11 The Earth's atmosphere

Question 1

What is the atmosphere?

Answer 1

a layer of gas surrounding the Earth

Question 2

What was the early atmosphere composed of?

Answer 2

mostly carbon dioxide

Question 3

How did the oceans form?

Answer 3

water vapour condensing as the Earth cooled

Question 4

How did the amount of carbon dioxide in the atmosphere decrease to today’s levels?

Answer 4

dissolved in the oceans, photosynthesis, converted to fossil fuels, precipitated as insoluble metal carbonates

Question 5

When did life start to appear, and what was the impact of this on oxygen in the atmosphere?

Answer 5

about 2.7 billion years ago; amount of atmospheric oxygen increased as it was released in photosynthesis

Question 6

How has the amount of nitrogen in the atmosphere changed over time?

Answer 6

increased slowly as it is a very stable molecule

Question 7

Why can scientists not be sure about the composition of the Earth’s early atmosphere?

Answer 7

it was billions of years ago and evidence is limited

Question 8

What is the current composition of the atmosphere?

Answer 8

approximately 80% nitrogen, 20% oxygen, and trace amounts of other gases such as carbon dioxide, water vapour, and noble gases

Question 9

What is a greenhouse gas?

Answer 9

a gas that traps radiation from the Sun

Question 10

What type of radiation do greenhouse gases absorb?

Answer 10

longer wavelength infrared radiation

Question 11

Name three greenhouse gases.

Answer 11

methane, carbon dioxide, water vapour

Question 12

Give two ways recent human activities have increased the amount of atmospheric carbon dioxide.

Answer 12

burning fossil fuels, deforestation

Question 13

Give two ways recent human activities have increased the amount of atmospheric methane.

Answer 13

rice farming, cattle farming

Question 14

What is global warming?

Answer 14

an increase in the overall global average temperature

Question 15

What is global climate change?

Answer 15

the change in long-term weather patterns across the planet

Question 16

What are some possible effects of climate change?

Answer 16

sea levels rising, extreme weather events, changes in the amount and time of rainfall, changes to ecosystems and habitats, polar ice caps melting

Question 17

What is a carbon footprint?

Answer 17

the amount of carbon a product, process, or person releases into the atmosphere over its lifetime

Question 18

How is carbon monoxide formed, and what is the danger associated with it?

Answer 18

incomplete combustion; colourless and odourless toxic gas

Question 19

How are particulates formed, and what are the dangers associated with them?

Answer 19

incomplete combustion; global dimming, respiratory problems, potential to cause cancer

Question 20

How is sulfur dioxide formed, and what are the dangers associated with it?

Answer 20

sulfur impurities in fossil fuels react with oxygen during combustion; acid rain, respiratory problems

Question 21

How are oxides of nitrogen formed, and what are the dangers associated with them?

Answer 21

atmospheric oxygen and nitrogen react in the heat of a combustion engine; acid rain, respiratory problems