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
   • 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
   • The equator has less water vapor, so the troposphere is taller
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 stratosphere, at 18 km
   • The troposphere, at 11 km
   • The troposphere, at 1.8 km
   • The thermosphere, at 180 km

4. A balloon sounding (example data)

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

5. 3.

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

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

6. US Standard Atmosphere

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

7. 4.

   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
   • Little ozone is left to absorb ultraviolet light, so the air loses heat and cools
   • The ground heats this layer, and the heat fades with distance
   • Pressure rises with height here, which cools the air
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 94 hPa
   • About 0.94 hPa
   • About 9.4 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 50%
   • About 140%
   • 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?

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

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 78%, because 78% of the pressure is still above you
    • About 50%, because pressure halves at 11 km
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 low
    • About 507 hPa, which is 124% too high
    • About 253 hPa, which is 12% too high
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 3.64 kg/m³
    • About 0.0364 kg/m³
    • About 0.289 kg/m³, using 273 K
    • About 0.364 kg/m³