Measuring the Earths Dimensions

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Measuring the Earths Dimensions

• Model of the Earth
• A model is anything that represents
• the properties of an object or system.

1. Physical Mechanical 2.  Mental
3.  Mathematical 4.  Graphic Models
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• II. The shape of the earth
• A. Observations that the earth is curved.
• 1. Ships at Sea
• 2. Eclipses
• 3.  Photographs from space are the best examples
  proving the earth is round.
•  

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• The earth is an oblate spheroid or a NEARLY
  PERFECT CIRCLE
• B. The circumference measured between the poles
  the equator are different.
• 1. Slightly flat at the poles and bulging at
  the equator
• 2. Gravity meters tell us so

• Gravity Stronger at the poles.
• Equatorial Diameter 12,756 km
• Polar Diameter 12,714 km

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• C. Observations of Polaris lead to the conclusion
  that the earth is round.
• Parallelism The north pole points to Polaris.
• The Altitude of Polaris Equals Your Latitude
• Altitude is an angle measured from the horizon.
• Horizon is where the sky touches the earth.
• Zenith straight above your head.

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• Altitude of Polaris is Equal To Your Latitude

• Latitude
• 42 ? North Latitude

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• At the equator your
• altitude to Polaris is 0 ?

• In New York the Average
• Altitude is Between 41 ?
• 45 ? North

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• To find the North Star use the Big Dipper
• The 2 Pointer Stars Point to Polaris

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Finding your way around.
using Polaris
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• III. Locating Positions on the Earth
• A. Coordinate systems are used to locate points
  on a surface.
• 1. On a curved surface, such as earth, we use
  latitude longitude.
• Both reference points are found by using stars
• a.    The equator is the starting point for
  latitude.
• Measured 90 North or South
• Latitude lines are parallel to one
  another
• run like latter rungs.

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• B. The prime meridian is used for the starting
  point of longitude lines.
• Marked in 15 increments as the sun moves across
  the sky.
• Run 180 East or West to the International
  Dateline.
• Each meridian runs the long way meeting at the
  poles.

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• C. Latitude is reported first then Longitude
• 45 North by 30 West

Degrees Minutes Seconds

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• D. There are 24 Time Zones
• The International Date Line _at_ 180? Separates One
  Day from the Next.
• The earth rotates on its axis 15 ? / hour
• Time can be tracked by counting the number of
  hours away from the
• prime meridian.

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• IV. Field Maps
• Field Quantities
• A field is a region of space that has a
• measurable value at every location.

• Scalar Fields magnitude measurements
  (Temperature)
• Vector Fields magnitude and direction (wind
  speed)
• Iso-lines connect points of equal value.
• 4. Iso-surface is a three dimensional surface
  in which every point has an equal value.

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• A. Creating an Isotherm field map
• Connect temperature points of equal value.
• Identify Heat Sources and Sinks

Heat Sink
Heat Source
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• B. Topographic Maps are models showing the
  elevation, shape, and steepness of the land
  surface.
• Contour lines connect points of equal elevation.
• Topographic Maps gives a two dimensional view of
  the land.
• Show Relief or Elevation above sea level.

2000 ft. Contour line
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2. All topographic maps are referred to as
quadrangles or contour maps. A quadrangle is
a 4 cornered map.
Scale showing the ratio of actual distance to
map distance
Compass Direction Magnetic Declination.
Contour Interval
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3. Contour Interval is the change in elevation
from one contour to the next.
Closely Spaced Contours indicate a steep cliff
gradient.
A hill top has closed looped contour lines
Index Contour Lines are thick lines.
V-Shaped contours indicate a stream valley
point uphill
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A profile..
Note the closed contours and u shaped valley.
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4. Topographic Profiles can be drawn using
contour points.
A profile shows the cross sectional view of the
landscape
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• 5. Calculating a gradient or the slope of the
  land.
• ESRT pg 1

• What is the gradient of the hill below the ski
  lift?
• G Change in Field Value
• Distance
• G 1400 ft 450 ft
• 0.8 miles
• G 950 ft
• 0.8 miles
• G 1187.5 ft/mile

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• What is the contour interval?
• What is the highest contour elevation?
• What compass direction is Campbell River from?
• What do closed contour lines indicate?
• What do closely packed contours indicate along
  side a hill?
• Which compass side of Deer Mountain is the
  steepest?
• What is the highest possible elevation for Berry
  Mountain?
• Calculate a gradient for line 1 use your ESRT
  ruler to estimate distances.
• 9. Calculate a gradient for line 2 use your
  ESRT ruler to estimate distances.

Answer the following.
Line 1
Line 2
C.I. 100 Meters