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Exam 1 for Earth and Science


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Earth Science
All the sciences that collectively seek to understand Earth and its neighbors in space
Physical Geology
examines the materials of the earth and seeks to understnad the processes and forces acting beneath and on the earth's surface
Historical Geology
studies the origin of the earth and its development through time- sequence of fissils in rock beds
the study of the atmosphere and the processes that produce weather and climate
the study of the universe; it includes the observation and interpretation of celestial bodies and phenomena
it is a dynamic place with many interacting parts that form a complex and continuously interacting whole- "earth system". A change in one part of the earth system can produce changes in one or any of all of the other parts
a thin layer of gases (below 480 km) surrounding the Earth, and held to the Earth by gravity; it forms a protective boundary between outer space and the biosphere
an abiotic open system that includes all the Earth's waters (surface, atmosphere, and crustal; and gaseous, solid, and liquid)
the earh's crust and that portion of the upper mantle directly below the crust that extends downward to 70 kilometers (km) (45 miles)
biosphere (ecosphere)
that area where the atmosphere, hydrosphere, and lithosphere function togeather to form the context within which life exists
was valid only insofar as it predicted and explained the observations on which it was based
scientific method
to the pricnciples and processes that guide scientific investigation. it provides the framework within which scientists try to discover the laws governing the natural (observable) world
The goal of science
the job of the scientist is to learn about the natural world that surrounds them; to attempt to discover how and why it works and the way it does. this taks is made easier because the universe is a regualr and predictable place. It is the job of the scientist to discern the predictable pattersn, and discover the "simple laws" that are responsible for them. Science thus operates under the following assumption: natural laws that control our universe exist, and can be understood by the human mind.
How our present way of conducting science came to be
the first science was astronomy. It came out of a practical need for a reliable calender that could be used to assist farmers. In the earth 17th century, men like Galileo first began to make careful and systematic observations of natural phenomenon and to try explaining them. Galileo made many careful measurements. He and some of his contemporaries introduced the concept that a theory was valid only insofar as it predicted and explained the observations on which it was based. The thus established a close connection between observations and theory, which is the essence of the scientific method (scientific inquiry)
steps involved in the scientific method
observation, hypothesis/theory, the scientific law
a scientist begins by making an observation about some system. It can involve the making of measurements of the properties of the system that is being observed. These measurements can range, for example, from finding the size of some object, to finding the length of time it takes for some process to occur. An importatnt characteristic of measurement is that its accuracy is always limited: in part from inaccuracies inherent in any measuring device.
the hypothesis/theory
the scientist then comes up with a hypothesis to answer his/her question and explain his/her obsrevations. After a hypothesis has been formulated, it must be tested. It must predict the observations; if it doesn't, it must be discarded and another found. In order for a hypothesis to be considered valid, it must be (experimentally) veridied. (One way of testing a hypothesis is to conduct a controlled experiment). If a hypothesis has survived extensive scrutiny, and competing hypotheses have been eliminated, a hypothesis is elevated to the status of a scientif theory
The scientific law
after a theory has survived many years of experimental investigation, it is frequently accourded the status of a scientific law.
Our galaxy (the "milky way") and solar system
our sun and solar system is within the MILKY WAY GALAXY- just one of millions within the universe. our sun is just one of billions within the universe. The milky way galaxy is a "spiral galaxy", and we are located far out from the center of the galaxy on one of the spiral arms- the "orion Arm"
Galactic Dimensions
speed of light: 299,792 km/sec at this speed, the distance that light can travel in one year is more than 9 trillion km. This distance is called a "light year" we use the "light year" as a distance unit. 1 light year=9,454,000,000,000 km our moon=1.28 seconds away in light speed
Formation of our solar system: "nebula hypothesis"
our solar system formed from a rotating, cloud of gas, dust, and ice- a "nebula" (4.6 billion years ago). A proto-sun at the center of the nebula wehre the most mass existed. The rotating cloud of gas and dust flattened out an assumed a disk shape. Mass accumulated by "accretion" away from the center of the nebula- protoplanets. the protoplanets grew in size- "planetsimals". as the proto-sun grew in size it became hotter due to intense pressures; and eventually thermonuclear reactions within the sun occurred- fusion- the conversion of hydrogen to helium- which releases tremendous amounts of energy
our solar system
in comprised of nine planets: Mercury, Venus, Earth, Mars (which are all terrestial planets), Jupiter, Saturn, Uranus, Neptune (which are all Jovian planets), and Pluto. The terrestrial, or inner planets, are small, dense, and rocky, and metalic, with minor amounts of gases. the Jovian, or outer planets, are large, not very dense, and contain a large % of gases.
