About 2%, because 226 hPa is two tenths of 1,013
    • 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
13. 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 126 hPa, which is 44% too low
    • About 253 hPa, which is 12% too high
    • About 507 hPa, which is 124% too high
    • About 253 hPa, which is 12% too low
14. 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 0.364 kg/m³
    • About 0.289 kg/m³, using 273 K
    • About 0.0364 kg/m³
    • About 3.64 kg/m³