Earth’s AtmosphereEarth’s Atmosphere

I Earth’s AtmosphereI Earth’s Atmosphere A. What is the atmosphere?

1. A ________ blanket of air2. A ________________ layer3. Weather is a result of _____________ between the

atmosphere and Earth’s surface and between Earth’s surface and the atmosphere

thinprotective

interaction

B. Composition of the Atmosphere

1. Air is a _________ of gases.

2. Varying amounts of tiny _______ and ________ particles are suspended in the atmosphere.

3. The composition is ____ constant.

mixture

solidliquid

not

4. Major Componentsa. __________ (N2): ≈78

b. _________ (O2): ≈ 21%

c. _______________ (CO2): ≈ 0.04%

78%

21%

0.04%

0.934%

NitrogenOxygenCarbon Dioxide

≈ 1.0%

Carbon Dioxide

• Meteorologically important despite its presence in minute amounts.

• Proportion is relatively uniform, but the percentage has been steadily rising for more than a century.

CO2 measurements at Hawaii’s Mauna Loa Observatory(Oscillations are caused by season variations in plant growth and decay.)

5. Variable Components

a. _________________ (1) Varies from almost zero to about four

percent by volume.

(2) Significance: (a) It’s a good heat ____________.

(b) It’s a source of ____________ for

many storms.

Water Vapor

absorber

heat energy

Latent Heat

i) When water changes from one phase to another, it ________ or ________heat.

ii) This “hidden” heat is termed _________heat.

gains loseslatent

b. __________(1) Suspended ________ and ________ particles

(a) Most are microscopic(b) Visible dust can be suspended for short periods of

time.

Aerosolsliquid solid

AerosolsAerosols

(2) Important in cloud formation as the surfaces on which water vapor may condense.

(3) Can be a type of pollutant and can reduce the amount of sunlight reaching Earth’s surface.

(4) Contribute to varied hues of red and orange sunrise and sunset.

Sunset Affected by Volcanic Ash

Sidney, Australia after the eruption of Mt. Pinatubo

5. Originate from________ and_____________ sources

(a) Sulfur dioxide and dust from volcanic eruptions

natural human-made

(b) Smoke and soot from fires

Industrial SourcesIndustrial Sources

(c) Fine soil particles

(d) Sea Salts from breaking waves

(e) Pollen and other microorganisms

c. ________

(1) Triatomic form of Oxygen (______)

(2) Forms as a result of the collision of an atom of oxygen (O), a molecule of oxygen (O2). Reaction is a result of ___________________ solar radiation splitting molecules of oxygen.

(3) Concentrated in the upper ______________.

(4) Also a photochemical pollutant at Earth’s surface.

Ozone

O3

short-wave ultraviolet

stratosphere

Formation of Ozone in the Stratosphere Formation of Ozone in the Stratosphere

( ( ( ( ≈ 10 to 50 km altitude) 10 to 50 km altitude)

The The Ozone-Oxygen CycleOzone-Oxygen Cycle

Destruction of Ozone by Free Destruction of Ozone by Free Chlorine AtomsChlorine Atoms

Source of Chlorine –Source of Chlorine –Chlorofluorocarbons (CFC’s)Chlorofluorocarbons (CFC’s)

Source of Chlorine –Source of Chlorine –Chlorofluorocarbons (CFC’s)Chlorofluorocarbons (CFC’s)

Source of Chlorine –Source of Chlorine –Chlorofluorocarbons (CFC’s)Chlorofluorocarbons (CFC’s)

Source of Chlorine –Source of Chlorine –Chlorofluorocarbons (CFC’s)Chlorofluorocarbons (CFC’s)

The Montreal Protocol - 1987The Montreal Protocol - 1987

• Signed in 1987, more than 40 countries agreed to phase out ozone depleting compounds by 2000.

The Antarctic Ozone HoleThe Antarctic Ozone Hole• Caused in part by

abundant ice particles in the Antarctic stratosphere.

• Ice increases ability of CFCs to destroy ozone.

• Maximum depletion is confined to the Antarctic by a swirling in upper-level wind pattern in the southern hemisphere spring.

Sept. 17, 2001- The ozone hole covers anarea about the size of North America.

Blue colors = sparsest ozoneLight blue, green, and yellow indicate progressively more ozone

Effects of Increased UV Radiation Concentrations – Skin Cancer

Additional cases of skin cancer, especially among fair-skinned peopleand those who spend considerable time in the Sun

Cataracts – A Clouding of the EyeCataracts – A Clouding of the Eye

Reduction in Crop Yields and QualityReduction in Crop Yields and Quality

Antarctic Phytoplankton Could Be Impaired or Destroyed

•These microscopic plants are the base of the food chain.