the state of the atmosphere at any given time; a short period of time
a description of longer time scale of weather conditions; the sum of all statistical weather information that helps describe a place or region; it also includes the estremes
weather/climate elements
air temperature, humidity, cloud cover (type and amount), precipitation (type and amount), atmospheric pressure, wind (speed and direction)
weight of the overlying atmosphere pressure (force per unit area) of the atmosphere decrease with height above the ground
Pressure is often used as vertical coordinate in meterological applications
a measurement of the average speed of the atoms and molecules that comprise air. Higher temperatures correspond to faster average speeds
3 temperature scales
fahrenheit, celsius, and kelvin scales
evolution of the earth's atmosphere
earth's atmosphere has changed significantly since the earth was first formed!
Primordial Atmosphere
derived from the solar nebula (existed short time frame)
Evolutionary Atmosphere
gases derrived from the earth's interior- outgassing; "purple sulfur bacteria" produced organic materials from inorganic elements (3.6 billion years ago)
Living atmosphere
first photosynthesis by "blue- green algae" (3.3 billion years ago)
Modern Atmosphere
abundance of life as a consequence of high levels of oxygen
Earth's present day atmosphere
total mass of the atmosphere (5.1 EE 21 grams), total mass of the earth (6.0 EE 27 grams), mass of the atmosphere (one millionth mass of the earth)
Composition of the Atmosphere
Natural Air (clean air + pollutants), clean air (dry air + water vapor), and Dry air
Dry air (in % by volume)
Nitrogen (N2) 78.98%
Oxygen (O2) 20.95%
Argon (Ar) 0.93%
Trace Gases: He, Ne, Kr, Xe, Rn, and H2
Water vapor
a variable constituent of clean air
4% in warm, moist tropical air
0% in cold, dry, polar air
Variable constituents of dry air (trace amounts):
Ozone (O3), carbon monoxide (CO), sulfur oxides (SOx), nitrogen oxides (NOx), carbon dioxide (CO2)
Vertical structure of the atmosphere
pressure, temperature, and density
mass per unit volume (m/v) of the atmosphere also decreases with height above the ground
the layer of the atmosphere nearest the earth to 10km where temperature generally decreases with height, the location of most of the atmosphere's moisture and consequently weather, upper boundary is the tropopause
the layer above the tropopause (10-50km) where temperature generally increases with height, very stable (warmer air over cooler air) > thus vertical motions are weak, has a low moisture content > few clouds, upper boundar is the stratopause, most of the atmosphere's ozone (O3) is found here at 25km, ozone in the stratosphere is destroyed when it absorbs ultraviolet radiation from the sun (O3 molecule becomes atomic (O) and molecular (O2) oxygen). Some of the absorbed energy warms the stratosphere the ozone layer protects biological life below from dangerous UV radiation. Top of the stratosphere is the stratopause
the layer above the stratosphere (50-80 km) where temperature increase with height again, O2 (molecular oxygen) is photodissociated here, O2 absorbs UV radiation from the sun, and in the process, heating of the atmosphere occurs. Because of the low density of molecules and atoms, a small amount of UV energy absorption produces a large temperature increase
Vertical structure by composition
homosphere and heterosphere
(0-80 km) a well mixed region where the composition is uniform due to turbulent mixing.
(80 km gaes are layered by atomic weight-less mixing here)
Vertical Structure by Function
(mainly in the thermosphere)- an electrified reigon within the upper atmosphere where large concentrations of ions and free electrons exist- it filters harmful wavelengths of solar radiation
Air pollution
The Problem of air pollution is as old as civilization itself!!
