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Unit 1 Measuring the Earth
In this unit you will learn about the
size, shape and features of the earth.
You will also learn how to read maps,
from the simple to the complex.
A. Models –
things that help explain events
1. ___________uses observations of sight to provide
Physical
us with explanations
example: globe
Laboratory models used to simulate
2. ____________natural events
example: Stream table
3. _____________images of something in
Mental
your mind that you are trying to understand
A. Models –
things that help explain events
4. _____________formulas and equations that
Mathematical
explain certain properties of a
material
or system
5. ______________uses graphs to simplify
Graphic
certain relationships
B. Spherical Earth –
evidence to prove it.
1. The Mast of a ship was the first part to appear
over the horizon and the last part to disappear.
2. Change in the altitude of the North Star (Polaris) and
other celestial objects when you travel north or south.
The altitude of Polaris equals the latitude!
Polaris
• Only star in the night sky that does not move,
because Earth’s axis points directly at it
• Also called the “north star” or the “pole star”
• Very last star in the handle of the Little
Dipper
• Can only be seen in the Northern Hemisphere
• Altitude = Latitude of Observer
• Can be found using the Big Dipper
B. Spherical Earth –
evidence to prove it.
3. Shadow of Earth during a lunar eclipse is always the
arc (part) of a circle.
4. Not a perfect sphere,(
) an
Oblate Spheroid
object at the equator will weigh slightly less
than
an object at one of the poles because the Earth has a
slight bulge at the equator.
5. Space photos.
Views from space
Earth Shape PowerPoint
C. Earth’s Dimensions
Circumference at Equator 40,076 km
Circumference at Poles 40,008 km
Diameter at Equator
12,756 km
Diameter at Poles
12,714 km
Land 29 % of surface
Water 71 % of surface
FYI – Moving at 55 mph it would take you
one month to circle the earth.
E. Earth Structure
1. Lithosphere- Crust and top of mantle,
solid and rocky
Hydrosphere
2. _______________-thin
layer of water resting on the
lithosphere.
-covers about 70% of the Earth’s surface.
Atmosphere
3.________________-a
relatively thin shell of gases,
held to Earth by gravity.
78% Nitrogen, 21% Oxygen, 1% mostly Argon,
Carbon Dioxide, Helium and Water Vapor
E. Earth Structure
Liquid layer
Made up of solid
Nickel and Iron
Weather takes
place here
F. Coordinate System - Latitude
System of imaginary lines that help determine the
location of a point on the Earth’s surface.
1.Latitude -distance in
degrees__________________________________.
north or south of the equator
-latitude numbers are followed by an N if they’re
north of the equator and an S if they’re south of
the equator.
-equator
0°
-North Pole 90°N
-South pole 90°S
43.3091°N or 43°18’45”N
-Attica
F. Coordinate System - Latitude
_______________-lines
that measure latitude.
Parallels
-they are parallel to the equator (horizontal).
-degrees of latitude are about 111.1 kilometers
from each other. Same for all lines of latitude.
_____________-(North
Star)- The angle of altitude of
Polaris
Polaris in a given location in the northern
hemisphere is equal to the latitude of that
location.
Very important don’t forget!
F. Coordinate System - Longitude
2. Longitude
-distance in degrees east or west of Prime Meridian
-longitude numbers are followed by an E if
they’re east of the Prime Meridian and a W if
they’re west of the prime meridian.
-Prime Meridian- line that passes through
Greenwich, England and connects the
North and South Poles.
-
0
degrees longitude.
F. Coordinate System - Longitude
-____________-imaginary
Meridians
semicircles that connect the
poles and measure longitude
-the distance between them is greatest at the equator
and they come together at the poles
-180 meridian-line on the opposite side of the Earth as
the Prime Meridian.
-in the middle of the Pacific Ocean
-______________________-roughly
follows the 180
International Date Line
meridian but does go around some land areas.
-where the date changes.
