Download Chapter 1 Introduction to the Earth

Chapter 1
Introduction to the Earth
What is Geography?
• The study of the earth as the home
of humankind.
• Greek - Eratosthenes
• Father of Geography
• Geo means “Earth”
• Graphy means “to write”
• Study how things are different from
place to place
• The study of where things are on the
earth and the reason for the location
• Asks two simple questions - Where
and Why?
• Where are physical featured found ?
• Why are they there?
Why are there
mountains in some
places and not in
other places?
Why are some
places deserts and
some places are
forests?
• Cultural Geography - is the study of where and why
human activities are located where they are.
• Religion, migration, businesses, cities
• Physical Geography - Where and why natural
forces occur.
• Climate, Landforms, vegetation
Science and Geography
• The Scientific Method
• Theory
• Highest order of the understanding for a body of
information
• Testable and repeatable with same results
• Well supported with many independent strands of evidence
• New observations and evidence can change theories
• Geocentric vs. Heliocentric
Earth’s Four Spheres
• Four systems all interacting at various levels
• Three non-living spheres and a fourth living sphere
• Atmosphere
• A thin layer surrounding the
Earth
• Formed by gasses from the
interior of the earth and all
life over time
• Hydrosphere
• All water in the atmosphere,
on the surface and near the
surface
• Liquid, gas and solid
• Lithosphere
• The Earth’s crust and a
portion of the upper
mantle
• Includes 7 continents
and all landforms
• Biosphere
• All organisms, plants,
and animals
• overlaps the other three
spheres
• Seafloor to 5 miles into
the atmosphere
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The size and shape of the Earth
• Pythagoras determined the earth is a
sphere (580-500 BC)
• Eratosthenes (247 BC)
• 26,700 miles circumference
• Actual circumference 24,900 miles
• Sir Isaac Newton
• Bulged at equator, flattened at poles
• Oblate spheroid
• Topographic irregularities
• Mountains, valleys,
• Mt. Everest 29035 feet
• Marianas Trench -36198 feet
The Geographic Grid
• System for accurate locations
• Pinpoint with mathematical precision
• Two sets of lines that intersect at right angles
– Latitude measure North-South of Equator
– Longitude measure East-West of Prime Meridian
Latitude
• Eratosthenes
• Angle of shadow on earth
• Equator
• Divides the Earth into a Northern
and Southern hemispheres
• Angle north or south of the
Equator
• Latitude increases as one travels
north or south of the Equator
• 0 degrees at Equator
• 90 degrees at Poles
Parallels of Latitude
• Parallels are always parallel
to one another
• Parallels are equally spaced
between the equator and the
poles
• 1 degree of latitude = 69 miles
• Parallels of Latitude are true
east/west lines
• Political Boundaries
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• Significant parallels of latitude
• Equator 0o
• Tropic of Cancer 23.5o N
• Tropic of Capricorn 23.5o S
• Arctic Circle 66.5o N
• Antarctic Circle 66.5o S
• North Pole 90o N
• South Pole 90o S
• Bands of Latitude
–
–
–
–
–
Low latitude - Equator to 30o N/S
Midlatitudes - 30o to 60o N/S
High latitude - greater than 60o N/S
Equatorial - within a few degrees of the equator
Tropical - within the tropics (23.5o N to 23.5o S)
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Longitude
• Description of east-west location
• Much harder to determine and
measure
• No natural division
• Earth spins on it’s axis
• Age of Discovery
–
–
–
–
–
1707 British naval disaster
Star charts
John Harrison - Clockmaker
13 Prime meridians
1884 conference
• A meridian is a line connecting
all points along the same
longitude
• Measured East and west of the
Prime Meridian (Greenwich)
• Meridians are spaced farthest
apart at the equator and
converge to a single point at
the poles
• Divides the Earth into Eastern
and Western Hemispheres
• 180 degrees East and West
• International Date Line
Measuring Latitude and Longitude
• Measurement based on a circle
• 360 degrees in a circle
• 60 minutes in one degree
• 60 seconds in a minute
• Gives each location on Earth a
unique identifier
• Can provide very accurate
measurement
• Degrees, Minutes and Seconds
• 35o 55’ 45” N
• 118o 18’ 19” W
Earth’s Place in the Universe
• The Universe contains at least 125 billion galaxies
• Our galaxy, The Milky Way contains 300 billion stars
• The center of our galaxy contains a super massive
black hole
• 50 billion planets in The Milky Way, 500 million in habitable
zone
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The Solar
System, Sun
and Earth
1 Sun
8 Planets
176 moons
Thousands of
comets
• 4.6 billion years
• Contains all life that we know
•
•
•
•
Earth-Sun Relations
• Plane of the Ecliptic
• Earths orbit is not perfectly circular
• Closest 91.5 million miles
• Furthest 94.5 million miles
• The earth revolves around the sun.
• 365 days 5 hours,
42 minutes, 46 seconds
• Leap years
The Reason for the Seasons
• Five factors are responsible for the seasons
•
•
•
•
•
Earth’s revolution around the sun (365 days)
The rotation of the earth (24 hours)
The tilt of the Earth (23.5 degrees)
Tilt of the Earth remains fixed
Appears as a spheroid to the sun
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The Annual March of Seasons
• Caused by the angle at which the suns rays strike
the surface of the earth
• June Solstice - June 21
– Sun perpendicular to Tropic of Cancer
– 24 hours of sun at Arctic Circle
– 24 hours of darkness at Antarctic Circle
• September/March Equinox
– Sun perpendicular to Equator
– All locations on Earth has 12
hours of light
• December Solstice - December 21
– Sun perpendicular to Tropic of
Capricorn
– 24 hours of sun at Antarctic
Circle
– 24 hours of darkness at Arctic
Circle
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