Genesis (19:28): "Abraham beheld the smoke of the country go up as the smoke of a furnace"
Hippocrates (~400 B.C.): Noted the filth of the cities
An English Diarist (~1684): "the air in London was so filled with smoke that one could hardly see across the street"
Air pollution is most problematic in urban areas..... has increased markedly since the industrial revolution... and is closely associated with cars, buses, and trucks
Natural Sources of Air Pollution
produce a greater quantity of pollutants than human-made sources
Volcanoes: SOx, particulates
Forest Fires: CO, CO2, NO2, particulates
Plants: HCs, pollens
Decaying Plants: CH4, hydrogen sulfide
Soil: dust and viruses
Ocean: salt spray and particulates
Anthropogenic (Human-Caused) Air Pollution
*carbon monoxide (CO) incomplete combustion of fuels
*nitrogen oxides(NOx) high temperature combustion
*hydrocarbons HC incomplete combustion of fuels
*ozone (O3) photochemical reactions
*PAN photochemical reactions
*sulfur oxides (SOx) combustion of sulfur-containing fuels
particulates dust, dirt, soot, salt, metals, organics
carbon dioxide (CO2) complete combustion
water vapor combustion processes, steam
methane (CH4) organic processes
"Primary Pollutants"
are emitted directly from identifiable sources . They pollute the air imediately after being emitted.
"Secondary Pollutants"
are not emitted directly into the air, but form in the atmosphere when reactions take place among the primary pollutants
Industrial Smog
"smog" = smoke + fog
industrial smog - contains: SOX, particulates, CO2 ....
sulfur dioxide:
results from combustion of fossil fuels, colorless, but pungent
impairs breathing - esp. breathing impaired individuals
can be transformed to sulfuric acid and sulfate aerosols
can be transported downwind to Canada
70% of Canada’s SO2 originates in U.S
Photochemical Smog
Results from the interaction of sunlight and combustion products of automobile exhaust
NOx and Hydrocarbons (HC)
assoc. with hazy sky and reduced sunlight in urban areas
Nitrogen dioxide (NO2 )
reddish brown gas, damages and inflames respiratory systems
an ozone precursor
Hydrocarbons (HC)
assoc. with the combustion of fossil fuels - automobiles and power plants/factories
an ozone precursor
Ozone (O3)
affects the human respiratory system - (12 million children are at risk of developing health problems from ozone pollution)
damages plants (loblolly pine), reduces crop yields, weakens rubber and fabrics
forms as a secondary pollutant
NOx and HCs chemically react in the presence of sunlight to form ozone
Consequences of a Decrease in Stratospheric Ozone
an increase in the number of cases of skin cancer
an adverse impact on crops and animals due to an increase in energetic ultraviolet radiation
a cooling of the stratosphere that could affect stratospheric wind patterns, possibly inducing some form of climate change
for every 1% decrease in ozone, skin cancers increase by 5-10%
Ozone forms naturally in the stratosphere: molecular oxygen combines with atomic oxygen in the presence of another molecule
Ozone is destroyed naturally by absorbing UV radiation
Ozone is also destroyed by colliding with other gases, e.g., nitric oxide and nitrogen dioxide
Human activities are altering the amount of stratospheric ozone
Used as propellants in spray cans, refrigeration units, plastic foams for insulation, packing, furniture, solvents, and styrofoam containers
CFCs in aerosol cans have been banned in the US, Canada, Scandinavia since 1978, however, aerosol CFC production has increased overall in W. Europe as have worldwide nonaerosol CFCs
Once CFC molecules enter the middle stratosphere, ultraviolet radiation breaks them up, releasing chlorine in the process -- the chlorine then rapidly destroys ozone (one chlorine atom removes ~ 100,000 ozone molecules
The average lifetime of a CFC molecule is about 100 years
Acid Deposition
Air pollution emitted from industrial areas, especially products of combustion, such as oxides of nitrogen (NOx), and oxides of sulfur (SOx) can be transported considerable distances downwind
These materials (gases and aerosols) either settle to the ground in dry form (dry deposition) or are removed from the air during the formation of cloud particles and are then carried to the ground in rain, snow, or fog (wet deposition)
Formation of Acids
Emissions of sulfur dioxide and oxides of nitrogen may settle on the local landscape, where they transform to acids as they interact with water, especially during the formation of dew or frost
Airborne particles may transform into tiny dilute drops of sulfuric acid (H2SO4) and nitric acid (HNO3) during a complex series of chemical reactions involving sunlight, water vapor, and other gases.
