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This Course

• Physics, Geology, Meteorology, and Astronomy

• Attempts to describe the physical world in which we live

• Measurements – movement, temperature, weather conditions, time, etc.

• Constant use of measurements – many examples in book.

• Can everything be measured w/ certainty??• As smaller and smaller objects were

measured it became apparent that the act of measuring distorted the object.

Section 1.1


Scientific Law

• Scientific Law – after a series of experiments a concise statement (words/math) about a relationship/regularity of nature

• Example – Law of Conservation of Mass (no gain or loss during chemical reaction)

• The law simply states the finding, but does not explain the behavior.

Section 1.2


Hypotheses

• Hypothesis – tentative explanation(s) of the relationship/regularity in nature

• Example: Matter consists of small particles (atoms) that simply rearrange themselves

• A good hypothesis must suggest new experiments that serve to test its validity.

• The hypothesis is supported if it correctly predicts the experimental results

Section 1.2


Theory

• Theory – tested explanation for a broad segment of basic natural phenomena

• Example: Atomic Theory – This theory has withstood testing for 200+ years and continues to correctly predict atomic behavior.

Section 1.2


Standard Units and Systems of Units

• Expressed in magnitude and units• Fundamental Physical Quantities –

length, mass, time, and electric charge• Standard Unit – fixed and reproducible

value to take accurate measurements

Section 1.4


Standard Units and Systems of Units continued…

• Two major systems of units• British (English) system – only used

widely in the United States (miles, inches, pounds, seconds, etc.)

• International System of Units (Metric system) – used throughout most of the world (kilometers, meters, grams, etc.)

• The U.S. “officially” adopted the metric system in 1893, but continues to use the British system.

Section 1.4


Metric System

• Uses acronym “mks system” from standard units of length, mass, and time – meter, kilogram, second

• It is a decimal (base-10) system – this is much better than the British system

• Administered by -- Bureau International des Poids et Mesures (BIPM) in Paris

• International System of Units (SI)

• Contains seven base unitsSection 1.5


Modern Metric System (SI)

• The base units are a choice of seven well-defined units which by convention are regarded as dimensionally independent: – meter, m (length)– kilogram, kg (mass)– second, s (time)– ampere, A (electrical current)– kelvin, K (temperature)– mole, mol (amount of a substance)– candela, cd (luminous intensity)

Section 1.5


Base-10 Convenient

• Easy expression and conversion• Metric examples vs. British examples

– 1 kilometer = 1000 meters– 1 mile = 5280 feet– 1 meter = 100 centimeters– 1 yard = 3 feet or 36 inches– 1 liter = 1000 milliliters– 1 quart = 32 ounces or 2 pints– 1 gallon = 128 ounces

Section 1.5


Unit Combinations

• When a combination of units becomes complex and frequently used it is given a name. Examples:– newton (N) = kg x m/s2

– joule (J) = kg x m2/s2 – watt (W) = kg x m2/s3

Section 1.6


Significant Figures

• Significant figures (“SF”) – a method of expressing measured numbers properly

• A mathematical operation, such as multiplication, division, addition, or subtraction cannot give you more significant figures than you start with.

• For example, 6.8 has two SF and 1.67 has three SF.

Section 1.7


• When we use hand calculators we may end up with results like: 6.8/1.67 = 4.0718563

• Are all these numbers “significant?”

Section 1.7


Rounding off Numbers – Examples

• Round off 0.0997 to two SF

• 0.0997 0.10

• What about this? 5.0 x 356 = 1780

• Round off 1780 to 2 SF

• 1780 1800

Section 1.7


Powers-of-10 Notation (Scientific Notation)

• Many numbers are very large or very small – it is more convenient to express them in ‘powers-of-10’ notation

• 1,000,000 = 10x10x10x10x10x10 = 106

Section 1.7

000,000,1

1610

1 = = 0.000001 = 10-6


Scientific Notation

10000 = 10 x 10 x 10 x 10 = 104

1000 = 10 x 10 x 10 = 103

100 = 10 x 10 = 102

10 = 101

1 = 100


Scientific Notation

0.1 = 1/10 = 1/101 = 10-1

0.01 = 1/100 = 1/102 = 10-2

0.001 = 1/1000 = 1/103 = 10-3

0.0001 = 1/10000 = 1/104 = 10-4


Scientific Notation

• The distance to the sun can be expressed many ways:– 93,000,000 miles– 93 x 106 miles– 9.3 x 107 miles– 0.93 x 108 miles

• All four are correct, but 9.3 x 107 miles is the preferred format.

