The Composition of the Atmosphere Flashcards
What is the atmosphere?
The envelope of gases surrounding the earth or another planet
Held in place by gravity
What gases make up the atmosphere?
78% nitrogen
21% oxygen
1% argon
other gases include carbon dioxide, methane, nitrous oxide, ozone
Natural processes that contribute to atmospheric gases
photosynthesis
respiration
decomposition
combustion
What does dynamic equilibrium mean?
changes that happen in balance
What happens during the process of photosynthesis?
take in CO2 and water
produce glucose and oxygen
Where are CO2 levels highest throughout the year?
December - northern hemisphere
June - southern hemisphere
during winter due to reduced photosynthesis
When do plants respire?
all of the time
When is the rate of photosynthesis greatest?
summer - greatest amount of sunlight, high temperatures
When is the rate of respiration greater than the rate of photosynthesis?
winter, night
Define transpiration
the process by which plants give off water vapour through the stomata in their leaves
What are the four layers of the atmosphere?
troposphere
stratosphere
mesosphere
thermosphere
Distance of troposphere from earth’s surface
0-10km
Distance of stratosphere from earth’s surface
10-50km
Distance of mesosphere from earth’s surface
50-80km
Distance of thermosphere from earth’s surface
80-300km
Boundary between troposphere and stratosphere
tropopause
Boundary between stratosphere and mesosphere
stratopause
Boundary between mesosphere and thermosphere
mesopause
Why are there temperature variations between the four layers?
variations in absorption of solar energy
What happens to temperature in the troposphere as altitude increases?
temperature decreases
What happens to temperature in the stratosphere as altitude increases?
temperature increases
What causes the increase in temperature in the stratosphere?
ozone layer
absorbs UV radiation from the sun
What does ozone protect us from?
most of the Sun’s UV radiation
can cause cancer, genetic mutations, sunburn
What happens to temperature in the mesosphere as altitude increases?
temperature decreases - does not absorb solar radiation
What happens to temperature in the thermosphere as altitude increases?
temperature increase
What causes the temperature to decrease with height in the troposphere?
energy that is re-radiated by the earth dissipates as altitude increases
How does air density change with altitude?
decrease - weaker gravity
How does air pressure change with altitude?
decrease - fewer air molecules
How does the atmosphere support life?
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