These acid aerosols may then fall slowly to the Earth, or they may adhere to cloud droplets or fog droplets (acid fog)
They may even act as nuclei on which the cloud droplets begin to grow. When precipitation occurs in the cloud, it carries the acids to the ground
Occurrence and Extent of Acid Deposition
Precipitation is naturally somewhat acidic. The carbon dioxide in the air dissolves in precipitation, making it slightly acidic with a pH between 5.0 and 5.6
However, precipitation is becoming increasingly acidic in many parts of the world, especially downwind of major industrial areas
Airborne studies conducted during the middle 1980s revealed that high concentrations of acid-rain producing pollutants can be carried great distances from their sources
In 1986, for example, scientists discovered high concentrations of pollutants hundreds of miles off the east coast of North America. It is suspected that they came form the industrial East Coast cities.
Acid rain knows no national boundaries!
Regions noticeably affected by acid deposition are: eastern North America, central Europe, and Scandinavia. Sweden contends that most of the emissions responsible for its acid precipitation come from factories in England.
In some cases, acid precipitation occurs naturally, e.g., northern Canada, where natural fires in coal beds produce tremendous quantities of sulfur dioxide
In the northeastern U.S., where emissions of sulfur dioxide are primarily responsible for the acid precipitation, typical pH values range between 4.0 and 4.5
Acid precipitation is not however confined to the northeastern U.S., the acidity of precipitation has increased rapidly during the past 20 years in the southeastern U.S. as well.
Further west, rainfall acidity appears to be on the increase as well. The main cause along the west coast for the increase in the acidity of rain, appears to be the oxides of nitrogen released in automobile exhaust
Some scientists feel that if the U.S. turns more to coal-fired plants, which are among the leading source of sulfur oxide emissions, the problem will worsen
To deal with the problem of acid deposition, the Clean Air Act of 1990 imposed a reduction in the United States emissions of sulfur dioxide and nitrogen dioxide.
Canada has recently imposed new pollution control standards and set a goal of reducing industrial air pollution by 50%
Effects of Acid Deposition
High concentrations of acid deposition can damage plants and water resources (freshwater ecosystems seem to be particularly sensitive to changes in acidity).
Concern centers mainly on areas where interactions with the soil are unable to neutralize the acidic inputs
Studies indicate that thousands of lakes in the United States and Canada are so acidified that entire fish populations may be adversely affected
In an attempt to reduce acidity, lime is being poured into some lakes
About a third of the trees in Germany show signs of a blight that is due in part to acid deposition
Apparently, acidic particles raining down on the forest floor for decades cause a chemical imbalance in the soil that, in turn, causes serious deficiencies in certain elements necessary for the tree's growth
Acid deposition is eroding the foundations of structures in many cities throughout the world.
In Rome, the acidity of rainfall is beginning to disfigure priceless outdoor fountain sculptures and statues
The estimated annual cost of this damage to building surfaces, monuments, and other structures is more than 2 billion dollars
Radiation and the electromagnetic spectrum
solar energy/radiation is part of the electromagnetic spectrum of radiant energy, which travels at the speed of light, it exhibits both electrical and megnetic properties, all objects emit electromagnetic energy (EMR), The EMS is made up of many different forms of electromagnetic energy: radio waves, microwaves, gamma waves, etc., EMR travels in waves and does not need molecules to propogate them- thus, they can move through a vacuum, they can be characterized by their wavelength- the distance measured along a wave from one crest (trough) to the adjacent crest (trough)
Earth's orbit
earth has an elliptical orbit about the sun, average distance to the sun is 150 million km, plane on which the earth orbits about the sun is called the "plane of ecliptic", "perihelion" earth is closest to the sun on january 3rd, "aphelion"- earth is farthest from the sun on July 4th, only 3.4% difference in solar energy receipt, earth's orbit changes over a 100,000 year cycle, by 18 million km- may contribute to glacial and interglacial periods
Direct vs. Indirect rays from the sun
direct provide more heating (more concentrated energy) than do indirect rays
why do direct rays provide more heating?
