1 Atmosphere

Question 1

weather vs climate

Answer 1

short term fluctuations in the atmosphere that produce
precipitation, winds, and variable temperatures

long term fluctuations in the atmosphere that produce
patterns of precipitation, winds and temperatures

Question 2

• about __% of the atmosphere lies within the

troposphere, 16 km above the surface

Answer 2

90

Question 3

Atmospheric layers from surface up(9)

Answer 3

1. Troposphere (0-18km)
2. Tropopause
3. Stratosphere(18-50)
4. Ozone
5. Stratopause
6. Mesosphere(50-80)
7. Mesopause
8. Thermosphere(80-120)
9. Exosphere

Question 4

the ________ is where the weather we

experience occurs

Answer 4

troposhere

Question 5

exosphere

Answer 5

• the exosphere extends to ~190,000 km
above Earth’s surface, about 1/2 the way to
the moon
• ISS orbits at 330-435 km

Question 6

Atmospheric Composition: 2 groups, describe each

Answer 6

• we can divide the composition of the atmosphere into 2 groups:
• gases: most of the atmosphere is made of gas, and these can be
further divided into permanent and variables gases
• solids and liquids: these are collectively known as aerosols, and are
vital components of weather and climate

Question 7

aerosols are…

Answer 7

• solids and liquids: these are collectively known as aerosols, and are
vital components of weather and climate

Aerosols play a much different role then gases:
.are affected by gravity and will not remain in the atmosphere once placed there,short term before falling back to earth
-reflect radiation and cool off VS. GHG absorb and heat up
-affect visibility and are mostly sources from cars

Question 8

permanent gases

vs

variable gases

Answer 8

• permanent gases(found in homosphere) are considered to be constant in the atmosphere
(< 80 km above Earth’s surface)
-well mixed in turbulent air flow

variable gases(found in heterosphere) are minor components in the atmosphere, but vary
greatly in both space and time
• these gases are naturally occurring, but can be strongly influenced by
human activities
• despite their minor amounts in the atmosphere, they have important
effects on local and global scales
-gas stratification in laminar(calm) air flow

Question 9

% in atmosphere

Argon

Niitrogen

Oxygen

Answer 9

1

21

78

Question 10

Nitrogen

Answer 10

-must be converted to nitrate for life use
• N2
is an inert gas that is unavailable to most organisms, but N is a critical
nutrient for most life
• to make N bioavailable, the N2 must be converted to more useful forms,
typically as nitrate – through lightning or bacteria via nitrogen fixation
• denitrifying bacteria convert
nitrate back into N2O, a natural
and powerful greenhouse gas
• N2O is destroyed in the
stratosphere through
photodissociation, breaking
down into N2 or NO, thus
maintaining a steady state
atmospheric nitrogen system

Question 11

Oxygen

Answer 11

• O2
is highly reactive, and originates from photosynthesis, the process by
which inorganic carbon is converted into organic carbon
• O2
is removed from the atmosphere
through respiration, decomposition,
and combustion
• these processes typically result in the
emission of CO2
• oxidation also removes O2
from the
atmosphere, but is slower than above
 iron bearing minerals in rock are
converted into ferric (aka rust) or
ferrous iron

Question 12

water vapour

Answer 12

• originates from evaporation at Earth’s surface (ie, the oceans)
• the movement of water between Earth’s surface and the atmosphere is
the core of the hydrologic cycle
• water moves to the atmosphere by evaporation, and back to the
surface by precipitation
• spatially, the amount of water vapour in the air varies
• over deserts and ice caps, the % volume is < 0.5%
• over the tropical oceans and forests, 4%
• water vapour contributes directly to cloud and precipitation formation
• also, it is an effective absorber of energy, and is the most important of
the greenhouse gases
• satellites use this ability to map spatial changes in atmospheric
water vapour

• water vapour in the atmos is greatest at the equators and becomes less and less as you head to the poles
• south pole is the least