• Could reduce the krill and copepods that sustain fish, whales, and other marine life in higher latitudes of the Southern Hemisphere

Marine Food Chain InteruptedMarine Food Chain InteruptedCopepod

Krill

C. C. Height and Structure of the Height and Structure of the AtmosphereAtmosphere

1. Data Collection

Balloons and RadiosondesBalloons and Radiosondes

Radiosondes are lightweight instrument packages thattransmit data. They are released twice daily.

Lower Altitudes High Altitudes

AirplanesAirplanes

Dropwindsonde (Dropsonde)Dropwindsonde (Dropsonde)

RocketsRockets

SatellitesSatellites

2. The Vertical Extent of the Atmosphere

a. There is ______________________defining the end of the atmosphere and the beginning of space.

b. A majority of the atmosphere is ___________Earth’s surface and the gases gradually merge with the void of space.

c. _____________of the atmosphere is below an altitude of 5.6 km (3.5 mi)d. _____percent lies below 16 km (10 mi.)e. Above 100 km (62 mi.): 3.0 x 10 -5 of gases remain. This is the official

altitude of ___________.

no sharp boundary

very near

One-half90

space

The X-15 Flew to the Edge of SpaceThe X-15 Flew to the Edge of Space

• The X-15 was released at high altitudes from a B-52• It made 199 flights between 1959 and 1968.• Maximum altitudes of flights ranged from 81.5 km to 107.0 km

Even at High Altitudes There’s AirEven at High Altitudes There’s Air

Apollo 15 re-entry

Space Shuttle Columbia

• As Columbia descended from space into the atmosphere at 120 km, the heat produced by air molecules colliding with the Orbiter typically caused wing leading-edge temperatures to rise steadily, reaching an estimated 2,500 degrees Fahrenheit (1400° C).

3.3. Classification of the AtmosphereClassification of the Atmospherea. By Composition

(1) ________________: Up to an altitude of about 80 km (50 mi) makeup of the air is uniform in terms of the proportions of its component gases.

(1) ___________________(a) Above 80 km

composition is not uniform

(b) Four roughly spherical shells (lowest is nitrogen, then atomic oxygen, followed by a layers of helium, and hydrogen).

Heterosphere

Homosphere

Homosphere

Heterosphere

b. By Temperatureb. By Temperature

(1) ___________________:(a) The bottom layer in which we

live.(b) Temperatures _________with

altitude (“environmental lapse rate”)on the average of 6.5o C per kilometer (3.5o F per mile).

(c) Temperature decrease continues to about 12 km but is thickest at the equator (16 km or about 10 miles) and thinnest at the poles (9 km or about 5.5 miles)

(d) This is the chief focus of meteorologists because it is in this layer that all important weather phenomenon occur.

Troposphere

decrease

b. By Temperatureb. By Temperature

(2)______________:

(a) Above the troposphere(b) The ______________ is the boundary between the troposphere and

stratosphere.(c) Temperature remains

constant to about 20 km (12 mi) and then sharply increases.

Stratosphere

Tropopause

d. The cause of temperature increase in upper stratosphere is the concentration of atmospheric ________.ozone

b. By Temperatureb. By Temperature

(3) ________________

(a)Temperatures_________`

with height. (b) The coldest temperatures anywhere in the atmosphere are at the

_____________.(c) One of the least explored regions of the

atmosphere.(i) Balloons can’t go

that high.(ii) Not accessible to

lowest orbiting satellites.

Mesosphere

decrease

Mesopause

b. By Temperatureb. By Temperature

(4)______________________(a)No well-defined upper limit.(b)Contains only a minute

fraction of the atmosphere’s total mass (rarefied and considered a vacuum.

(c) Temperatures increase due to absorption of very shortwave, high-energy solar radiation by atomic oxygen and nitrogen.

(d)While temperatures may be extremely high, the total amount of heat is very low because the gases are so sparse. As a result, an object (such as a satellite) exposed to the air in this layer would not feel hot.

Thermosphere

(c) ______________

(1) Electrically Charged layer (2) Shortwave solar radiation ionizes molecules of nitrogen and oxygen(3) Between 80 to 400 km altitude (50 to 250 mi) is zone of the greatest density(4) Shortwave solar radiation ionizes molecules of nitrogen and oxygen.(5) Actually three layers (D, E, and F which is the highest). D and E layers weaken at night.(6) Little impact on daily weather. (7) Used for short-wave radio communications.

The Ionosphere

Aurora Borealis, the northern lights and Aurora Australis, southern lights

• Correlated with solar-flare activity and in geographic location with Earth’s magnetic poles.

• Clouds of protons and electrons streaming from the Sun are guided by the magnetic field towards the poles.

• The ions energize atoms of oxygen and nitrogen causing them to emit light – the glow of the auroras which is often multicolored streamers.

