Geography 101: Geography 101: Physical GeographyPhysical Geography

Dr. Kevin LawDr. Kevin Law

Chapter 1Chapter 1

Introduction to EarthIntroduction to Earth

Geography as a Field of LearningGeography as a Field of Learning

Geography- generalized discipline that Geography- generalized discipline that focuses on Earthfocuses on Earth– Greek for “earth description”Greek for “earth description”– Fundamental questionsFundamental questions

““Why is What Where?”Why is What Where?” ““So What?”So What?”

Geography as a Field of LearningGeography as a Field of Learning

Geography’s basic characteristics:Geography’s basic characteristics:– How things differ from place to placeHow things differ from place to place– Has no body of facts it can call wholly its ownHas no body of facts it can call wholly its own– Broad field of inquiryBroad field of inquiry– Both a physical and a social scienceBoth a physical and a social science– Interested in InterrelationshipsInterested in Interrelationships

Physical GeographyPhysical Geography Cultural GeographyCultural Geography

Figure 1-1Figure 1-1

The Environmental SpheresThe Environmental Spheres

Earth’s surface is a complex interface where Earth’s surface is a complex interface where 4 spheres meet.4 spheres meet.– Lithosphere- Lithosphere- litholitho is Greek for “stone” is Greek for “stone”– Atmosphere- Atmosphere- atmo atmo is Greek for “air”is Greek for “air”– Hydrosphere- Hydrosphere- hydro hydro is Greek for “water”is Greek for “water”– Biosphere- Biosphere- bio bio is Greek for “life”is Greek for “life”

The Solar SystemThe Solar SystemFig. 1-7Fig. 1-7

Solar SystemSolar System- system of 8 - system of 8 planets revolving around the planets revolving around the SunSun– Pluto is a dwarf planetPluto is a dwarf planet

Sun- medium sized star & Sun- medium sized star & makes 99% of the solar makes 99% of the solar system’s masssystem’s mass

Sun is 1 of 100 billion stars in Sun is 1 of 100 billion stars in Milky Way galaxy, which is 1 of Milky Way galaxy, which is 1 of a billion galaxiesa billion galaxies

The Solar SystemThe Solar System

Earth’s orbit is nearly the same plane as the Earth’s orbit is nearly the same plane as the other planets (except Pluto (demoted in other planets (except Pluto (demoted in 2006))2006))

Earth, like the Sun, rotates from west to east Earth, like the Sun, rotates from west to east on its axison its axis

Why is Pluto not a planet?Why is Pluto not a planet?

Article Is Pluto a Planet?Is Pluto a Planet? Clip Clip 2

Figure 1-9Figure 1-9

The Size and Shape of the EarthThe Size and Shape of the Earth

Frame of reference determines whether Frame of reference determines whether Earth is “large” or “small”Earth is “large” or “small”

Earth is “oblate spheroid” rather than a Earth is “oblate spheroid” rather than a spheresphere– Greeks believed Earth was a sphere 6Greeks believed Earth was a sphere 6 thth century century

B.C.B.C. Earth shape affected byEarth shape affected by

– Bulges in midriff (pliability of lithosphere)Bulges in midriff (pliability of lithosphere)– Topographical irregularities (relatively small)Topographical irregularities (relatively small)

Figure 1-10 and 1-11Figure 1-10 and 1-11

The Geographic Grid (Fig. 1-12)The Geographic Grid (Fig. 1-12)

System of accurate System of accurate location is necessary location is necessary to pinpoint the position to pinpoint the position of any spot on Earthof any spot on Earth– Grid system- uses Grid system- uses

network of intersecting network of intersecting lineslines

– Graticule-Graticule- grid system grid system for mapping Earth that for mapping Earth that uses parallels and uses parallels and meridiansmeridians

The Geographic GridThe Geographic GridFig. 1-13Fig. 1-13

– 4 Earth features provide reference 4 Earth features provide reference pointspoints North PoleNorth Pole South PoleSouth Pole Rotation axisRotation axis Equatorial planeEquatorial plane

