P2 9 Atmosphere Flashcards
name the current proportion of gases in the atmosphere (4)
- nitrogen 78%
- oxygen 21%
- other 1%
-> carbon dioxide 0.035%
argon/ water vapour/ noble gases
describe the earth’s early atmosphere (+reason why)
- intense volcanic activity
- produced water vapour and gases (largely carbon dioxide, as well as methane/ ammonia/ nitrogen)
(similar to the current atmospheres of Mars+Venus)
describe how the oceans formed
- the earth’s early atmosphere contained water vapour
- which condensed as the earth began to cool
- formed rain clouds which precipitated to form oceans in basins
why did the level of CO2 in the atmosphere change when oceans formed
- CO2 dissolved in the ocean water
1. carbonates were precipitated (sank to bottom of ocean as solids) producing sediments, sedimentary rock formed - limestone (calcium carbonate)
2. algae (water plant) replaced CO2 with O2 by photosynthesis
3. dead plants / small organisms ‘locked up’ CO2 when they died+ compressed into fossil fuels / sedimentary rock - so CO2 levels decreased
describe the importance of algae in forming the current atmosphere
- algae evolved 2 billion yrs ago (+ other plants)
- replaced CO2 with O2 through photosynthesis
-> increase % of oxygen in atmosphere allowed animal life to develop - died to form fossil fuels - locked up CO2
why is there so much nitrogen in the current atmosphere (compared to early atmosphere)
- early plant species (algae) replaced CO2 with O2 through photosynthesis, then oxygen reacted with ammonia in atmosphere to form nitrogen (+water)
- nitrogen is unreactive so levels remain constant
describe ways carbon dioxide becomes ‘locked up’ (4)
- dissolved in oceans, carbonates precipitated as solids, form sedimentary rock at bottom of seabed (limestone)
- animals eat plants containing CO2, carbon used to make bones/shells, left as remains when dead, bones/shells compressed by mud/rock to form sedimentary rock (limestone)
- plants containg CO2 die, remains compressed by mud/rock, forms fossil (coal)
- algae containing CO2 die, remains compressed by mud/rock, forms fossil (crude oil / natural gas)
name the main greenhouse gases (3)
- water vapour
- methane
- carbon dioxide
how do greenhouse gases increase the earth’s temperature
- greenhouse gases allow short wavelength radiation to pass through from Sun
- earth absorbs short wavelength radiation, heat is radiated from earth as long wavelength (infrared) radiation
- some of this radiation is absorbed by greenhouse gases, so atmosphere’s temp rises
name human activities producing greenhouse gases in recent years (3)
- burning of fossil fuels for energy - releases CO2
- livestock and rice farming - methane released by animals during digestion / decomposed matter in flooded rice fields
- deforestation - fewer trees replacing CO2 in atmosphere
arguments against the idea that human activities cause global climate change (3)
- simplified models of the atmosphere don’t fully explain the theory - misleading
- speculation - media reports may only present parts of evidence
- media/opinions may be biased - eg. people from industries producing greenhouse gases will lie
describe large-scale events due to global climate change (3)
- melting ice caps - polar habitat loss - extinction
- extreme weather + change in precipitation patterns - damage to crops, interferes with animal breeding/migration patterns - food shortage, less biodiversity
- rising sea levels - due to rising sea temp + land-based ice loss - coastal flooding, marine life extinction
define carbon footprint
the total amount of greenhouse gases emitted over the full life cycle of a product/person/service/event
strategies for reducing carbon footprint
- renewable energy sources - lower emissions
-> biofuel - carbon neutral - energy-efficient appliances - conserves energy, reduces emissions
- taxing emissions, companies don’t pay if they plant trees instead
- carbon capture+storage - CO2 released by industry/energy production is stored underground
- recycling - conservation of natural resources
- reduce consumption eg. walking over driving
difficulties with reducing carbon footprint (3)
- countries rely on fossil fuels for profit
- renewable energy sources are expensive+ unreliable
- requires lifestyle changes - some unwilling
name pollutants released by burning fuels and how they are formed (4)
- carbon monoxide: incomplete combustion
- particulates (soot - unburned hydrocarbons): incomplete combustion
- sulphur dioxide: sulphur impurities in fuel reacting with oxygen
- nitrogen oxides: nitrogen+oxygen in air is heated
effects of the 4 pollutants
- carbon monoxide: toxic gas, colourless/odourless so not easily detected
- particulates: global dimming (block sunlight), respiratory problems (particles inhaled), cancer
- sulphur dioxide: acid rain, respiratory problems
- nitrogen oxides: acid rain, respiratory problems
equation for complete combustion of hydrocarbon fuels
hydrocarbon + oxygen -> carbon dioxide + water
equation for incomplete combustion of hydrocarbon fuels
hydrocarbon + oxygen -> carbon dioxide + carbon monoxide + carbon (soot) + water
