Chapter 2 Measuring the Earth

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Chapter 2 Measuring the Earth
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1.) MODELS
- A representation of a real object or event
EX map, graph, globe, volcano model
Models are useful because they help study the
object or event easier.
2.) The Shape of The Earth
A. The shape of the Earth is round.
B. How do we know? Evidence
1. Satellite photos. We have actually seen Earth
from above.
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2. A ship sailing away. A ship sinks below the
horizon.
3. People in different places on Earth see
different stars.
EX Northern Hemisphere sees Big Dipper, Little
Dipper
Southern Hemisphere sees Southern Cross
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4. Ferdinand Magellan circumnavigated (sailed all
the way around) the world!
5. Altitude of Polaris (North Star)
Altitude Height, measured in degrees, above the
horizon.
Polaris appears at different altitudes in the sky
depending on where you are on Earth.
Latitude- Distance, measured in degrees North or
South of the Equator.
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Altitude of PolarisLatitude of Observer!!!
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6. Lunar Eclipse- Eclipse of the Moon.
The shape of the Earths shadow is seen on the
moons surface as the moon enters and exits the
eclipse.
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The Earth is NOT perfectly round.
The Earths shape is actually called an oblate
spheroid, which means slightly flattened at the
poles and slightly bulged at the equator.
(Not Enough to see)
B. Diameter/Circumference Measurements of Earth
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C. How do we know the Earth is not perfectly
round?
1. Gravitys pull toward the center of the Earth
changes from the equator to the poles.
The weight of an object at the equator is
less than the weight of an object at the poles.
This is caused by Earths rotation.
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4.) How smooth is the Earth??
Surface features, such as mountains, oceans,
valleys are very minor irregularities on the
planetary scale.
Ex The ocean would be a thin line on the
surface.
This line is way to thick to show the true
ocean depth.
This point is way to big to show the true height
of a mountain
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4. Latitude and Longitude
Latitude- distance, measured in degrees, North or
South of the Equator
Equator- 0
North Pole- 90N
South Pole- 90S
Range 90N to 90S
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Latitude Lines
A. Horizontal- Flat Lat-Flat
B. Parallel to the Equator
C. Start at the Equator
Latitude is found by measuring the altitude of
Polaris in the Northern Hemisphere.
Ex If altitude of Polaris 23, Latitude
of Observer 23N
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Longitude- Distance, measured in degrees, East or
West of the Prime Meridian.
Prime Meridian- Imaginary line that runs through
Greenwich, England from the North Pole to the
South Pole.
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Longitude Lines are
A. Vertical- Long
B. Also known as Meridians
C. Range 180E to 180W
5.) Calculating Longitude
Longitude can be calculated if you know the
clock time at the Prime Meridian (Greenwich Mean
Time)
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Every 15 longitude 1 hour of time on a clock
because the Earth rotates (spins) 15 in 1 hour.
To Calculate Longitude
Longitude(__ E or W time difference ( between
your time (local time) X 15 and time
at prime meridian Greenwich time))
If local time (you) is Earlier than Greenwich
time, your longitude is W .
If local time (you) is Later than Greenwich time,
your longitude is E .
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Ex Your time (local) 400 AM
Greenwich Time 100 AM
Your Longitude 45E
Ex Your time (local) 500PM
Greenwich Time 300PM
Your Longitude 30E
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Ex Your time (local) 10 AM
Greenwich Time 2 PM
Your Longitude 60W
Ex Your longitude 75 W
Your time (local) 3 PM
Greenwich time 8 PM
Everyone on the same longitude has the same
solar time.
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6.) Coordinate System- Intersection of latitude
and longitude lines, making each location unique.
___________ , ___________
Latitude (N or S) Longitude (E or W) Range
(90N to 90S)
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30N 15N 0 15S 30S
30W 15W 0 15E 30E
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EX 1.) What are the coordinates of A? 0, 15 E
2.) What are the coordinates of B? 15S, 30E
3.) What are the coordinates of C? 0, 0
4.) What are the coordinates of D? 22N, 15W
5.) What are the coordinates of E? 15S, 30W
6.) What are the coordinates of F? 30N, 30W
7.) What are the coordinates of G? 35S, 3E
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6.) To pinpoint more specific places
Degrees () are subdivided 1 degree 60 minutes
() 1 minute 60 seconds ()
24N 23N 22N 21N 20N
64E 65E 66E 67E 68E
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8.) What are the coordinates of H? 22N, 67E
9.) What are the coordinates of I? 21N, 68E
10.) What are the coordinates of J? 2330N, 65E
11.) What are the coordinates of K? 2030N, 65
30 E
12.) What are the coordinates of Ithaca, NY? 42
27' N 76 29' W
13.) What are the coordinates of Syracuse, NY?
43 7' N 76 7' W
14.) What are the coordinates of Gloversville,
NY? 43 2' N 74 21' W
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Structure of the Earth
The outer portion of the Earth is classified into
3 major parts
1.) Lithosphere (solid)- Dense, solid shell of
the Earth, composed of rock and soil.