Section 1.7


Cartesian Coordinates

• A two-dimensional system is one in which two lines are drawn perpendicular with an origin assigned at the point of intersection.

Horizontal line = x-axis

Vertical line = y-axis• The system we commonly use is the

Cartesian coordinate system, named after the French philosopher/mathematician René Descartes (1596-1550).


Cartesian Coordinates – Two Dimensional

• x number gives the distance from the y-axis.• y number gives the distance from the x-axis.• Many cities are laid out in a Cartesian pattern

with streets running N-S & E-W.

We want to be able to determine locations on earth and in space.


Latitude

• Latitude - the angular measurement in degrees north and south of the equator

• The latitude angle is measured from the center of the earth relative to the equator.

• Lines of equal latitude are circles drawn on the surface and parallel to the equator.


Longitude

• Longitude is the angular measurement, in degrees, east or west of the reference meridian, the Prime Meridian (0o) at Greenwich, England.– A large optical

telescope was located there.

• Maximum value of 180o E or W


Time

• Time - the continuous forward flowing of events

• The continuous measurement of time requires the periodic movement of some object as a reference.

• The second has been adopted as the international unit of time.

• Vibration of the cesium-133 atom now provides the reference of a second – 9,192,631,770 cycles per second


Days

• Apparent Solar Day – the elapsed time between two successive crossings of the same meridian (line of longitude) by the sun (361o)

• Sidereal Day – the elapsed time between two successive crossings of the same meridian by a star other than the sun (360o)


Diagrams of Sun's Position (Degrees Latitude) at Four Different Times of the Year


Two Different Years

• Tropical Year – the time interval from one vernal equinox to the next vernal equinox – 365.2422 mean solar days– The elapsed time between 1 northward crossing of

the sun above the equator to the next northward crossing.

• Sidereal year – the time interval for earth to make one complete revolution around the Sun with respect to any particular star other than the sun – 365.2536 mean solar days– 20 minutes longer than the tropical year


Gregorian Calendar

• The Julian calendar was fairly accurate and was used for over 1500 years.

• In 1582 Pope Gregory XIII realized that the Julian calendar was slightly inaccurate.– The Vernal Equinox was not falling on March 21.

• A discrepancy was found. To correct this the Pope decreed that 10 days would be skipped.

• 365.2422 not 365.25 = discrepancy• Every 400 years 3 leap years would be

skipped.• This is the calendar we use today.


The Solar System

• The solar system - complex system of moving masses held together by gravitational forces

• Sun is center

• Sun is the dominant mass

• Revolving around the sun -- 8 planets, over 70 moons, 1000’s of other objects (asteroids, comets, meteoroids, etc.)


Johannes Kepler (1571-1630)

• German mathematician and astronomer

• Kepler’s 1st Law – Law of Elliptical Paths – All planets move in elliptical paths around the sun with the sun as one focus of the ellipse

• An ellipse is a figure that is symmetric about two unequal axes


Kepler’s Second Law

• Law of Equal areas – An imaginary line (radial vector) joining a planet to the sun sweeps out equal areas in equal periods of time


Kepler’s Third Law

• Harmonic Law – the square of the sidereal period of a planet is proportional to the cube of its semimajor axis

• T2 = k R3

• T = period (time of one revolution)

• R = length of semimajor axis

• k = constant (same for all planets) = 1y2/AU3

Copyright © Houghton Mifflin Company. All rights reserved. 1| 32Copyright © Houghton Mifflin Company. All rights reserved. 16 | 32

Our Solar System

• Sun – 99.87% of the mass of solar system

• Of the remaining 0.13%, Jupiter is > 50%

• Planets with orbits smaller than earth are classified as “inferior”

• Planets with orbits larger than earth are classified as “superior”

Section 16.1


Albedo

• Albedo – the fraction of the incident sunlight reflected by an object

• Earth’s albedo is 33%• Moon’s albedo is 7% (from Earth the

moon is the 2nd brightest object in the night sky)

• Venus’ albedo is 76% (3rd brightest is sky)

• Since the Moon is so close to Earth it is brighter than Venus

Section 16.2


Stellar Parallax

• The observation of parallax is indisputable proof that the Earth revolves around the Sun.