Question 13

carbon dioxide

Answer 13

• while we can sense changes in atmospheric water vapour, we cannot
sense changes in atmospheric carbon dioxide
• CO2
is known as a trace gas, because it’s overall contribution to the
atmospheric composition is so low – 0.0395%
• normally, we call this 395 parts per million (ppm)
CO2 + H2O + sunlight  CH2O + O2
• CO2 comes from plant and animal
respiration, decaying organic material,
volcanic eruptions, and natural and
human combustion
• CO2
is removed from the atmosphere
through photosynthesis

• under normal conditions, the release of CO2
into the atmosphere
equals the removal from the atmosphere
• again, stability does not imply constancy
• however, over the past few centuries, CO2 concentration in the
atmosphere has been rising beyond natural ranges
• since the 1950s, the rate of increase is 2.15 ppm per year
• this has been attributed to human effects, primarily fossil fuel
combustion and deforestation
• like water vapour, CO2
is a very effective greenhouse gas, and the rise
in atmospheric CO2
is believed to contribute to “global warming”

Question 14

Ozone

Answer 14

• although considered a trace gas (0.01% of atmosphere), it is essential to
the existence of life on Earth
• ozone occurs primarily in 2 places
• near the surface
• in the lower troposphere, ozone is a major pollutant, causing
eye, lung, and vegetation damage
• in the stratosphere
• creates the ozone layer which blocks incoming ultraviolet
radiation

Ozone:few km thick at the top of the stratosphere

• concentrate at poles because of severe seasons
• ozone distruction can only happen in the prescense of light
• worse in south pole because it is MUCHMUCH colder

Question 15

since the 1950s, the rate of increase of carbon dioxide is ____ ppm per year

Answer 15

2.15

Question 16

T OR F

Earths’ surface is the largest source of heat for the atmosphere

Answer 16

T

Question 17

• atmospheric CO2 has
been measured in
_____ since 1958

Answer 17

Hawaii

Question 18

• as of 25 August 2018,
CO2 concentration was
at _____ ppm

Answer 18

406.63

Question 19

______ causes oxygen molecules to split and become free oxygen atoms that eventually collide with molecules of oxygen creating ozone molecules

Answer 19

high energy ultra violet radation

Question 20

Ozone destruction

Answer 20

• the ozone molecule is destroyed by chlorine-bearing molecules, such as
chlorofluorocarbons (CFCs), which have no known natural sources
• CFCs are used in coolant products for air conditioners and
refrigerators, and survive in the atmosphere for 100s of years
• the chlorine (Cl) in the CFCs reacts with the ozone (O3
) to convert it to O2
Cl + O3  ClO + O2
ClO + O  Cl + O2
• the reactions are driven by sunlight, so in subpolar to tropical regions, the
destruction occurs year round at a constant rate
• but at the poles, CFCs accumulate in the stratosphere during the dark
winter, and when the Sun rises in spring, a massive ozone depletion event
occurs, leaving a residual “ozone hole

Question 21

Ozone as a greenhouse gas

Answer 21

• ozone is also a powerful greenhouse gas
• in the lower troposphere
• ozone absorbs solar radiation, warming the surrounding air and
leading to surface warming
• in the upper stratosphere
• ozone absorbs solar radiation, warming the surrounding air and
leading to stratospheric warming
• this is why the top of the stratosphere is warmer than the bottom
• however, ozone depletion reduces this warming, leading to
stratospheric cooling

Question 22

Methane

Answer 22

• methane gas is a minor component of the atmosphere (< 0.0002%), but is
a powerful greenhouse gas
• methane concentration in the atmosphere has always varied in a
cyclical pattern, but this pattern stopped 5000 years ago and methane
concentration began to steadily rise
• this is the same time that rice agriculture began to flourish
• methane will play a major role in future climate change