(1) energy is spread over a larger surface area; and (2) incoming solar radiation (insulation) must pass through more atmosphere
Reasons for the seasons
seasonality, Insulation, sun's altitude, declination, summer solstice, winter solstice, vernal equinox, autumnal equinox,
a reference to the seasonal variations in the sun's rays above the horizon, and the changes in daylength throughout the year
incoming solar radiation
sun's altitude
the angular distance between the horizon and the sun
the latitude that receives direct rays from the sun
summer solstice
June 20-21 at the tropic of cancer- sun's rays directly overhead
winter solstice
December 20-21 at the tropic of capricorn- sun's rays directly overhead
vernal equinox
March 20-21 sun's rays directly overhead at the equator
autumnal equinox
September 22-23 sun's rays directly overhead at the equator
varies throughout the year depending on latitude, except at the equator and on the two equinoxes, all latitudes experience uneven daylength throughout the course of 1 year
at equator: 12 hours of daylight and 12 hours of night
at 40 degrees n/s: 6 hours difference in daylight
at 50 degrees n/s: 8 hours difference in daylight
temperature decreases with height in the troposphere
the distance from the heat source (the ground) increases
and the air becomes less dense (thinner) with height and thus it's ability to absorb and radiate energy lessens with height
average tempertures are lower
diurnat temperature ranges are greater
UV component is greater- sunburn hazard
Summary of the physical factors responsible for seasonality
(1) earth's revolution and rotation; (2) earth's tilt on it's axis; and (3) its sphericity
Net Radiation at the top of the Atmosphere
have positive values of net radiation at lower latitudes, negative values toward the poles, poleward of 36 degrees north and south latitude, values of net radiation are negative-thus, a net loss in energy, thus we have an overall inmbalance in radiant energy from the equator to poles, this leads to atmospheric and oceanic circulations!!!
Heat transfer
always from warmer to cooler objects
conduction, convection, and radiation
the transfer of heat energy by molecular activity- molecule to molecule contact
the transfer of heat energy by the movement of a mass or substance from one place to another
can be transfered through a vacuum
Forms of atmospheric radiant energy
sun (shortwave) and Earth-Atmosphere (longwave)
Sun (shortwave)
ultraviolet, visible, near infrared
Earth-Atmosphere (longwave)
thermal IR, Units are in micrometers (1 micrometer equals one-millionth of a meter)
Basic Radiation laws
all objects emit radiant energy, hotter objects radiate more total energy per unit area than cooler objects, the hotter the radiating body, the shorter the wavelength of maximum radiation, objects that are good absorbers of radiation are good emitters as well, the rate at which solar energy falls on a surface located at the top of the earth's atmosphere is a constant (solar constant), a blackbody
is an object that is perfectly efficient at absorbing and radiating radiation (blackbodies do not exist in nature, but represent an ideal)
Paths taken by insulation
as insulation moves through the atmosphere three things can happen to it: Reflection, Scattering, and absorption
occurs at the interface between two diffeent media when some of the radiation striking the interface is thrown back
the ratio of reflected to incident radiation (an object with albedo of 1 or 100% is a perfect reflector)- light colored objects have high albedos; darker objects have low albedos
dispersal of radiation in all directions
Direct insulation
insulation that is transmitted directly through the atmosphere to the earth's surface
Diffuse Insulation
insolation that is scattered or reflected to the earth's surface
Distributions of Insulation
the earth- atmosphere energy system is in a state of balance I.O.W. the earth and atmosphere must return to space as much energy as they take in- otherwise the earth's averrage surface temperature would change
Budget: 100 units of Insulation
30 units....reflected to space by clouds, the earth, and the atmosphere (thus the albedo for the earth as a whole (plantary albedo)) is 30%
20 Uunits... absorbed by clouds and the atmosphere
50 units... absorbed at the earth's surface
70 units... radiated back to space by the Earth-Atmosphere system
the earth maintains a delicate balance between incoming and outgoing energy, and essentially there is no yearly gain or loss of total energy, thus the average temperature of the earth remains fairly constant from year to year. In contrast the earth's surface receives a surplus of energy, while the atmosphere exhibits a deficit
The (Atmospheric) Greenhouse Effect
while the earth behaves like a blackbody- the atmosphere does not!!1
The gases that comprise the atmosphere are "selective absorbers"- they absorb some wavelengths and are transparent to others
selective absorbers usually emit radiation at the same wavelength which they selectively absorb at.