– Equator- Equator- imaginary midline of Earthimaginary midline of Earth

The Geographic GridThe Geographic GridFig. 1-14Fig. 1-14

– Great Circle-Great Circle- largest circle largest circle that can be drawn on a that can be drawn on a sphere, passes through sphere, passes through centercenter Circle of Illumination-Circle of Illumination-

circle that divides Earth circle that divides Earth between light and darkbetween light and dark

– Small Circle-Small Circle- plane that cuts plane that cuts through spherethrough sphere

LatitudeLatitudeFig. 1-15Fig. 1-15

Latitude-Latitude- distance distance measured north and measured north and south of the equatorsouth of the equator

Length of 1 degree Length of 1 degree latitude varies because latitude varies because of polar flatteningof polar flattening

ParallelParallel- an imaginary - an imaginary line that connects all line that connects all points of the same points of the same latitudelatitude

Key “Latitudes”Key “Latitudes”Fig. 1-17Fig. 1-17

Equator, 0Equator, 0°° North Pole, 90°NNorth Pole, 90°N South Pole, 90°SSouth Pole, 90°S Tropic of Cancer, 23.5°NTropic of Cancer, 23.5°N Tropic of Capricorn, 23.5°STropic of Capricorn, 23.5°S Arctic Circle, 66.5°NArctic Circle, 66.5°N Antarctic Circle, 66.5°SAntarctic Circle, 66.5°S

Length of Degrees of Latitude Length of Degrees of Latitude and Longitudeand Longitude

LongitudeLongitudeFig. 1-20Fig. 1-20

Longitude-Longitude- distance distance measured east and west measured east and west

Meridian- Meridian- imaginary line of imaginary line of longitude extending from longitude extending from pole to polepole to pole– NOT parallel to each NOT parallel to each

otherother Prime meridian- Prime meridian- passes passes

through Royal Observatory through Royal Observatory at Greenwich, Englandat Greenwich, England

Figures 1-21, 1-22, and 1-23Figures 1-21, 1-22, and 1-23

Earth-Sun RelationsEarth-Sun Relations

Relationship between Earth and Sun vital Relationship between Earth and Sun vital because dependent on solar energybecause dependent on solar energy

2 Basic Movements:2 Basic Movements:– Earth’s daily rotation on its axisEarth’s daily rotation on its axis– Earth’s annual revolution around the SunEarth’s annual revolution around the Sun

Earth’s Rotation on Its AxisEarth’s Rotation on Its Axis

Earth rotates toward the east (24 hrs)Earth rotates toward the east (24 hrs)– Creates illusion celestial bodies rise in the east and set Creates illusion celestial bodies rise in the east and set

in the westin the west Speed of rotation varies from place to place, but Speed of rotation varies from place to place, but

constant at a given place, so humans cannot constant at a given place, so humans cannot sensesense

Rotational effects:Rotational effects:– Coriolis effect- apparent deflection to rightCoriolis effect- apparent deflection to right– Locations experience increased/decreased gravitational Locations experience increased/decreased gravitational

pull of Moon and Sunpull of Moon and Sun– Daily alternation of light and darknessDaily alternation of light and darkness

Speed of Rotation of Earth’s Speed of Rotation of Earth’s SurfaceSurface

Earth’s Revolution around the SunEarth’s Revolution around the Sun

Tropical Year- time Earth makes 1 revolution Tropical Year- time Earth makes 1 revolution around the Sun (approx. 365.25 days)around the Sun (approx. 365.25 days)

Earth’s revolution is an ellipseEarth’s revolution is an ellipse– Varying Earth-Sun distance does NOT affect seasonal Varying Earth-Sun distance does NOT affect seasonal

temperaturestemperatures– Perihelion- Perihelion- point Earth is closest to Sunpoint Earth is closest to Sun

~147 million km (Jan.3)~147 million km (Jan.3)

– Aphelion-Aphelion- point Earth is farthest from Sun point Earth is farthest from Sun ~152 million km (July 4)~152 million km (July 4)