• In addition, the measurement of the parallax angle is the best method we have of determining the distance to nearby stars

Section 16.2


Terrestrial Planets

• The terrestrial planets include: Mercury, Venus, Earth, Mars

• Due to physical/chemical characteristics they resemble Earth

• All four terrestrial planets are – Relatively small in size and composed of rocky

material and metals– Relatively close together and close to Sun– Have no rings– Only Earth and Mars have moons– Only Earth has surface water and oxygen

Section 16.3


The Jovian Planets

• Jupiter, Saturn, Uranus, Neptune • Much larger than the terrestrial planets• Composed mainly of hydrogen and helium

– The four Jovian planets have a very low average density (approximately 1.2 g/cm3)

• All four are thought to have a rocky core composed of iron and silicates

• Thick layers of frozen methane, ammonia, and water are found above the core

Section 16.4


Terrestrial versus Jovian

• relatively small in mass and size

• composed of rocky material and metals (having a core mostly of iron and nickel)

• relatively dense (~5 g/cm3)

• solid surfaces • weak magnetic fields• no ring systems

• relatively large in mass and size

• composed mainly of hydrogen and helium (rocky core with layers of ice above it)

• low density • (~1.2 g/cm3) • no real surfaces;• strong magnetic fields• many moons and ring

systems


Origin of the Solar System

• Any theory that purports to explain the origin and development of the solar system must account for its present form

• According to our best measurements, our solar system has been in its present state for about 4.5 billion years

• A valid theory for solar system formation – must be able to explain a number of major properties of our solar system

Section 16.5


The Formation of the Solar SystemCondensation Theory

Section 16.5


The Moon

• Second brightest object in the sky• “moon” – unknown origin of the word• Many primitive and modern societies

base their religious ceremonies on the cycles of the moon (e.g., new and full moons).

• Our month is based on moon’s cycle.• Human ovarian cycle is also

synchronized to the 29.5 day lunar cycle.

Section 17.1


Characteristics of the Moon

• Nearly spherical, with a diameter of 3476 km (2160 mi) – approx. ¼ the earth’s diameter

• Mass of the moon = 1/81 of the earth• Average density of 3.3 g/cm3 (earth is 5.5)• Surface gravity of the moon is only one-sixth

of Earth’s.• Therefore one’s weight on the moon would

only be one-sixth of that on Earth.• Average reflectance (albedo) = only 7%

(only 7% of the light received from the sun is reflected)

Section 17.1


Inside the Moon


Origin of the Moon??

• Must take into account these facts:• Lunar rocks are similar to the earth’s mantle.• Oxygen isotope ratios indicate that the earth

and the moon were formed at a similar distance from the sun.

• There is no water in lunar rocks.• There is a deficiency of volatile elements

(which were driven off by heat).• Relative to earth, moon has less iron.• 3.3 g/cm3 = moon; 5.5 g/cm3 = earth• The oldest rocks on earth and moon are

similar.Section 17.1

Copyright © Houghton Mifflin Company. All rights reserved. 17 | 44

Origin of the Moon

• Most widely accepted theory is the great impact theory.

• A planet-sized object (size of Mars) struck the earth with a glancing blow 4.4 billion years ago, resulting in the ejection of matter into orbit to form the moon.

Section 17.1

Relative Motions of the Moon and Earth

Section 17.2


New Phase or New Moon• Occurs when

earth, sun, and moon are all in the same plane, with the moon positioned between the Sun and Earth

• At this position, the dark side of the moon is fully toward the Earth (“dark of the moon”).

Section 17.2


Positions of the Sun, Moon, and Earth During a Total Solar Eclipse

The umbra and penumbra are, respectively, the dark and semidark shadows cast on the Earth by the Moon

Section 17.2


A Lunar Eclipse

Section 17.2


Tidal BulgesThe two tidal bulges result in two high tides and two

low tides daily

Section 17.2


Spring and Neap Tides

Section 17.2


Asteroids or Minor Planets

Section 17.5


The Sun

• Star - a self-luminous sphere of hot gases, energized by nuclear reactions and held together by the force of gravity.

