The atmosphere is a blanket of gases that
extends from the surface of the Earth and
reaches over 560 kilometers (348 miles)
The troposphere is the
lowest region of the
Earth's atmosphere, where
masses of air are very well
mixed together and the
temperature generally
decreases with altitude.
Occasionally, a temperature inversion occurs, and the temperatures
actually increase with altitude within this zone.
Most weather on Earth occurs within the troposphere,
because this is where the water vapor is.
General Altitude of the troposphere is from 14-18 km.
The environmental lapse rate is the actual
decrease in temperature with an increase in
altitude through the troposphere. Sometimes, ELR
is also known as “normal lapse rate.
While many things influence the “normal lapse rate
of temperature, in general, the temperature
decreases with altitude at an average rate of .65oC
/100 meters.
Take a moment to discuss with your partner what types of
factors may impact the normal lapse rate within the
troposphere.
In the stratosphere, the air
is stable and less turbulent.
• The temperature of the air
within the stratosphere
increases with altitude.
This increase in temperature with altitude is
due to the presence of stratospheric
OZONE near an altitude of 25 km.
Ozone molecules absorb high-energy ultraviolet rays from
the sun, which warm the atmosphere at that level.
The stratosphere extends to 50 km.
In the Earth's mesosphere,
the air masses are relatively
mixed together and the
temperature decreases with
altitude. This is also the layer
in which a lot of meteors burn
up while entering the Earth's
atmosphere.
Limb
The mesosphere extends from the top of the
stratosphere (50 km) to an altitude of about
90 kilometers, and can be detected by
looking at the limb.
When the Sun is active, temperatures within this zone can reach up to
1,500°C, or higher! The thermosphere can extend above the Earth’s
surface as far as 480 km.
The thermosphere also includes
the region of the Earth's
atmosphere called the ionosphere.
When a rapidly moving particle,
such as an electron, collides with
a gas atom, an electron is ejected
from the atom, leaving a positively
charged ion.
Ionization processes release energy, which heats up the
upper atmosphere. Temperature, therefore, increases with
altitude in the ionosphere and it is extremely hot compared
to surface temperatures.
Even thought the ionosphere represents less than
0.1% of the total mass of the Earth's atmosphere,
it is extremely important.
Different regions of the ionosphere make
long distance radio communication
possible by reflecting the radio waves back
to Earth.
The space shuttle flies in this
area of the atmosphere, and
this is also where the aurora
borealis, and aurora australis
are found.
Auroras are wispy curtains of light
caused when the sun strikes gases in
the atmosphere above the Polar
regions.
The region of our atmosphere where atoms and
molecules escape Earth’s gravitation and move into
space is referred to as the exosphere.
This is truly the upper limits
of Earth’s atmosphere, and
some of our satellites are
stationed in this area.
• It is 500 to 1000 km
above the Earth’s surface
A region within and beyond the exosphere is known as the
magnetosphere. It is not truly a layer of Earth’s atmosphere
so it is not bound by gravitation, but by magnetism.
When learning about the Greenhouse Effect, it is important
to understand the electromagnetic spectrum, and the
lengths of waves within it.
• Radio waves
• Microwaves
• Infrared waves (IR)
• Visible light (ROYGBIV)
• Ultra Violet (UV)
• X-Rays
• Gamma Rays
In order, from
longest to
shortest
wavelengths, the
spectrum is as
follows:
• Sunlight travels through space in a very short and
powerful wavelength, known as Ultra violet (UV).
• Some UV radiation is reflected or absorbed by
the ozone (O3) molecules located in our
This UV light is not
stratosphere
seen by our eyes (as
only visible light is
within the
spectrum our eyes
can detect).
However, it can
be detected by
our skin when
we get a
sunburn, or feel
warmed by the
sun.
• Some UV radiation as well as visible light is able to
penetrate the atmosphere and hit the Earth’s surface.
• Some of that UV radiation and visible light which
reaches the surface is absorbed by vegetation, soil,
water, and rock.
Which Earth surfaces do you think are
responsible for the greatest absorption?
As you may
remember, it is
this heating of
the water over
our tropical
oceans that
drives much of
the climate on
our planet.
Albedo is the reflection
coefficient, or the reflecting
power of a surface.
It is defined as the ratio of
reflected radiation from the
surface to incident radiation
upon it.
Albedo is measured on a scale
from zero for no reflecting
power of a perfectly black
surface, to 1 for perfect
reflection of a white surface.
Typical albedo ranges from 0.9 for
fresh snow, to about 0.04 for
charcoal, black asphalt, and lava
rock
• Some of that radiation (which is absorbed) is converted,
and re-radiated back into Earth’s troposphere as long wave,
less powerful radiation known as Infra-red
• This long wave Infrared radiation (IR) is unable to
penetrate the Earth’s greenhouse gas layer, and
becomes trapped, as heat energy near the surface
The IR radiation (just
in our atmosphere
like the UV) is not
seen by our eyes, but
it can be felt as
warmth on our skin.
Many scientists
believe it is this effect
that is causing the
global rise in
temperatures known
as Global Warming.
Global Warming was first recognized by
Svante August Arrhenius in 1896. His
meteorological studies made him conclude
that the weather patterns had changed in
Sweden since the beginning of the industrial
revolution (1800). He proposed that burning
of fuels was causing these changes.
He was correct of course in that burning fossil fuels indeed
had contributed to global warming.
 80% of the Earth's increase in temperature is
due to the burning of fossil fuels like coal and oil
and the resulting CO2 emissions. The industrial
revolution has been fueled by coal and oil.
 The other 20% occurs naturally and comes from
decomposing vegetation.
CO2 (carbon dioxide): 25% increase in last 200 years.
