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Atmosphere and Climate
Julieanne Quigley 2.2017
The Atmosphere
• The nearby planets of
Mars and Venus are
barren and lifeless. Why
does our planet have
life?
• One thing that makes
life possible on earth is
its atmosphere
• The atmosphere is a
thin layer of gases that
surround the earth
The Atmosphere
• The atmosphere is 78%
nitrogen and 21 %
oxygen. The remaining 1%
is: water vapor, argon,
carbon dioxide, neon,
helium and other gases.
• We call this entire
mixture air.
• The most important of
the air’s gases for
organisms are oxygen and
carbon dioxide
The Atmosphere
• Oxygen is necessary for
cellular respiration and
carbon dioxide is necessary
for photosynthesis
• The earth’s atmosphere
protects living things from
most of the sun’s harmful
UV radiation at the same
time it allows visible light to
reach the earth’s surface
supplying earth with energy
and making photosynthesis
possible
Photosynthesis and the Atmosphere
• Living things played a very important role in forming the
atmosphere we know today.
• Early earth’s atmosphere contained very little oxygen and a lot
of CO2
• Early organisms evolved the ability to do photosynthesis and
slowly changed the atmosphere from high levels of CO2 to
high levels of oxygen
Layers of the Atmosphere
• Scientists have found it
useful to think of the
atmosphere as five
individual layers.
–
–
–
–
–
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
Layers of the Atmosphere
• The troposphere
extends from the
earth’s surface to about
10km above the surface
• It contains about 90% of
the atmosphere’s gases
• The air we breathe is a
part of the troposphere
• It is where weather
occurs
Layers of the Atmosphere
• The Stratosphere extends
from 10kn -50km above
the earth.
• The air in the
stratosphere is less dense
• Commercial airliners
often travel in the lower
part of the stratosphere
• Stratosphere contains the
ozone layer
Layers of the Atmosphere
• Beyond the
stratosphere is the
mesosphere,
thermosphere and the
exosphere
• The gases in the
exosphere become
thinner and thinner
until the exosphere
merges with outer
space
Climate
• Weather occurs mostly
in the troposphere, the
atmospheric layer that
touches the earth’s
surface, but…
• WHAT IS WEATHER??
Climate
• Weather is simply what
is happening in the
atmosphere at a
particular place at a
particular moment
• Climate on the hand, is
the average weather in
an area over a long
period of time
• Temperature, humidity,
wind and precipitation
are important factors in
determining climate
Climate
• Climate is determined
by a variety of factors:
latitude, air circulation,
ocean currents and
local geography of the
area.
• The most important of
these factors is latitude
Latitude
• Latitude is the distance
from the equator,
measured in degrees
north or south of the
equator
• The equator is defined as
0⁰.
• The most northerly
latitude is the North Pole,
at 90⁰ North
• The most southerly
latitude is the South Pole,
at 90⁰ South
Latitude
• Latitude strongly influences climate because the amount of
solar energy an area receives depends on latitude
• More solar energy falls on areas near the equator that areas
closer to the poles
Atmospheric Circulation Patterns
• Three important
properties of air explain
how air circulation affects
climate:
– Cold air sinks and warms as
it sinks
– Warm air rises and cools as
it rises
– Warm air can hold more
water vapor than cold air
can therefore, if warm air
is cooled, the water vapor
it contains condenses into
a liquid forming rain or
snow
Atmospheric Circulation Patterns
• Solar energy heats the ground, which warms the air above it. This
warm air rises, and cooler air moves in to replace it. Heating of
the atmosphere therefore causes wind, or the movement of air
within the atmosphere
• Because different latitudes receive different amount of solar
energy, the patterns of global circulation result
Atmospheric Circulation Patterns
• The circulation pattern
determines global patterns
of precipitation
• Rainforest example: Intense
solar energy strikes the earth’s
surface at the equator causing
the air above it to become
warm, this warm air can hold
large amounts of water that
evaporates from the ocean
and land. As the air rises,
however, it cools and loses
some of its ability to hold
water, thus, it rains heavily at
the equator!
Atmospheric Circulation Patterns
• Desert example: cool air normally sinks, but the cool air
over the equator cannot descend because hot air is
moving up below it. So this cool air is forced away from
the equator, toward the poles. It sinks back to earth at
a latitude of about 30⁰, warming as it falls. This warm,
dry air moves across the surface causing water to
evaporate from the land below causing extremely dry
conditions!
Ocean Circulation Patterns
• Ocean currents have a great effect on climate because water
hold large amounts of heat.
• The movement of surface ocean currents is caused largely by
winds and the rotation of the earth.
• These currents redistribute warm and cool masses of water
Seasons
• Temperature and precipitation
change with the seasons.
• Seasons are the result of the
earth’s orbit around the sun,
earth has a 23⁰ tilt which
means the angle at which the
sun’s rays strike the earth
changes as the earth moves
around the sun.