Question 23

Aerosols

Answer 23

• aerosols are the non-gaseous components of the atmosphere, mainly in
the form of small solid particles and liquid droplets
• aerosols are produced by both natural and human processes
• aerosols are strongly affected by gravity, so the largest particles are
quickly brought to the surface – smaller aerosols may last longer in the air
• aerosols often work against greenhouse gases – instead of absorbing
energy, they reflect it, leading to a cooling of the air

Question 24

Examples of Natural aersols(4) vs anthropogenic aersols(3)

Answer 24

wind-generated dust
erupted volcanic material
salts from sea-spray
forest fire combustion

fossil fuel combustion
material cement manufacturing
agriculture

Question 25

____ often work against greenhouse gases – instead of absorbing
energy, they reflect it, leading to a cooling of the air

Answer 25

aerosols

Question 26

critically, aerosols have 2 major effects of the atmosphere

Answer 26

1. they affect visibility (eg, smog, dust storms)
2. they act as condensation nuclei
   • when raindrops form, the water vapour in the atmosphere needs
   a solid object to condense onto (turn from gas to liquid)

Question 27

Describe temperature as it moves through 4 parts of atmosphere

Answer 27

.Decreasing from surface through troposphere to tropopause

.at tropopause temperature begins to increase until stratopause

.at stratopause temperature decreases to the atmospheres minimum temperature until mesopause

.at mesopause temperature begins to increase exponentially through thermosphere until end of atmoosphere

Question 28

Turbopause

Answer 28

seperates the homosphere from the heterosphere at approximately 80 km above the surface

Question 29

Describe density of atmpsphere

Answer 29

• density (of any substance) is the mass of a substance contained in a
given volume
• for solids and liquids, this is easy to measure
• however, gases are compressible, and therefore the same amount
of gas can be contained in both a large or small container
• since the atmosphere is primarily a gas, it is compressible
• the air in the atmosphere is being compressed by the air above it, so
the air near Earth’s surface is being compressed by all the air that lies
above it
• this means that air near Earth’s surface is the most dense, and
density decreases as you move upward

-• we can think of density as the concentration of air molecules in a given
space
• near the surface where compression (and density) is greatest, there
are lots of molecules packed tightly together
• in fact, at Earth’s surface an air molecule can only travel
0.0001mm before it collides with another air molecule
• higher up, at 150km above Earth’s surface, an air molecule must
travel 10m before it collides with another air molecules
• those air molecules produce resistance – a lot of molecules pushed
together resist motion more than loosely packed molecules
• this is why airplanes travel quickly at high altitudes
• or, why footballs and baseballs travel further in Denver

Question 30

define density

Answer 30

• we can think of density as the concentration of air molecules in a given
space

Question 31

Boyle’s Law

Answer 31

the relationship between the pressure and volume of a
gas is constant

pv=k

• where p is the pressure, V is the volume, and K is a constant
• this law shows that as the pressure increases, the volume must
decrease, and vice versa
• at the bottom of the atmosphere, where pressure is the greatest, the air
molecules are compressed into a smaller volume, increasing the density

Question 32

Troposphere

Answer 32

• major features:
• nearly all weather occurs in the troposphere
• the thinnest layer, but contains 80% of the atmospheric mass
• in general, temperature decreases with height (-6.5 °C per km)
• the thickness of the troposphere ranges from 8 to 16 km, and averages
11 km
• this thickness is controlled by temperature - it is thickest over warm
areas (tropics) and thinnest over cold areas (poles)
• the temperature at the bottom of the troposphere is Earth’s surface
temperature – what we experience
• at the top of the troposphere, the temperature decrease stops, and
temperature becomes constant – this is known as the tropopause

Question 33

• why doesn’t temperature increase as you move upwards towards the
Sun?

