The Atmosphere Flashcards
(60 cards)
What is the atmosphere?
Thin layer of gases surrounding the Earth, held in place by gravity
Why is the atmosphere essential to life on earth?
provides life support systems
- absorption of EM radiation from Sun
- gas resources for natural processes
- heat distribution
- delays escape of infrared energy
- creates ocean currents
- water vapour transport
What is the composition of gases in the atmosphere?
Nitrogen 78%
Oxygen 21%
Carbon dioxide 0.04%
Rare gases 1%
Methane 0.00017%
Water Vapour up to 4%
Ozone 0.000007%
What are the four ‘building block’ gases in the atmosphere?
Carbon
Nitrogen
Oxygen
Hydrogen
What are greenhouse gases?
Gases that are better at absorbing infrared than the average for the atmosphere
How does the greenhouse effect work?
- Visible light passes easily through the atmosphere
- It gets absorbed the the Earth’s surface, warming it up
- Warm Earth’s surface emits infrared radiation
- Infrared cannot pass through the atmosphere as easily because it is absorbed by the greenhouse gases.
- They reemit. The cycle continues.
What are the factors controlling the natural greenhouse effect?
Solar Emissions
Greenhouse Gases
How do solar emissions affect the natural greenhouse effect?
- they are increasing very slowly
- there is a short term 11 year cycle of varying solar output
What is the natural source of:
a) nitrogen
b) methane
c) water vapour
d) oxygen
e) ozone
a) bacteria in soils
b) bacteria in soils
c) evaporation
d) photosynthetic organisms
e) stratosphere only
What is the anthropogenic source of:
a) oxygen
b) water vapour
a) hospitals and welding (possibly)
b) evaporation from power station cooling towers
How is water vapour affected by climate change?
- more released by humans does not increase max humidity unless temp increases because it will precipitate
- climate change causes temps to increase = max humidity increases
- concentration is balanced by evapotranspiration and condensation. Both controlled by temp. Changing temp changes concentration
What are the anthropogenic sources of CO2?
Burning fossil fuels and wood
Ploughing soil
Draining marshes/bogs
What are the anthropogenic sources of methane?
Anaerobic respiration by microbes in padi fields/intestines of livestock/landfill sites
Creation of fossil fuels
Release from coal mines
Leaks from natural gas fields/pipelines
What are the anthropogenic sources of nitrous oxides?
Reaction of oxygen and nitrogen at high temps (engines and power stations)
Then released by exhausts
Fertilisers
What are the anthropogenic sources of CFCs?
Aerosol propellants
Coolants in fridges
Fire extinguishers
Expanding foam plastics
Solvents
What is the anthropogenic source of tropospheric ozone?
Nitrogen dioxide breaking down with light then reacting with oxygen
What are the relative effects per molecule of:
a) CO2
b) Methane
c) Nitrous oxides
d) CFCs
e) Tropospheric ozon
a) 1
b) 25
c) 160
d) 25,000
e) 2,000
What is the importance to life of:
a) methane
b) water vapour
c) nitrogen
d) carbon dioxide
e) oxygen
f) ozone
a) source of energy for chemoautotrophs
b) hydrological cycle and insulation as a GG
c) synthesis of proteins
d) insulation as a GG and reactant for photosynthesis. synthesises lipids, carbs and proteins
e) respiration
f) absorbs harmful UV dangerous to life
What maintains the average composition of the atmosphere?
- natural processes are in balance: change only happens over a very long time
What natural processes are important to the stability of the composition of the atmosphere?
Photosynthesis
Respiration
- roughly balance each other out but rates vary over different timescales causing gas fluctuations around their mean concentration
How does the CO2 concentration change:
a) daily
b) annually
a) Early hours = more as it is dark so respiration outweighs photosynthesis
Middle of day = less as the increased light allows photosynthesis.
Later = more, gets darker…
b) January-April = respiration outweighs photosynthesis so concentrations are high
April-August = photosynthesis levels high so concentration decreases
August-December = respiration outweighs photosynthesis so concentrations are high
What is the importance of atmospheric processes being connected?
If one process is changed, other processes can change
- it means human actions can trigger a chain reaction of altering processes as a direct response to the first change
- not possible to accurately predict the impact on specific processes yet though as there is a lot to be discovered.
What are the layers of the atmosphere in ascending order?
Troposphere
Stratosphere
Mesosphere
Thermosphere
What is the structure of the atmosphere in relation to distance from the Earth?
Majority of atmosphere is near the ground
- 80% of gases are in the troposphere which is within 10km of surface
gradually gets thinner up to about 10,000km
- considered the upper limit of the atmosphere