Evolution of Earth’s Evolution of Earth’s AtmosphereAtmosphere

Origin of the Solar System (Solar Nebula Theory)Origin of the Solar System (Solar Nebula Theory)

1. Planets formed at the same time as the Sun and from the same nebular material.

2. The Solar System is believed to be 4.6 billion years old.

The Solar NebulaThe Solar Nebula• Solar system born 4.6 billion

years ago• A few light-years in diameter• Composed mostly of gaseous

– Hydrogen (71%)– Helium (27%)– Traces of other gases

• Microscopic dust– Mixture of silicates, iron compounds, carbon compounds and water ice

• Collapse may have been triggered by a nearby exploding star or a collision with another cloud

(A) Collapse of an interstellar cloud(B) The cloud flattens into a disk(C) Condensation of dust grains in the solar nebula and

formation of planetesimals

Earth’s Accretion from Planetesimals

SummarySummary1. Huge gas and dust cloud became

unstable.a. Due to gravitational attraction a condensation

formed at one point becoming the Sunb. The cloud rotated faster as it contracted.c. Some gas and dust was left in a flattened disk

surrounding the protosun.d. Condensation occurred within the disk forming

protoplanets which continued to move in the same direction as the disk.

2. As material in the disk became more concentrated in the protoplanets:a. Space between the new Sun and the protoplanets

cleared;b. Light and heat was able to reach them driving off

lighter elements and even most of its atmosphere leaving a more dense core of heavier elements.

Terrestrial Planets

• Closer to the Sun and most lighter elements driven off.

• Small, rocky, and dense

• Mercury, Venus, Earth, Mars

• No atmosphere. (Originally)

• Shortly after accretion, Earth was – a rapidly rotating, hot, barren, waterless planet– bombarded by comets and meteorites– with no continents, intense cosmic radiation – and widespread volcanism

Hot, Barren, Waterless Early EarthHot, Barren, Waterless Early Earth

• about 4.6 billion years ago

                • Numerous impacts from objects from space

(meteors, comets)• Volcanic Outgassing: Atmosphere evolved from the

release of water from volcanoes.

 

Origin of the Atmosphere & OceansOrigin of the Atmosphere & Oceans

CometsComets

• A new class of comets, “main belt comets” may have formed within the orbit of Jupiter– Contain “Heavy” water (HDO) which has equal parts Hydrogen,

Oxygen, and Deuterium (an isotope of H with extra neutron)

• Earth’s oceans contain HDO• Comet impacts might have contributed significant water

to the formation of Earth’s atmosphere and the oceans.

Hydrogen Deuterium

  Origin of Earth’s OceansOrigin of Earth’s OceansRelease of water from precipitation over millions

of years early in Earth history.

Earth’s Early AtmosphereEarth’s Early Atmosphere

Was Devoid of Free Oxygen

Earliest OrganismsEarliest Organisms

• Primitive Prokaryotic Cells• Anaerobic

• Heterotrophic

• Photomicrographs from western Australia’s– 3.3- to 3.5-billion-year-old Warrawoona Group, – with schematic restoration shown at the right of each

Fossil ProkaryotesFossil Prokaryotes

• Adenosine Triphosphate ATP– Most likely nutrient source from their environment– Was used to drive the energy - requiring reactions in cells

• ATP can easily be synthesized– from simple gases and phosphate– so it was doubtless available – in the early Earth environment

• Obtaining ATP from the surroundings could not have persisted for long because more and more cells competed for the same resources

Source of Energy for Earliest Source of Energy for Earliest OrganismsOrganisms

• Most likely used by the first organisms to develop a more sophisticated metabolism

• Used by most living prokaryotic cells to meet their energy needs

• Fermentation is an anaerobic process – Molecules such as sugars are split– Carbon dioxide, alcohol, and energy are released

• C6H12O6 2CO2 + C2H5OH + Energy

• Organisms evolved the ability to synthesize their needs from simple inorganic substances

Fermentation

Origin of Free OxygenOrigin of Free Oxygen

• A very important biological event – The development of the autotrophic process of

photosynthesis– Occurred in the Archean– May have occurred as far back as 3.5 billion

years ago

• 6H2O + 6 CO2 + Sunlight C6H12O6 + O2

• These anaerobic, autotrophic prokaryotes – belong to the Kingdom Monera, – represented today by bacteria and

cyanobacteria

Photosynthesis

– From the Early Proterozoic Gunflint Iron Formation of Ontario, Canada – that he proposed represented reefs constructed by

algae

Oldest Known OrganismsOldest Known Organisms

• Now called stromatolites, – not until 1954

were they shown

– to be products of organic activity Present-day stromatolites Shark Bay, Australia

Stromatolites:Stromatolites:Builders of Limestone and Producers of OBuilders of Limestone and Producers of O22

• Cyanobacteria – older incorrect term is

blue-green algae

– Photosynthetic bacteria

• Secret CaCO3 in daily cycles

• Traps sand and forms layers in various mound-like formations

Stromatolite Fossils in NY State

Sea Gardens State Park, Saratoga