F. Coordinate System –
Longitude and Time
chronometer-very accurate clock that keeps time at the
Prime Meridian (Greenwich Mean Time- G.M.T.) and the
solar time (time by the sun) at any other meridian.
questions:
1. How many are there degrees in a circle? 360°
2. How many hours are there in a day?
24 hours
3. How many degrees would the Earth rotate in one hour?
360°
15°/hr.
24 hours =
F. Coordinate System –
Longitude and Time
facts:
1.In the Western Hemisphere, local time is earlier
than Greenwich time.
2.In the Eastern Hemisphere, local time is later
than Greenwich time.
questions:
1.If it is 12:00 noon where you live and the chronometer
reads 5:00 PM Greenwich Time:
a. How many hours are the times apart? 5 hours
b. What is your degree longitude? 5 hrs. X 15°/hr. = 75°
c. Are you in the Eastern or Western Hemisphere? Western
G. Fields and Field maps
___________Isolines
lines connecting points of equal value on
a map.
__________Isobars lines that join points of equal barometric
pressure on a weather map.
Isotherms lines of equal temperature.
__________Contour Lines
_________
__-lines joining points of equal elevation.
G. Fields – Contour Maps
contour map- (topographic map)
- Two dimensional model which shows the
elevation of various points on the Earth’s surface.
Contour lines isolines that connect points of equal
_____________elevation above sea level.
Contour Interval
_________________difference in value between two
contour lines.
What is the contour interval of this map?
20 feet
G. Fields – Contour Maps - Depressions
depressions- pits holes or low areas in the Earth.
- shown on contour maps as a hachured line.
- first hachure has the ____________value
as the
same
lowest
_____________contour
line near it.
-any hachured lines inside the first decrease
in elevation by the contour interval
.
Both lines
are 100 feet
Elevation of this
line is 80 feet
G. Fields – Contour Maps - Direction
Direction- most maps have an arrow to indicate north, if
not they are usually oriented with north at the top.
-latitude and longitude are usually on maps as
well.
-degrees are divided into 60 minutes and minutes
are divided into 60 seconds.
What is the latitude and longitude of the center of Jones
Swamp?
41° 43’ 15” N
72° 17’ 45” W
G. Fields – Contour Maps – Map Scale
Map scale
ratios-many maps have ratios printed on them.
-An example is 1:10,000 which means every one
inch on the map equals 10,000 real inches.
This works for any unit. One centimeter equals
10,000 cm.
scale-distance scale
-line that shows what length the distances on
maps are equal to. Called a graphic scale.
question- What is the distance from the period in Bert
Mtn. to the apostrophe in Bob’s Creek? 3.5 miles
G. Fields – Contour Maps - Profiles
Profile Procedure
1. Place a piece of paper
along the area where you are
drawing the profile.
2. Place a mark where each
line touches the paper and
label it with the elevation.
3. Take the strip of paper and
place it on the bottom of the
graph.
4. Plot the elevations on the
graph and connect the points
with a line.
G. Fields – Contour Maps - Slope
map slope- (gradient)
-determined by comparing the rate of change in
elevation between two points
gradient =
Change in field value
Distance
questions
1. What is the elevation of the period in Bert Mtn.? 200 ft.
2. What is the elevation of the apostrophe in Bob’s Creek? 120 ft.
3. What is the distance between them? 3.5 miles
G. Fields – Contour Maps - Slope
4. What is the gradient?
gradient =
200 ft. – 120 ft.
3.5 miles
80 ft.
3.5 miles
Gradient = 22.9 ft/mile
5. If the contour lines are close together , what is it like
there?
Steep
6. If the Contour lines are far apart, what is it like there?
Gentle or gradual
G. Fields – Contour Maps – Stream Flow
- streams always flow downhill
- contour lines always bend upstream when they cross
a stream.
questions1. Which direction is Bob’s creek flowing? West
2. Which direction is Denbrook flowing? South