• Thickness- varies from 70-150 km

• Two most common elements- oxygen and silicone

2.) Hydrosphere (liquid)- Consists of the waters
of the Earth Oceans, lakes, rivers and
groundwater.)

• Thickness- varies from 0-4 km

• Two most common elements- Oxygen (O2) and
  Hydrogen (H)

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3.) Atmosphere (gas)- Shell of gasses that
surround the Earth. Air of the Earth.

• Thickness- could reach several hundred km.

• Two most common elements- Oxygen (O2) and
  Nitrogen (N).

The Atmosphere is separated into zones
A.) Troposphere- lowest zone
- most important to life
- made up of mostly Nitrogen (78) and Oxygen
(21)
- Extends up to 12 km above Earths surface.
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• Most weather occurs in this zone

- As height above Earth (altitude) increases in
this zone, air temperature decreases.
- Tropopause- boundary that separates the
troposphere from the stratosphere.
B.) Stratosphere- Clear and dry layer.
- strong, steady winds
-altitude is between 12 and 50 km.
- Jets fly in this zone.
- As altitude increases in this zone, air
temperature increases.
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C.) Mesosphere- altitude is between 50 and 80km.
- as altitude increases in this zone, air
temperature decreases.
D.) Thermosphere- altitude is between 80 and 500
km.
- As altitude increases in this zone, air
temperature increases.
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Field Maps
Regions in space where quantities are measured at
given points, and plotted.
Ex Temp field Pressure field elevation field
A. Reading Field Maps
Isolines- Lines drawn on field maps connecting
points of equal value.

• Isotherm- equal temperature lines.

• Isobar- equal pressure lines.

• Contour- equal elevation lines

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Ex Topographic map with elevation
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On field maps, distance is shown using a scale.
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Determine the distance between the following
points using scale B
1.) 3.5 miles
2.) 5.75 miles
3.) 75 miles
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Drawing Field Maps
Isolines are drawn connecting points of equal
value.
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10.) Topographic Maps Topography- Physical
feature of the Earth. Ex Hills, mountains,
valleys, lakes, rivers
Topographic Maps- A 2-dimensional model showing
elevations of various points on Earths surface.
- They show the shape of the land.
- They also show buildings, roads, trails, lakes,
swamps, etc.
Elevation- height above sea level.
A. Reading Topographic Maps
Contour Lines- Isolines that connect point of
equal elevation above sea level.
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• Contour lines never cross!!!

• Zero (0) contour line sea level

• Index contour line main contour line (darker
  line with number)

Contour Interval Difference between 2 contour
lines.
200
CI 100
100
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Topographic Map Features
Cliff
Hill
Stream
Depression (hole)
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• Valleys make Vs, when crossing a river or
  a road valley.

• Vs always point (bend) upstream.

The stream always flows in the opposite
direction of the way the lines bend.
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Steep
Gentle
C. Gradient (slope) - The change in elevation
between two points.
See pg. 1 of your ESRT
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Gradient change in field value
(elevation) distance
1cm .5 miles
A
B
CI 20ft.
1cm
g 80ft 2miles
g 40 ft/mile
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General rule The closer together the isolines,
the steeper the gradient (slope.)
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D. Topographic map latitude and longitude -
Latitude and longitude on topographic maps are in
the corners of the map.
72 30W
72 15W
43 15N
43 15N
43 00N
43 00N
72 15W
72 30W
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Latitude covered on map above 43 00N to 43
15N (15 min)
Longitude covered on map above 72 15 W to 72
30W (15 min)
F. Topographic map scales
Topographic maps also have a numerical scale to
show distance.
Ex 124,000 This means 1 inch on map 24,
000 in on the ground (2,000ft. Or 1 cm on
map 24, 000cm on the ground.
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G. Topographic Map Profiles
Profile side view of the topography
Ex
Aerial View (top view)
Side View (Profile)
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Example of how to draw an accurate profile from
Point A to Point B
A
B
550 500 450 400 350 300 250 200 150 100 50 0
Distance (miles)