The Composition of the Atmosphere

Question 1

What is the atmosphere?

Answer 1

The envelope of gases surrounding the earth or another planet

Held in place by gravity

Question 2

What gases make up the atmosphere?

Answer 2

78% nitrogen
21% oxygen
1% argon

other gases include carbon dioxide, methane, nitrous oxide, ozone

Question 3

Natural processes that contribute to atmospheric gases

Answer 3

photosynthesis
respiration
decomposition
combustion

Question 4

What does dynamic equilibrium mean?

Answer 4

changes that happen in balance

Question 5

What happens during the process of photosynthesis?

Answer 5

take in CO2 and water
produce glucose and oxygen

Question 6

Where are CO2 levels highest throughout the year?

Answer 6

December - northern hemisphere
June - southern hemisphere

during winter due to reduced photosynthesis

Question 7

When do plants respire?

Answer 7

all of the time

Question 8

When is the rate of photosynthesis greatest?

Answer 8

summer - greatest amount of sunlight, high temperatures

Question 9

When is the rate of respiration greater than the rate of photosynthesis?

Answer 9

winter, night

Question 10

Define transpiration

Answer 10

the process by which plants give off water vapour through the stomata in their leaves

Question 11

What are the four layers of the atmosphere?

Answer 11

troposphere
stratosphere
mesosphere
thermosphere

Question 12

Distance of troposphere from earth’s surface

Answer 12

0-10km

Question 13

Distance of stratosphere from earth’s surface

Answer 13

10-50km

Question 14

Distance of mesosphere from earth’s surface

Answer 14

50-80km

Question 15

Distance of thermosphere from earth’s surface

Answer 15

80-300km

Question 16

Boundary between troposphere and stratosphere

Answer 16

tropopause

Question 17

Boundary between stratosphere and mesosphere

Answer 17

stratopause

Question 18

Boundary between mesosphere and thermosphere

Answer 18

mesopause

Question 19

Why are there temperature variations between the four layers?

Answer 19

variations in absorption of solar energy

Question 20

What happens to temperature in the troposphere as altitude increases?

Answer 20

temperature decreases

Question 21

What happens to temperature in the stratosphere as altitude increases?

Answer 21

temperature increases

Question 22

What causes the increase in temperature in the stratosphere?

Answer 22

ozone layer

absorbs UV radiation from the sun

Question 23

What does ozone protect us from?

Answer 23

most of the Sun’s UV radiation

can cause cancer, genetic mutations, sunburn

Question 24

What happens to temperature in the mesosphere as altitude increases?

Answer 24

temperature decreases - does not absorb solar radiation

Question 25

What happens to temperature in the thermosphere as altitude increases?

Answer 25

temperature increase

Question 26

What causes the temperature to decrease with height in the troposphere?

Answer 26

energy that is re-radiated by the earth dissipates as altitude increases

Question 27

How does air density change with altitude?

Answer 27

decrease - weaker gravity

Question 28

How does air pressure change with altitude?

Answer 28

decrease - fewer air molecules

Question 29

How does the atmosphere support life?

Answer 29

pressure for liquid water
keeps temperature habitable
drives air movement and weather patterns
creates ocean currents (via wind)
protects us from UV
CO2 for photosynthesis