Important Selective Absorbers
water vapor, carbon dioxide, nitrous oxide, methane, ozone, these gases are poor absorbers of visible (shortwave) radiation, but good absorbers of infared (longwave) radiation
The Greenhouse effect thus works in the following manner
direct and diffuse shortwave radiation from the sun is absorbed at the earth's surface, the earth radiates longwave energy into the atmosphere where some of it is absorbed by the various greenhouse gases, these gases gain kinetic energy and collide with neighboring air molecules which increases the average KE of the air, which results in an increase of air temperature, these same greenhouse gases also emit longwave radiation-some of whic is transmitted to the earth's surface where it is absorbed and thus heats the ground, the earth then radiates longwave energy upward, where, onece again, it is absorbed by the greenhouse gases and warms the lower atmosphere, and thus, the greenhouse gases act as an "insulating layer" keeping some of the earth's radiant energy from escaping to space; and keeping the lower atmosphere considerably warmer than it would otherwise be.
Temperature measurement and data
air temperature is measured on a regular basis from thermometers mounted in an "insturment shelter"
Those shelters, keep the thermometer from direct sunlight, and allow for a free flow of air
max and min temperature thermometers are usually mounted in the shelter as well
Daily radiation curves and temperatures
the daily variation in air temperature is controlled (primarily) by insulation
when insulation exceeds outgoing longwave, the air temperature rises; when outgoing longwave exceeds insulation, the temperature falls
As insulation input decrease toward the sunset, the energu lost (longwave) exceeds the energy input (insulation)- temperatures begin to drop
(the warmest time of the day occurs not at the moment of maximum insulation (solar noon), but at the moment when a maximum of insulation is absorbed)
the warmest time of the day thus occurs 3-4 hours after solar noon- lag between peak insulation and maximum temperature
Temperature Controls
and factor that causes air temperature to vary from place to place and from time to time
insulation receipt is the most important influence on temperature variations
recall that direct insulation is more concentrated (provides more heating) than oblique insulation; and the equatorial areas are the only latitudes to receive direct insulation
thus, there is a decrease in insulation/heating/temperature from the equatorial regions northward and southward toward the poles
from the equator poleward: continually warm; seasonally variable; always cold
Cloud Cover
cloud type, height, and thickness determine how insolation is reflected
low thick clouds have albedo of 90%
high, think (ice crystal) clouds have albedo of 50%
clouds are moderating influences on temperature- they produce lower daily maximum temperatures and higher nightime minimums
clouds result in slightly lower earth- atmosphere system temperatures
Land-Water Heating Differences
more modeate, marine, continental
more moderate (less extreme)
temperature patterns are associated with water bodies vs. land masses
marine (maritime)
locations that are dominated by the moderating effects of the ocean- they exhibit a smaller range of diurnal and annual temperatures than continental locataions
Continental (continentality)
stations that lack the temperature- moderting effects of large water bodies- they exhibit a greater range of diurnal and annual temperatures than maritime locations
Land-Water temperature controls:
evaporation, transmissibility, specific heat, and mixing
over water surfaces more of the net radiation (NET R) is expended for evaporation- thus, less energy is avaliable for sensible heating
in water, light penetrates to a greater depth, and thus the heat energy is spread over a larger area
over land, the energy is concentrated and contained in the top most layer, and thus higher temperatures are achieved there
Specific Heat
water requires more heat energy to raise its temperatures than does land
Mixing (movement)
the movement of water (currents and movement due to density differences) causes the available heat to be spread over a larger area; heat energy is redistributed
the effects of currents and sea temperatures
influence the temperatures of adjacent land masses
connect locations having the same temperature- show temperature patterns

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