• The Sun is the nearest star to Earth.• The Sun is enormous in size relative to

the size of Earth.– The Sun’s diameter is approximately 4

times the distance between the Earth and the Moon.

Section 18.1


Structure and Composition of the Sun

• The Sun can divided into four concentric layers:– Core - the innermost part of the Sun where

nuclear fusion occurs– Photosphere - the “surface” that we see– Chromosphere – the layer of very hot

gases above the photosphere, also known as the Sun’s lower atmosphere

– Corona - the Sun’s outer atmosphere

Section 18.1


Radial Cross Section of the Sun

The boundary between any two layers is not sharply defined.

Section 18.1


Interior of the Sun

• The Sun’s interior is so hot that individual atoms cannot exist.– Continuous high-speed collisions result in the

separation of nuclei and electrons.• A fourth phase of matter, called a plasma, is

created where nuclei and electrons exist as a high-temperature gas.

• The temperature at the central core of the Sun is 15,000,000 K and the density is 150 g/cm3.– The innermost 25% of the Sun, the core, is where

H is consumed to form He.

Section 18.1


Proton-Proton Chain

• In the net reaction of the PP Chain, four protons form a He nucleus, two positrons, two neutrinos, and two gamma rays.

• The amount of energy released by the conversion of mass conforms with Einstein’s equation, E = mc2 .

Section 18.1


The Celestial Sphere

• Celestial sphere – the huge imaginary sphere of the sky on which all the stars seem to appear

• During any given night, the great dome of stars appear to progressively move westward, from an observer’s vantage point on Earth.

• North celestial pole (NCP) – the point in the Northern Hemisphere that the stars seem to rotate around– Polaris or the “North Star”

• South celestial pole (SCP) – the point in the Southern Hemisphere that the stars seem to rotate around

Section 18.2


Celestial Sphere

• Because of the 23.5o tilt of the Earth’s rotational axis, the ecliptic & celestial equator are inclined to one another, these two planes intersect at only two points.

Section 18.2


Celestial Prime Meridian

• Celestial prime meridian – the half-circle created by the intersection of the NCP, the vernal equinox, and the SCP

• The celestial prime meridian is therefore a reference line or starting line used to measure celestial longitude.

Section 18.2


Celestial Longitude & Latitude

• The measure of celestial longitude is called the right ascension (RA) of the star or galaxy.

• The RA is the position of the star/galaxy to the east of the celestial prime meridian.– Measured in “hours, minutes, and seconds” with

the full circle having a total of 24 hours

• The declination (DEC) of a star or galaxy is an angular measurement (in degrees, minutes, and seconds) north or south of the celestial equator.

Section 18.2


Celestial Distance

• The distance to most celestial bodies is measured in astronomical units (AU), light-years, or parsecs.

• Astronomical unit (AU) – the mean distance between the Earth and the Sun (1.5 x 108 km)

• Light-year (ly) – the distance light travels through a vacuum in one year (9.5 x 1012 km)

• Parsec (pc) – distance to a star when the star exhibits a parallax of 1 second of arc

(3.26 ly = 3.09 x 1013 km)

Section 18.2


Celestial Magnitude

• The Greek astronomer and mathematician Hipparchus was a dedicated observer of the stars.

• He compiled the first star catalog by measuring the location and assigning apparent brightness magnitudes to more than 800 stars.

• Apparent magnitude – the brightness of any celestial object as observed from Earth– First magnitude stars were the brightest and sixth

magnitude stars were barely visible to the unaided eye.

Section 18.3


Apparent Magnitude

• The apparent magnitude scale in use today is a modified version of Hipparchus’ scale.– Instruments are used to accurately measure and

quantify the apparent magnitudes.

• The modern scale is constructed such that a difference of 5 magnitudes represents a difference of 100 in apparent brightness.– Therefore a first-magnitude star appears 100

times brighter than a sixth-magnitude star.

Section 18.3


Apparent Magnitude of other Celestial Bodies

• The brightest celestial body is the Sun. – The Sun has an apparent magnitude of –27.

