Earth's atmosphere

Question 1

define atmosphere

Answer 1

a layer of gases surrounding Earth or another planet held in place by the planet’s gravity

Question 2

air is …

Answer 2

compressible and one can determine its density

Question 3

where is the atmosphere at its densest and lowest?

Answer 3

densest - sea level

higher altitudes- lower

Question 4

why is it important for life on earth ?

Answer 4

1) it absorbs the sun’s energy
2) recycles water and other chemicals
3) moderates climate
4) protects life from high energy radiation

Question 5

properties change with height

Answer 5

thinner with height with no definite boundary between atmosphere and outerspace
oxygen decreases with height

Question 6

Name the 5 atmospheric layers

Answer 6

1) the troposphere
2) stratosphere
3) mesosphere
4) thermosphere
5) exosphere

Question 7

the troposhpere

Answer 7

1) the air we breathe
2) extends to 15 km high
3) temperature falls with altitude of -50 degrees Celsius
4) all weather is in this region
5) tropopause - separates the troposphere from stratosphere

Question 8

the stratosphere

Answer 8

1) starts above the troposphere and extends 50km above Earth’s surface
2) less water vapour and less dense
3) temperature increases with height -3 degrees Celsius =absorption or radiation
4) ozone layer - absorbs and scatters uv rays
5) the stratopause separates from the mesosphere

Question 9

The mesosphere

Answer 9

1) Just above the stratosphere -extents to 85km
2) temperature falls with increases altitude to about -90 degrees celsius
3) mesospause separates the mesosphere from the thermosphere

Question 10

the thermosphere

Answer 10

1) extends to an altitude of 600 km
2) highly ionized with gases
3) temperatures increasing with altitude up to 1700 degrees celsius

Question 11

the exosphere

Answer 11

1) outermost layer
2) extremely dilute gases ; hydrogen and helium with atoms escaping
3) sometimes considered as the interface between atmosphere and space as it gradually merges into space with no clear boundary

Question 12

composition of the atmosphere

Answer 12

nitrogen 
oxygen 
carbon dioxide 
other gases 
water vapour is also present but varies because warmer air holds more

Question 13

solar budget

Answer 13

The total solar energy received by Earth and the total energy radiated back to space must be equal because Earth’s overall temperature changes

Question 14

solar constant

Answer 14

the amount of solar energy received at the top of Earth’s atmosphere (varies due to slight changes in distance between earth and sun

Question 15

where does the sun’s energy go ?

Answer 15

Half of it is absorbed by the atmospheric gases(ozone and water vapour ) or reflected and scattered by clouds and dust - the rest is absorbed by Earth’s surface

Question 16

Global circulation

Answer 16

Energy transfer with the earth’s atmosphere system - not all parts of earth received the same amount of solar energy ex the poles receive far less than the equator

Question 17

how is heat transferred?

Answer 17

heat transfers form warmer to colder areas - the uneven distribution of heat produces convention currents which redistribute heat energy - these convention currents are experienced as winds and ocean currents (otherwise the tropics would get warmer and the poles would get colder )

Question 18

how does it happen exactly ( heat transfer )

Answer 18

intense heating at the equatorial region initiates convention currents - this warm air rises at troposphere - flows horizontally towards poles and eventually returning to earth’s surface (30 north and 30 south )
this massive convention current is called the Hadley Cell

Question 19

the 2 other cells

Answer 19

the polar cell and the Ferrel cell

Question 20

The albedo

Answer 20

the proportion of incident light that is reflected by a surface - depends on the albedo of the surface receiving sunlight

Question 21

what affects the albedo ?

Answer 21

1) different colour and texture - clean snow ( high reflectivity ) - forest ( low reflectivity )
clouds - high reflectivity

Question 22

what happens if the planet’s albedo changes

Answer 22

increases- cooling of global temperature

decreases - warmer planet

Question 23

The greenhouse effect

Answer 23

incoming and outgoing radiation balance out however they have different properties

1) the incoming radiation is a mixture of ultraviolet , visible and infra-red radiation- these radiation are of a short wavelength
2) Earth radiates back heat with a longer wavelength of infra-red radiation
3) Earth’s atmosphere contain gases that absorb some of this thermal radiation emitted - re-radiate energy in all direction - warming effect - greenhouse effect

Question 24

Greenhouse gas

Answer 24

a gas that absorbs thermal infrared radiation and therefore contributes to the greenhouse effect

Question 25

Greenhouse effect definition -

Answer 25

the warming effect of the atmosphere that occurs when infrared energy is emitted by earth’s surface is absorbed by gases in atmosphere - a fundamental natural phenomenon to life on earth - temperature which sustains life

Question 26

name the greenhouse gases

Answer 26

1) water vapour
2) carbon dioxide
3) methane
4) ozone
5) nitrous oxide
6) chlorofluorocarbons

Question 27

sources of greenhouse gases

Answer 27

landfills- methane emissions
deforestation - a large amount of carbon dioxide
combustion of fossil fuels - carbon dioxide

Question 28

The ozone layer

Answer 28

• the stratosphere zone -
  protects life from the damaging uv rays
• the ozone is constantly created and destroyed but because of human activity the increasing rate of destruction is resulting in the disruption of balance - will lead to ozone depletion