The Atmosphere

Question 1

how do scientists believe the gases in the atmosphere came to be? (2)

Answer 1

• they think that during the first billion years, there was intense volcanic activity
• these volcanoes released the gases that formed the atmosphere

Question 2

what happened to water vapour as the earth cooled?

Answer 2

it condensed to form oceans

Question 3

what did the earth’s atmosphere consist of in the early stages?

Answer 3

mainly carbon dioxide with little or no oxygen

Question 4

what exactly did the volcanoes release in the first billion years? (3)

Answer 4

• water
• carbon dioxide
• small amounts of nitrogen

Question 5

what are the differences between the early atmosphere and the atmosphere today? (3)

Answer 5

EARLY ATMOSPHERE
- contained large amounts of carbon dioxide
- contained very little oxygen
- contained very small amounts of nitrogen

ATMOSPHERE TODAY
- contains small amounts of carbon dioxide
- 21% of the atmosphere is oxygen
- 78% of the atmosphere is nitrogen

Question 6

how did the changes in the levels of carbon dioxide in the atmosphere happen? (6)

Answer 6

• water vapour condensed to form oceans
• at this stage, some carbon dioxide dissolved in the oceans to form a weak acid
• this reacted with minerals in the sea to form precipitates
• over time, this formed sediments of carbonate rock on the sea bed

2.

• some of the carbon dioxide in the sea was used to make corals and shells of organisms, such as mussels
• when these died, they formed the sedimentary rock limestone and this also removed carbon dioxide from the atmosphere

Question 7

where did the oxygen in today’s atmosphere come from? (3)

Answer 7

• around 2.7 billion years ago, photosynthetic algae first evolved in the oceans
• photosynthesis produced oxygen, which then entered the atmosphere
• over the following billion years, plants evolved and this increased the amount of oxygen in the atmosphere

Question 8

what is coal formed from?

Answer 8

the remains of ferns or trees

Question 9

how is coal formed? (3)

Answer 9

• if these ferns and trees die in marshy wetlands, they do not decompose due to either lack of oxygen or acidic conditions
• over time, the plant remains are covered with sediment and compressed
• high temperature and pressure creates coal

Question 10

what is crude oil formed from?

Answer 10

• plankton, which are tiny plants and animals found in the sea

Question 11

how is crude oil formed? (3)

Answer 11

• when the plankton die, they settle in the mud on the sea bed and if oxygen isn’t present then they do not decompose
• over time, they are compressed by sediment
• heat and pressure convert them into crude oil

Question 12

what is natural gas formed from?

Answer 12

plankton, formed in a similar way to oil

Question 13

what do all fossil fuels contain?

Answer 13

trapped carbon

Question 14

three greenhouse gases

Answer 14

• water vapour
• carbon dioxide
• methane

Question 15

how does energy from the sun travel to the earth?

Answer 15

as short wavelength radiation
e.g. ultraviolet and visible light

Question 16

what happens to the short wavelength radiation from the sun?

Answer 16

some of it reflects back into space but most of it passes easily through the atmosphere

Question 17

what happens when the energy of short wavelength radiation reaches the surface of the earth?

Answer 17

it’s absorbed

Question 18

how does the earth radiate the energy from the sun back out?

Answer 18

as long wavelength radiation
e.g infra-red

Question 19

what happens to the long wavelength radiation?

Answer 19

it interacts with the greenhouse gas molecules in the atmosphere

or

the energy within it is absorbed

Question 20

what are the two ways in which humans are increasing the amount of carbon dioxide in the atmosphere?

Answer 20

1.burning fossil fuels
- we burn coal for electricity
- burn petrol and diesel to power cars
- burn gas to heat our homes

2. deforestation
   - carbon dioxide is normally absorbed by growing trees but by cutting those trees down, the carbon dioxide has no where to go and the carbon dioxide already taken in is just released

• in many cases, forests are burned to provide land for grazing cattle
• burning forests releases large amounts of carbon dioxide

Question 21

how are methane levels increasing within the atmosphere?

Answer 21

• released in agriculture (flooded paddy fields)
• released when cows pass wind

Question 22

what are the detrimental effects of climate change? (3)

Answer 22

• rising temperatures will increase the melting of the polar ice sheets and glaciers, which will lead to increased sea levels
• increased sea levels could lead to more flooding of low-lying areas
• climate change could lead to more severe weather
  e.g more storms in the uk

Question 23

define carbon footprint

Answer 23

the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event

Question 24

how can we reduce carbon dioxide emissions? (5)

Answer 24

• insulating our homes or turning down the heating
• using public transport to reduce the amount of carbon dioxide released by driving
• switching to renewable sources of electricity
• switch to energy-saving lightbulbs
• turn appliances off by the plug rather than leaving them on standby

Question 25

how can we reduce methane emissions? (2)

Answer 25

• by eating less beef and dairy products
• trapping the methane from landfills and burning it to produce electricity