CFCs (chlorofluorocarbons): used as solvents to clean
computer chips and keep the cool (a.k.a. Freon) in air
conditioners. One CFC molecule can absorb 20,000
times more infrared energy than CO2 molecules.
CH4 (methane): increasing 11% per year. One CH4
molecule can absorb 25x the IR as CO2 molecules
(caused by burning of biomass, and livestock emissions)
NOx (nitrous oxides): accelerated by the use of
nitrogen-based fertilizers. Absorbs 250x more IR than
CO2
O3 (ozone): very minor influence
H2O (water vapor): not caused by humans
Current estimates indicate that CO2 is responsible for about one half
the problem. CH4 and NOx each contribute one fourth.
As ominous as this all sounds, this
greenhouse effect is vital to life on Earth.
With no atmosphere on the moon: (no
atmosphere means no greenhouse effect)
• In the illuminated half, the temperatures
often reach 216° F
• In the dark half, the temperatures often
plummet to -243° F
Without greenhouse effect on Earth, the
average temperature would be -27° F
The one greenhouse gas that has truly been increasing in
the past 50 years is carbon dioxide.
Loss of rainforests that take in carbon dioxide, and the
burning of fossil fuels by cars, factories and plants which
release carbon dioxide are part of the causes.
In the Troposphere:
• low concentrations
In the stratosphere, (6 to 30
miles above the surface) the
chemical compound ozone
plays a vital role in absorbing
harmful ultraviolet radiation
from the sun.
 sources:
 hydrocarbons
 small amounts
of stratospheric
ozone
O3
Natural Tropospheric
Ozone:
• Lightning and
• static discharges
Ozone gives off the acrid
smell after a lightning
discharge. Some ozone is also
produced when natural
hydrocarbons, such as the
terpenes in coniferous trees
react with nitrogen oxides in
the atmosphere and sunlight.
The ozone that is a byproduct of certain human activities
does become a problem in the troposphere, and this is what
we think of as 'bad' ozone. With increasing populations,
more automobiles, and more industry, there's more ozone in
the lower atmosphere.
• Since 1900 the amount of ozone near the Earth's
surface has more than doubled.
• Unlike most other air pollutants, ozone is not directly
emitted from any one source.
•Anthropogenic tropospheric
ozone is formed by the
interaction of sunlight,
(particularly ultraviolet light)
with hydrocarbons and
nitrogen oxides (NOx), which
are emitted by automobiles,
gasoline vapors, fossil fuel
power plants, refineries, and
certain other industries.
• In urban areas in the Northern Hemisphere, high
ozone levels usually occur during the warm, sunny
summer months (from May through September).
• Typically, ozone levels reach their peak in mid to
late afternoon, after the sun has had time to
react fully with the exhaust fumes from the
morning rush hours.
• In early evening, the
sunlight's intensity
decreases and the
photochemical
production process
that forms ground level
ozone begins to subside.
While stratospheric ozone protects us from ultraviolet
radiation, in the troposphere this irritating molecule
damages forests and crops; destroys nylon, rubber, and
other materials; and injures or destroys living tissue. It is a
particular threat to people who exercise outdoors or who
already have respiratory problems.
Ozone affects plants in several
ways. High concentrations of ozone
cause plants to close their stomata.
Closed Stomata means:
• Slowed photosynthesis
• Little or no food produced
• Eventually starving plant
Sometimes ozone may enter
open stomata, and directly do
damage to internal cells
When ozone pollution
reaches high levels, pollution
alerts are issued urging
people with respiratory
problems to take extra
precautions or to remain
indoors.
Ozone has been linked to tissue
decay, and the promotion of scar
tissue formation. It can impair an
athlete's performance, create
more frequent attacks for
individuals with asthma, cause eye
irritation, chest pain, coughing,
nausea, headaches and chest
congestion and discomfort.
It can worsen heart disease,
bronchitis, and emphysema.
The most dramatic
phenomenon
associated with
the stratospheric
ozone layer over
recent decades has
been the rapid
growth in the
region of an ozone
“hole” in the
Antarctic during
the spring
Oct 1-15 2009
The depletion of
ozone can
greatly be seen
over Antarctica
in the Southern
Hemisphere
where the region
has total ozone
levels at less
than 220 Dobson
Units (DU)
The ozone hole has gotten smaller each consecutive year,
since 2006.
While the use of ozone depleting chemicals, such as CFCs,
was phased out in 1987 under the Montreal Protocol, they
are still present in the atmosphere, and only decreasing at a
rate of 1% per year.
Ozone molecules don't last very long, with or without
human intervention. The vehicle necessary to transport
such enormous amounts of ozone into the stratosphere
does not exist now, and, if it did, it would require so much
fuel that the resulting pollution might undo any positive
effect.
• Decrease production
of chemicals that
break-down ozone
• Find alternatives to
those chemicals
Christian Friedrich Schoenbein discovered ozone in 1839.
He used the reactivity of ozone to measure its presence and
demonstrate that it is a naturally occurring component of
the atmosphere. He developed a way to measure ozone in
the troposphere using a mixture of starch, potassium
iodide, and water spread on filter paper. The paper, called
Schoenbein paper, changes color when ozone is present.
Ozone causes iodide to oxidize into iodine.
2 KI +
O3 + H2O--> 2 KOH + O2 + I2
I2 + starch --> blue color
This test is based on the oxidation of ozone. Ozone in the air will
oxidize the potassium iodide on the test paper to produce iodine.
The iodine reacts with starch, staining the paper a shade of purple. The
intensity of the purple color depends on the amount of ozone present
in the air. The darker the color, the more ozone is present.
Will the results be Qualitative or
Quantitative ? Tomorrow, we’ll make some Schoenbein Paper!