• The full moon is the second brightest celestial body.– The full moon has an apparent magnitude of –13.

• Venus is the brightest planet.– Venus has an apparent magnitude of –4.

• Sirius is the brightest star. (8.7 ly in distance)– Sirius has an apparent magnitude of –1.

Section 18.3


Absolute Magnitude

• Obviously, a star’s distance from Earth tremendously affects its apparent brightness.

• Absolute magnitude – the brightness a star would have if it were placed 10 pc (32.6 ly) from Earth

• Our Sun, for example, has an absolute magnitude of +5.

• If we know the distance to a star and its apparent magnitude, the absolute magnitude can be calculated.

Section 18.3


The H-R (Hertzsprung-Russell) Diagram

• The H-R Diagram results from plotting the stars’ absolute magnitudes versus the temperatures of their photospheres.

• Most stars become brighter as they get hotter.

• These stars plot as a narrow diagonal band in the diagram.

• The hottest (and generally brightest) stars are blue. The coolest (and generally least bright) stars are red.

Section 18.3


Hertzsprung-Russell Diagram

Note that some stars do not fall along the main sequence.

Section 18.3


Stellar Evolution on the H-R Diagram

Section 18.4


Evolution of a low-mass starProtostar, main-sequence star, red giant, planetary nebula, and white dwarf

Section 18.4


High-Mass vs. Low-Mass Stars

• High-mass stars and low-mass stars form initially in similar manners.

• High-mass stars are hotter and brighter than low-mass stars.– High-mass star move onto the main

sequence at higher points.

• High-mass stars do not stay on the main sequence as long as low-mass stars, due to their higher rate of thermonuclear fusion.

Section 18.5


Evolution of a High-Mass Star

When high-mass stars moves off the main sequence they become red supergiants and eventually explode as Type II supernovae. Much of the material is scattered into space leaving behind a neutron star or black hole.

Section 18.5


Galaxies

• Galaxy – a very large aggregate of stars, gas, and dust held together by their mutual gravitational attraction

• Galaxies are considered to be fundamental components of the universe.

Section 18.6


The Milky Way GalaxyFace-on and edge-on Views of our Galaxy

Section 18.6


Hubble & Spectrum Shifts

• Hubble examined the spectral shifts of different galaxies.

• During his investigations he noted that some shifts were blue and some red.– The blue shift indicates that the galaxy is

moving toward us.– The red shift indicates that the galaxy is

moving away from us.

Section 18.7


Expanding Universe

• Hubble noticed that far-away galaxies all exhibited red shifts.

• He also noted that the farther away the galaxy, the larger the red shift.

• As a result, Hubble concluded that the universe must be expanding.

Section 18.7


Hubble’s Law

The greater the distance, the greater the recessional velocity (calculated from the observed red shift)

Section 18.7


Hubble’s Law

• Hubble’s Law – the recessional speed of a distant galaxy is directly proportional to its distance from the Milky Way galaxy

• v = Hd– v = recessional velocity of the galaxy– d = distance away from us– H = the Hubble constant

• H has not been precisely established yet but lies somewhere between 50 and 80 km/s per million parsecs, depending on what galaxies are being observed and what experimental techniques are used.

Section 18.7


Consequence’s of Hubble’s Law

• What does it mean if all the other galaxies are all receding from away from us?

• We must be at the center of the universe – No!

• Almost all astronomers agree that we live in an ever expanding universe.

• Therefore, every galaxy is receding from every other galaxy.– An observer, from anywhere in the universe would

witness the same phenomena – receding galaxies.

Section 18.7


Rising Bread Analogy of the Expanding Universe

• The raisins represent galaxies and the dough represents space. As the loaf of bread rises, every raisin recedes from every other raisin.

• The greater the initial distance from a given raisin, the faster and farther the other raisins move

Section 18.7


The Big Bang – Broad Acceptance

• Experimental evidence supports the Big Bang in three major areas:

• Cosmological redshift – galaxies today have a redshift in their spectrum lines

• Cosmic microwave background – microwave radiation that fills all space and is thought to represent the redshifted glow from Big Bang

• There is a H to He mass ratio of 3 to 1 in the stars and interstellar material, as predicted by the Big Bang model.