Answer 33

• the atmosphere isn’t actually warmed by the Sun directly
• instead, the Sun’s radiation passes through the atmosphere to Earth’s
surface, where it is absorbed
• the warm surface then warms the air above it, and vertical
movement of air through the atmosphere transmits this warmth
• this is why the bottom of the troposphere is the warmest
• sometimes though, temperature increases with height
• this is known as an inversion, and is an important factor in
atmospheric motion and pollution

Question 34

Temperature Inversion

Answer 34

• inversions act as physical boundaries in the atmosphere, which restrict
motion across them
• air will move from places of high density and/or temperature to low
density and/or temperature
the dominant motion is away from
the inversion peak, and air will not
easily cross the inversion

similarly, shockwaves from ground
explosions can be completely
reflected by an inversion, sending
the energy back to the surface
the tropopause shares these
characteristics, restricting air
exchange between the troposphere
and stratosphere

• inversions occur very frequently in Arctic environments, because the
ground (sea ice, permafrost, glacial ice) keeps the lower air cool while
upper air is warmer
• in winter, up to 80% of days experience inversions
• in summer, 20 – 60% of days experience inversions

summer inversions appear to have
a strong influence on glacial melt
in the Canadian Arctic
an increase in inversion frequency
in 1987 coincides with increased
rates of ice melt

Question 35

Stratopshere

Answer 35

from the Greek “stratos”, meaning layer – this is because the stratosphere
is relatively stable compared to the troposphere (air doesn’t easily move
vertically)
• other than very tall thunderstorms that penetrate the tropopause,
weather does not occur in the stratosphere
• the bottom of the stratosphere is cold, being about the same as the top
of the troposphere
• but the stratosphere warms with height, and the top of the stratosphere –
the stratopause at about 50 km above Earth’s surface – is about 0 °C
• as we noted earlier, this is due to the ozone layer in the stratosphere
• about 19.9% of the atmospheric mass is in the stratosphere
• recall that 80% was in the troposphere

Question 36

Stratosphere and Ozone

Answer 36

• the heating of the stratosphere is dominated by the effects of ozone
• this produces a very stable situation, where vertical winds are not
produced
• also, being far away from the oceans, the supply of water vapour is
minimal, so the air in the stratosphere is very dry
• precipitation does not occur in the stratosphere
• occasionally, powerful volcanic eruptions spew aerosols into the
stratosphere
• since there is no water vapour, these aerosols are not used as
condensation nuclei, but instead create a thin reflective shield around
the planet
• after major volcanic eruptions, Earth’s temperature cools because of
this effect

Question 37

Mt Pinatubo in 1991

effect on stratosphere

Answer 37

Global temperature decreased tremendously after eruption of Mt Pinatubo in 1991

Question 38

__% of the atmosphere exists above the stratopause

of that __%, __% is found in the mesopshere

Answer 38

0. 1

99. 9

Question 39

Mesopshere and Thermosphere

Answer 39

• of the 0.1% of atmospheric mass above the stratopause, 99.9% exists in
the mesosphere, which extends to a height of 80 km above Earth’s surface
• the top of the mesosphere marks the top of the homosphere, where
the permanent gases are most consistent
• the mesosphere is warmed by the stratosphere below, and vertical winds
transmit the heat upwards
• the thermosphere extends to a height of 120 km, and temperature
increases rapidly up to a maximum of 1500 °C
• however, the air is so thin at this height that you would never feel this
heat, because it is the air molecules that carry that energy
• our concept of heat does not work at these altitudes

Question 40

.Thunderstorms have flat tops because that when they meet the _____

Answer 40

stratosphere

Question 41

Temperature

Answer 41

• the temperature of air is related to its kinetic energy, which is in turn
related to the speed at which the molecules are moving
• the amount of heat contained within the air is dependent on this
temperature, and also on the mass of the air
• since the thermosphere contains so few air molecules, the heat
content is very low despite the individual molecules having high kinetic
energy (a high temperature)
• in fact, an air molecule at the top of the thermosphere may have to
move several kilometres before meeting another molecule

Question 42

3 temperature scales

Answer 42

• Fahrenheit scale: the first
temperature scale, but currently only
used by the US
-based of human body temp(100 degrees is human)
• Celsius scale: more conventional
than Fahrenheit, and is the
internationally recognized scale
-based on water
• Kelvin scale: a modified form of
Celsius, but does not include negative
values
-at 0 kelvin, molecules are not moving whatsoever