Figure 1-25Figure 1-25

The Annual March of the SeasonsThe Annual March of the Seasons

Plane of the ecliptic- Plane of the ecliptic- imaginary plane that imaginary plane that passes through the Sun and through every passes through the Sun and through every point of Earth’s orbitpoint of Earth’s orbit

Inclination- Inclination- degree Earth’s rotation axis is degree Earth’s rotation axis is tilted (23.5tilted (23.5°)°)

Polarity-Polarity- Earth’s axis always points toward Earth’s axis always points toward Polaris, the North StarPolaris, the North Star

Insolation- Insolation- Incoming Solar RadiationIncoming Solar Radiation

Figure 1-27Figure 1-27

SolsticesSolstices

Solstice- Solstice- Occurs twice per year when Sun’s rays strike Occurs twice per year when Sun’s rays strike northernmost/southernmost latitudes (23.5northernmost/southernmost latitudes (23.5°N/S)°N/S)– Winter solstice, around Dec. 21Winter solstice, around Dec. 21– Summer solstice, around June 21Summer solstice, around June 21

Tropic of Cancer- Tropic of Cancer- 2323.5.5°N, perpendicular rays (Jun 21)°N, perpendicular rays (Jun 21) Tropic of Capricorn- Tropic of Capricorn- 2323.5.5°S, perpendicular rays (Dec 21)°S, perpendicular rays (Dec 21) Arctic Circle- Arctic Circle- 66 66.5.5°N, 24 hrs of daylight (Jun 21) or °N, 24 hrs of daylight (Jun 21) or

darkness (Dec. 21)darkness (Dec. 21) Antarctic Circle- Antarctic Circle- 6666.5.5°S, 24 hrs of daylight (Dec 21) or °S, 24 hrs of daylight (Dec 21) or

darkness (Jun 21)darkness (Jun 21)

EquinoxesEquinoxes

Equinox- Equinox- perpendicular Sun rays strike the perpendicular Sun rays strike the equator (12 hrs daylight)equator (12 hrs daylight)– Vernal Equinox, Vernal Equinox, March 20March 20– Autumnal Equinox, Autumnal Equinox, Sep 22Sep 22

Figure 1-28Figure 1-28

Changes in Daylight and DarknessChanges in Daylight and Darkness

Period of daylight vary throughout yearPeriod of daylight vary throughout year– Increasing north of the equator from Winter Increasing north of the equator from Winter

solstice to Summer solstice (Northern Hem.)solstice to Summer solstice (Northern Hem.)

Day length and Sun ray angle determine Day length and Sun ray angle determine insolation amountinsolation amount– Tropic latitudes are warm because of high sun Tropic latitudes are warm because of high sun

anglesangles– Polar regions cold because of low sun anglesPolar regions cold because of low sun angles

Day Length at Time of June Day Length at Time of June SolsticeSolstice

Telling Time- Standard TimeTelling Time- Standard Time

Use of local solar time created problemsUse of local solar time created problems 1884 international conference divided world 1884 international conference divided world

into 24 standard time zones, 15into 24 standard time zones, 15° long. each° long. each– Universal Time Coordinated (UTC)-Universal Time Coordinated (UTC)- formerly formerly

Greenwich Mean Time (GMT); uses local solar Greenwich Mean Time (GMT); uses local solar time of Greenwich as standardtime of Greenwich as standard

Figure 1-31Figure 1-31

Figure 1-32Figure 1-32

The International Date LineThe International Date LineFig. 1-34Fig. 1-34

International Date International Date Line-Line- marks where marks where new days begin and new days begin and old days exitold days exit– Time difference of 1 Time difference of 1

day from one side to day from one side to otherother

– Falls on 180Falls on 180thth meridian meridian

Daylight-Saving TimeDaylight-Saving Time

Clocks are set forward 1 hr to extend Clocks are set forward 1 hr to extend daylight into eveningdaylight into evening– Originally created in Germany to conserve Originally created in Germany to conserve

electricityelectricity– AZ, HI do not observeAZ, HI do not observe– Was not designed for farmers Was not designed for farmers

After all it makes it darker in the morningAfter all it makes it darker in the morning