• During spring and summer the
northern hemisphere tilt
toward the sun and the
southern hemisphere tilts
away. It is the opposite in the
fall and winter
Seasons
• Four seasons do not occur in the tropics, which are
the so close to the equator, they receive direct
sunlight year round.
• In the far north and far south there are months of
complete darkness and complete light
Greenhouse Earth
• Have you ever gotten in your car that has been sitting the sun
for a while with all the windows closed. Even if the day is cool,
the air inside the car is much warmer than the air outside.
• Heat builds up inside the car because the sun’s energy streams
into the car through the glass, carpets and upholstery absorb
the heat and the heat energy doesn’t pass back out though
the glass
The Greenhouse Effect
• The earth is similar to a
green house. We live
inside “greenhouse earth”
like delicate plants,
surrounded by the icy
coldness of outer space.
• The earth’s atmosphere
acts like the glass in a
green house, sunlight
streams through the
atmosphere and heats
the earth.
The Greenhouse Effect
• As heat radiates up from the earth, some of it escapes into space.
• The rest of the heat is trapped by gases in the troposphere and
warms the air
• This process is called the greenhouse effect
The Greenhouse Effect
• Not every gas in our
atmosphere traps
heat. The gases that
DO trap and radiate
heat are called
greenhouse gases
• The major
greenhouse gases are
water vapor, carbon
dioxide,
chlorofluorocarbons
(CFCs), methane, and
nitrous oxide.
• After water vapor,
carbon dioxide is the
most important of the
greenhouse gases.
Carbon Dioxide
• Carbon dioxide levels are
rising globally.
• Carbon dioxide levels rise
and fall with the daily
rhythms of
photosynthesis, but due
to fossil fuel burning and
industrial pollution the
carbon dioxide levels
have been increasing over
the past 50 years at an
alarming rate.
Carbon Dioxide
• During photosynthesis, a plant
takes in carbon dioxide from
the air, some of the carbon in
the carbon dioxide becomes
part of the plant’s body, this
carbon is not returned o the
air
• When fossil fuels are burned,
carbon is released into the air.
• If the amount of carbon
dioxide is low, plants are able
to recycle it… but, there is too
much carbon for plants to
recycle all of it
Carbon Dioxide and Greenhouse Gases
• Since greenhouses gases trap
heat hear the earth’s surface,
many scientists think that
more greenhouse gases in the
atmosphere will result in a
warmer earth
• Today we are releasing more
carbon dioxide into the
atmosphere than any other
green house gas along with
many others
• Global warming is a predicted
increase in temperature due to
too many greenhouse gases
Warmer Earth…
• The earth’s climate has changed dramatically in the
past as over hundreds and thousands of years
• Currently scientists believe the earth’s climate is
changing very rapidly due to increases in carbon
Warmer Earth
• Weather patters- change as
climate changes. Hurricanes and
typhoons are more common,
severe flooding and devastating
droughts
• Agriculture- disruptions in earth
patterns hit farmers very hard.
As temperatures change,
farming becomes more and
more difficult
• Sea levels- as polar regions
warm, icebergs break loose from
glaciers and let in the sea
causing sea levels to rise and
coastal cities to be in danger of
flooding
Slowing the temperature change
• Reduce fossil fuel use
• Reduce carbon footprint
• Forests should be
preserved
• More trees should be
planted
• Monitor greenhouse gas
emissions
• Create laws banning
greenhouse gases
The Ozone Shield
• The stratosphere contains the earth’s ozone shield
• Ozone is a form of oxygen with molecules made of three oxygen
atoms
• Ozone in the stratosphere absorbs most of the UV light from the
sun
• UV light is very harmful to organisms because it can damaged DNA
in living cells
• Shielding the earth’s surface from most of the sun’s UV radiation,
the ozone in the stratosphere acts like sunscreen for the earth
Ozone Eaters
• During the 1970’s scientists discovered
chlorofluorocarbons were damaging the ozone. CFC’s
were used in coolants and spray bottles
• CFC’s are stable at the earth’s surface, but as they move
up in the atmosphere, they break the bonds of the ozone.
It is thought that a single CFC can break apart as many as
10,000 ozone molecules
The Ozone Holes
• NASA stated: Ozone
layers near the south
pole had thinned by up
to 90% in the early
1990’s.
• After this was
discovered, laws were
put into place to limit
greenhouse gases and
to try to protect the
ozone
Thinning Effects
• As the ozone decreased,
more UV light was able to
enter the earth. UV light is
dangerous because it can
alter DNA in organisms.
• High levels of UV light can
destroy single celled
organisms and cause
mutations in larger
organisms.
• Skin cancer has increased
dramatically in humans over
the last 20 years.
Ozone Healing…
• Since the 1990’s
– Industrialized countries agreed to eliminate more CFC’s by 1995
– The US banned all substances that pose a danger to the ozone by 2000
– Industrialized countries agreed to set up a fund to help developing countries switch to
substitutes for CFC’s
• More recently- A huge “Green” movement is sweeping the world and most
people are working hard to recycle, reduce carbon foot print, reduce fossil
fuels and do as much as they can to protect the ozone and the entire planet