3. Geography as a Field of Learning
Geography- generalized discipline that
focuses on Earth
– Greek for “earth description”
– Fundamental questions
“Why is What Where?”
“So What?”
4. Geography as a Field of Learning
Geography’s basic characteristics:
– How things differ from place to place
– Has no body of facts it can call wholly its own
– Broad field of inquiry
– Both a physical and a social science
– Interested in Interrelationships
Physical Geography
Cultural Geography
6. The Environmental Spheres
Earth’s surface is a complex interface where
4 spheres meet.
– Lithosphere- litho is Greek for “stone”
– Atmosphere- atmo is Greek for “air”
– Hydrosphere- hydro is Greek for “water”
– Biosphere- bio is Greek for “life”
7. The Solar System
Fig. 1-7
Solar System- system of
8 planets revolving
around the Sun
– Pluto is a dwarf planet
Sun- medium sized star &
makes 99% of the solar
system’s mass
Sun is 1 of 100 billion
stars in Milky Way galaxy,
which is 1 of a billion
galaxies
8. The Solar System
Earth’s orbit is nearly the same plane as the
other planets (except Pluto (demoted in
2006))
Earth, like the Sun, rotates from west to east
on its axis
9. Why is Pluto not a planet?
Article
Is Pluto a Planet?
Clip
Clip 2
11. The Size and Shape of the Earth
Frame of reference determines whether
Earth is “large” or “small”
Earth is “oblate spheroid” rather than a
sphere
– Greeks believed Earth was a sphere 6th century
B.C.
Earth shape affected by
– Bulges in midriff (pliability of lithosphere)
– Topographical irregularities (relatively small)
13. The Geographic Grid (Fig. 1-12)
System of accurate
location is necessary
to pinpoint the position
of any spot on Earth
– Grid system- uses
network of intersecting
lines
– Graticule- grid system
for mapping Earth that
uses parallels and
meridians
14. The Geographic Grid
Fig. 1-13
– 4 Earth features provide reference
points
North Pole
South Pole
Rotation axis
Equatorial plane
– Equator- imaginary midline of Earth
15. The Geographic Grid
Fig. 1-14
– Great Circle- largest circle
that can be drawn on a
sphere, passes through
center
Circle of Illuminationcircle that divides Earth
between light and dark
– Small Circle- plane that cuts
through sphere
16. Latitude
Fig. 1-15
Latitude- distance
measured north and
south of the equator
Length of 1 degree
latitude varies because
of polar flattening
Parallel- an imaginary
line that connects all
points of the same
latitude
19. Longitude
Fig. 1-20
Longitude- distance
measured east and west
Meridian- imaginary line of
longitude extending from
pole to pole
– NOT parallel to each
other
Prime meridian- passes
through Royal Observatory
at Greenwich, England
21. Earth-Sun Relations
Relationship between Earth and Sun vital
because dependent on solar energy
2 Basic Movements:
– Earth’s daily rotation on its axis
– Earth’s annual revolution around the Sun
22. Earth’s Rotation on Its Axis
Earth rotates toward the east (24 hrs)
– Creates illusion celestial bodies rise in the east and set
in the west
Speed of rotation varies from place to place, but
constant at a given place, so humans cannot
sense
Rotational effects:
– Coriolis effect- apparent deflection to right
– Locations experience increased/decreased gravitational
pull of Moon and Sun
– Daily alternation of light and darkness
24. Earth’s Revolution around the Sun
Tropical Year- time Earth makes 1 revolution
around the Sun (approx. 365.25 days)
Earth’s revolution is an ellipse
– Varying Earth-Sun distance does NOT affect seasonal
temperatures
– Perihelion- point Earth is closest to Sun
~147 million km (Jan.3)
– Aphelion- point Earth is farthest from Sun
~152 million km (July 4)
26. The Annual March of the Seasons
Plane of the ecliptic- imaginary plane that
passes through the Sun and through every
point of Earth’s orbit
Inclination- degree Earth’s rotation axis is
tilted (23.5°)
Polarity- Earth’s axis always points toward
Polaris, the North Star
Insolation- Incoming Solar Radiation
31. Changes in Daylight and Darkness
Period of daylight vary throughout year
– Increasing north of the equator from Winter
solstice to Summer solstice (Northern Hem.)
Day length and Sun ray angle determine
insolation amount
– Tropic latitudes are warm because of high sun
angles
– Polar regions cold because of low sun angles
33. Telling Time- Standard Time
Use of local solar time created problems
1884 international conference divided world
into 24 standard time zones, 15 ° long. each
– Universal Time Coordinated (UTC)- formerly
Greenwich Mean Time (GMT); uses local solar
time of Greenwich as standard
36. The International Date Line
Fig. 1-34
International Date
Line- marks where
new days begin and
old days exit
– Time difference of 1
day from one side to
other
– Falls on 180th meridian
37. Daylight-Saving Time
Clocks are set forward 1 hr to extend
daylight into evening
– Originally created in Germany to conserve
electricity
– AZ, HI do not observe
– Was not designed for farmers
After all it makes it darker in the morning
Notes de l'éditeur
Milky Way: 100,000 Light Years in diameter
10,000 Light Years thick
1 Light Year = 9 trillion km
Big Bang theory: 15 billion years ago
Milky Way formed between 4.5 billion and 5 billion years ago
Radius of Earth 4000 mi
Moon is 239,000 miles from Earth
Sun is 150 million km away from Earth (93 million mi)
Nearest star is 40 trillion miles away from earth
High point on Earth 29,000 ft (Everest)
Low point 36000 ft below sea level- Mariana Trench