Section 18.7


Composition of the Atmosphere

• The air of our atmosphere is composed of a mixture of gases and holds varying amounts of suspended liquid droplets and solid particles

• Only two gases, nitrogen and oxygen, make up close to 99%, by volume, of air near the Earth– Both of these dominant gases are diatomic - N2 & O2

• Argon (Ar, 0.9%) and carbon dioxide (CO2, 0.03%) are the other major constituents of air

• Very small quantities of many other gases are found in the atmosphere

Section 19.1


Temperature

• Major recognizable divisions within the atmosphere can be distinguished based on vertical temperature variations

• Vertically, Earth’s atmosphere is divided into four temperature regions– Troposphere – ground to about 16 km (10 mi)– Stratosphere – 16 km to about 50 km (10 – 30 mi)– Mesosphere – 50 km to about 80 km (30 – 50 mi)– Thermosphere – 80 km to outer space

Section 19.1


Vertical Structure of the Atmosphere

• Major divisions of the atmosphere based on temperature variations


Insolation Distribution

• Insolation is affected by a number of different processes as it arrives and transects the Earth’s atmosphere

• Note that only about 50% of the total insolation actually reaches the Earth’s surface

Section 19.2


Albedo

• Albedo – the amount of light a body reflects• Of the insolation received by Earth, about

33% is returned to space via reflection and scattering– Therefore the Earth has an albedo of 33%

• The moon only has an albedo of 7% due to its dark surface and lack of atmosphere

• As viewed from space the Earth is much brighter and more impressive than the moon

Section 19.2


The Greenhouse Effect

Section 19.2


Latent Heat of Condensation

• A great deal of evaporation occurs globally due to the insolation that reaches the surface

• Therefore, enormous quantities of latent heat is transferred into the atmosphere as this energy is released during the condensation of the gaseous water into clouds, fog, rain, dew, etc.

Section 19.2


Fundamental Atmospheric Measurements

• Temperature– Air temperature measurements should not

be taken when the thermometer is exposed to direct sunlight

• Pressure

• Humidity

• Wind Speed and Direction

• Precipitation

Section 19.3


Air Motion in the Atmosphere

• Wind – the horizontal movement of air along the Earth’s surface

• Air Currents – vertical movement of air, broken down into updrafts and downdrafts

• Atmospheric gases within the atmosphere are subject to two primary forces– Gravity– Pressure differences due to temperature variations

Section 19.4


IsobarsWind direction will always be at right angles to the isobar and in the direction of the lower pressure

Section 19.4


Earth’s General Circulation Pattern

• Although many local variations occur within the cells, the prevailing winds of this semi-permanent circulation structure are important in influencing general weather movement around the globe

Section 19.4


Condensation

• Water droplets do not form randomly, but form around microscopic foreign particles called hygroscopic nuclei present in the air

• Hygroscopic nuclei may consist of dust, smoke, soot, salt, or other small airborne particles– Since droplets form around these hygroscopic

nuclei, condensation provides a mechanism for cleansing the atmosphere

• If the proper type/size of airborne particles are not present, condensation may not occur or will be retarded

Section 20.1


The Bergeron Process

• The mixing of ice crystals and supercooled water vapor lead to the production of large ice crystals

• These large ice crystals will then melt into large droplets of water in the lower portion of the cloud, coalesce, and fall as precipitation

Section 20.1


Air Masses

• The general weather conditions at any given place depend largely on vast air masses that move across the country

• Air mass – a large body of air that takes on physical characteristics that distinguish it from the surrounding air

• The main physical characteristics the distinguish an air mass are temperature and moisture content

Section 20.2


Air-Mass Source RegionsAir masses that affect North America

Section 20.2


Cold and Warm Fronts• Cold fronts generally form a

sharp, steep boundary where the lighter warm air is displaced upward. As a result, cold fronts are accompanied by more violent and sudden changes in weather.

• Warm fronts form a more gradual boundary because it is more difficult for the lighter warm air to displace the denser cold air.

Section 20.2


Tornadoes

• Tornado – the most violent of storms• Although tornadoes may not be as large

as other storms, its concentrated energy results in great destructive potential

• Tornadoes are most common in the U.S. and Australia

• Most tornadoes in the U.S. occur between the Rockies and Appalachians– April, May, and June are the peak times for

tornadoes in the U.S.