Question 43

0 degree celcius is ___ on the kelvin scale

Answer 43

273

kelvin scale has no negatives

Question 44

Ionosphere

Answer 44

• while we distinguish the mesosphere and thermosphere by their thermal
properties, they also contain strong changes in electrical properties
• from the upper part of the mesosphere through the thermosphere,
electrically charged particles known as ions are found
• an ion is produced when an air molecule is bombarded by solar
radiation, which strips off an electron, resulting in a positively charged
ion and a free electron

• we interact indirectly with
the ionosphere everyday
• the ionosphere reflects
radio waves, allowing us
to listen to radio without
have a clear few of the
transmission tower

Question 45

• an ___ is produced when an air molecule is bombarded by solar
radiation, which strips off an electron, resulting in a positively charged
ion and a free electron

Answer 45

ion

ions produce northern lights

Question 46

_________ makes radio posible

Answer 46

ionosphere

Question 47

Evolution of atmosphere

Answer 47

• the solar system originated as
a nebula, created by a nearby
supernova
• the rotating nebula began to
separate, with the Sun forming
first at the centre and small
rocky bodies forming in circular
orbits
• through the heavy
bombardment period, the large
rocky masses collided with
each other, forming larger and
larger planets

• if the atmosphere formed at the same time that Earth formed, it is about
4.6 billion years old
• if so, it must have contained mainly hydrogen and helium, the 2
most abundant, and lightest, elements in the early solar system
• but these gases are too light to be held by Earth’s gravity, and they
slowly escaped into space during the first ½ billion years of Earth’s
existence
• this primordial atmosphere would have been replaced by gases
released by outgassing, volcanic eruptions and comet inputs
• these gases were mainly water vapour, carbon dioxide, nitrogen,
and sulphur dioxide – the same stuff that volcanoes emit today
• also, small comets may have brought water vapour to Earth
• this atmosphere lasted another ½ billion years
• this H2O, CO2
, N, and SO2 atmosphere has obviously changed, but
where did it go?
• as Earth cooled, the water
vapour condensed, fell to Earth
and created the oceans
• at the same time, the carbon
dioxide dissolved into the rain
drops and produced
carbonate rocks
• the sulphur was incorporated
into the sulphur cycle, a key
biogeochemical cycle involved
in life
• the nitrogen remained
about 3.5 billion years ago, bacteria began to flourish
• the photosynthetic bacteria breathe in CO2 and expel O2
, thus
helping to reduce the CO2 content and also producing an oxygenrich
atmosphere
• at the same time, this newly produced oxygen gas was being
bombarded by ultraviolet radiation, producing the ozone layer
• by 1.7 billion years ago, an oxygen-rich atmosphere with a protective
ozone layer opened the door for more complex lifeforms

Question 48

Why earth is Earth and Mars and Venus are not as friendly to life?

Answer 48

• Earth, Mars, and Venus share a similar origin, but their atmospheres have
evolved differently
• Venus has a very dense atmosphere composed mainly of CO2
• since Venus is closer to the Sun, it would not have cooled as much as
Earth, any H2O would have stayed in the atmosphere and
photodissociated into H and O – no atmospheric H2O means no removal
of CO2
through rain
• Venus experiences a very large greenhouse effect

• Mars has a very sparse atmosphere composed mainly of CO2
• since Mars is further from the Sun it is colder and H2O and CO2 can be
found in solid form at the Martian poles
• Mars is also less massive than Earth and Venus, so it has less gravity and
cannot hold onto light atmospheric molecules easily, so they escape into
space

Question 49

Gaia Hypothesis

Answer 49

• Earth is the Goldilocks planet, not too close to the Sun, but also not too
far – just the right distance for liquid water to occur
• liquid water promotes life which generates O2 and rain washes CO2 out
of the air
• the Gaia Hypothesis