Section 20.3


Tropical Storms

• Tropical storm – a massive weather disturbance that forms over tropical oceanic regions

• Tropical storms are classified as hurricanes once their wind speed exceeds 119 km/h (74 mi/h)

• Hurricane diameters range from 480 to 960 km and their wind speeds range from 118 to 320 km/h

Section 20.3


Temperature Inversion

• Normally the lapse rate near the Earth’s surface decreases uniformly with altitude

• A temperature inversion exists when near the surface the temperature locally increases with increasing altitude

Section 20.4


Air Pollutants and Their Major Sources

• Note that transportation is the largest contributor to air pollution

• The particulates emitted from industrial processes include a number of harmful metals, including Pb and As

• “Stationary sources” refer mainly to power generation plants

Section 20.4


Minerals

• Mineral – a naturally occurring, inorganic, crystalline (solid) substance consisting of one or more chemical elements in fairly specific proportions with a distinctive set of physical properties

• Minerals are around us everywhere – some are quite valuable (diamond, sapphires, emeralds) other minerals are very common (calcite, quartz.)

• Mineralogy – the study of minerals

Section 21.1


Relative Abundance by Mass of Elements in the Earth’s Crust

• Only two elements, O & Si, account for 74% of the elements (by mass) in the Earth’s crust.

Section 21.1

Section 21.1


Identification of Minerals

• Mineral classification is based on both physical and chemical properties.

• This is advantageous because there are some minerals that have the same chemical formula but different molecular structures.

• For example the two minerals graphite and diamond are both made of pure C but they are dramatically different minerals.– Pure diamond is very hard, clear, and crystalline.– Pure graphite is soft and black (dry lubricant and

pencil lead.)

Section 21.1


Physical Properties - Summary

• Crystal form

• Hardness

• Cleavage

• Fracture

• Color

• Streak

• Luster

• Specific gravity


Igneous Rocks

• Igneous rock – a type of rock formed from a molten material that has cooled and solidified

• Magma – molten rock material that originates deep within the Earth– Rocks that solidify from a magma, beneath the

Earth’s surface, are called “intrusive” igneous rocks.

• Lava – molten rock material that reaches the Earth’s surface due to a volcanic eruption– Rocks that solidify from lava, at the surface, are

called “extrusive” igneous rocks.

Section 21.2


Sedimentary Rocks

• Sedimentary rock – rocks that form at or very near the surface of the Earth due to compaction and cementation of sediments

• The sediments that comprise sedimentary rocks come from three general sources:1) Rock fragments due to the erosion of preexisting

(older) rocks

2) Minerals chemically precipitated from solution

3) Plants or animal remains (fossils)

Section 21.2


Metamorphic Rocks

• Metamorphic rock – forms by the alteration of a preexisting rock due to the effects of pressure, high temperature, and/or a chemical change

• Metamorphism generally occurs well below the surface of the Earth but at shallower depths and temperatures than would cause the rock to melt.

Section 21.2


Uniformitarianism

• Beginning with the Scottish physician/scientist James Hutton, scientists started to realize that ancient rocks were formed the same way as modern rocks.– Since they were formed the same way, they can

be interpreted similarly.

• Uniformitarianism – geologic processes occurring today operated similarly in the past and can therefore be used to explain past geologic events– “The present is the key to the past”

Section 21.2


The Rock Cycle

Section 21.2


Plate Tectonics

• The prediction of individual volcanic eruptions is generally not possible.

• However we are aware of specific trends where volcanic eruptions typically do occur.

• Most active volcanoes are located along linear zones, particularly along the margins of the Pacific Ocean.– The so-called “ring of fire”

• The theory of plate tectonics can explain why volcanoes occur where they do.

Section 21.3


Plate Tectonics

• According to the Theory of Plate Tectonics the solid outermost shell of the Earth is called the lithosphere.– The lithosphere is separated into several large and

small fragments, called plates.

• The rigid lithosphere rests or “floats” on a semimolten layer called the asthenosphere.

• We will study plate tectonics in greater detail in the next chapter.

• According to plate tectonics the lithospheric plates slowly move over the semimolten asthenosphere.

Section 21.3


Plate Boundaries

• The lithospheric plates interact with each other in three basic ways:

• Convergent boundary – two plates move towards each other

• Divergent boundary – two plates move away from each other

• Transform boundary – two plates slide past each other

• The vast majority of the volcanoes on Earth occur at convergent boundaries.

Section 21.3


Magma Viscosity

• Magma viscosity, in turn, is dependent on two factors: 1. temperature and 2. silica content

• The higher the temperature the lower the viscosity. (flows easier)– In general magmas that originate deep within the

Earth have higher temperatures.• The higher the silica content the higher the

viscosity. (more difficult to flow)– In general magmas that originate at shallow

depths have a higher silica content.

Section 21.4


Continental DriftFormulation of the Theory

• As one looks at a current world map, it is apparent that the coastlines of eastern South America and western Africa fit together fairly well.

• Is this a coincidence or were these two and the other continents once attached?

• Over the past several hundred years scientists have speculated as to the meaning of this observation. Have the continents drifted?

Section 22.1


Seafloor Spreading

• In 1960, the American geologist Harry Hess suggested a viable mechanism that could explain continental drift.

• At the time the mid-ocean ridge system and the deep sea trenches had been mapped in fair detail throughout the world’s oceans.

• The mid-ocean ridge system was known to stretch throughout the world.

• The trenches were known to be very deep and very long and narrow.

Section 22.1


Plate Tectonics

• We now visualize ocean basins to be in a constant cycle with new crust being created at the mid-ocean ridges and old crust descending along the ocean trenches.

• We also know that the lithosphere is composed of a series of solid segments called plates.

• These plates are constantly moving and interacting with other plates.

• The theory of plate tectonics encompasses all these processes.

• The lithosphere is divided into approximately 20 plates.

Section 22.2


Causes of Earthquakes

• Earthquakes are most likely to occur along plate boundaries.

• Stresses are exerted on the rock formations in adjacent plates, as movement occurs.

• Since rock possess elastic properties, energy is stored until the stresses can overcome the friction between the two plates.

• At the moment of energy release, the rocks along the fault suddenly move, the energy is released, and an earthquake occurs.

Section 22.3


Anatomy of an Earthquake

Section 22.3


Seismograph• During a quake, the spool vibrates and the light beam

is relatively still.

Section 22.3


Seismic Wave Travel Through the Earth’s Interior

• S waves do not travel through the liquid outer core.

• P waves are refracted at density boundaries.

Section 22.3


Fault Terminology Illustrated

Section 22.4


Fossils

• Fossil – any remnant or indication of past life that is preserved in rock

• Paleontology - the study of fossils.– The study of fossils is of great interest to

both geologists and biologists.

• Paleontologists combine present-day biologic information with ancient fossil and rock data to make an interpretation of past events and environments.

Section 24.1


Principle of Superposition

• Principle of superposition – in a sequence of undisturbed sedimentary rocks, lavas, or ash the oldest layer is on the bottom with each ascending layer progressively younger

• In other words, the bottom layer was deposited first and is therefore the oldest layer; the top layer was deposited last and is therefore the youngest layer.

• If the layers have been disturbed (faulted or folded) this must be taken into account.

Section 24.2


Principle of Cross-Cutting Relationships

• Principle of cross-cutting relationships – an igneous rock is younger than the rock layers that it has intruded

• This principle also applies to faults and folds, where the fault or fold is younger than any rocks that are affected.

Section 24.2


Index Fossils

• Index fossils – fossils that are wide-spread in distribution, easily identified, and limited to a particular time segment of the Earth’s history– These fossils can be of major assistance during

the process of correlation.

• Once a particular index fossil has been thoroughly established, geologists immediately know the age of any rocks containing this index fossil anywhere in the world.

Section 24.2


Relative Geologic Time Scale

• Eons are divided into eras.

• There are three eras contained within the Phanerozoic Eon:

• Paleozoic Era – the oldest and “age of ancient life”

• Mesozoic Era – the “age of reptiles”

• Cenozoic Era – the youngest and “age of mammals”

Section 24.2


Geologic Time Scale

• Time is given in millions of years before present, along with major geologic and biologic events

Section 24.5

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