Chapter 2 Flashcards
1
Q
what is weird about the mercator projection
A
it distorts the size of the countries
2
Q
on the mercator map what is bigger Greenland or Canada, and is that accurate?
A
Mercator shows Greenland is bigger but in reality Canada is much bigger
3
Q
what is Geodesy
A
the study of the earth’s shape, orientation in space and gravity
4
Q
what is the general shape of the earth
A
an ellipsoid
5
Q
is the earth a perfect sphere
A
NO
6
Q
where does the earth bulge
A
at the equator
7
Q
what is a geoid
A
a model of earth using sea level as a base
8
Q
what causes variations in strength of gravity’s pull
A
variations in size, shape and mass of earth
9
Q
what region on earth has stronger gravitational pull
A
mountains (regions with more mass)
10
Q
what region on earth has weaker gravitational pull
A
areas with less mass (valleys)
11
Q
what is the geoid of earth based on
A
the idea that water covers the entire surface of earth and it is not affected by moon, wind or waves
12
Q
what does a geoid measure
A
global mean sea level that is used to measure precise surface elevations
13
Q
what force ONLY affects a geoid
A
gravity
14
Q
what does a geoid define
A
zero elevation (elevation around earth is generally the same)
15
Q
describe where the geoid of earth rises and falls
A
rising where gravity is high
sinking where gravity is low
16
Q
what is a datum
A
a reference surface/model of earth
17
Q
what is a datum used for
A
plotting locations
18
Q
what shape is a datum
A
ellipsoid
19
Q
where is a datum in respect to the geoid
A
above in some spots and below in others
20
Q
describe two types of datums
A
local datums approximate the Earth’s shape in a specific area
global datums approximate the Earth’s shape globally
21
Q
what are two examples of datums
A
World Geodetic System 1984 (WDS84)
North American Datum 1983 (NAD83)
22
Q
is WGS84 a global or local datum
A
global (designed to model the whole earth)
23
Q
is NAD83 a global or local datum
A
local - designed to model NA only
24
Q
what is datum transformation
A
a series of calculations that change one datum to another
25
where on the earth is there flattening
at the poles
26
where on earth is there bulging
at the equator
27
what does the geoid model use to determine mean sea level
differential forces in gravity
28
what are used to establish geographic coordinate systems (GCS)
datums
29
what are geographic coordinate systems (GCS)
global reference system for determining a location on a 3D ellipsoid
30
what type of units are used in GCS
angular units
31
what are used for finding location with GCS
lines of longitude and latitude
32
what is longitude
imaginary lines on the globe that run from pole to pole
33
what is the origin (0 degrees) for longitude
prime meridian
34
what are longitude measurements east of the prime meridian
positive
35
what are longitude measurements west of the prime meridian
negative
36
what direction do longitudinal values increase
moving east and west
37
what is the max degrees for longitude
180 east and west
38
where do lines of longitude meet
center of the pacific ocean (180 degrees)
39
is this longitude or latitude
longitude
40
what is latitude
imaginary lines on the globe running east to west
41
where is the origin for latitude
the equator
42
what are latitude measurements north of the equator
positive
43
what are latitude measurements south of the equator
negative
44
is this longitude or latitude
latitude
45
what is the max degrees for latitude
90 north and south
46
what is the north quadrant of the globe
all positive latitudes north of equator
47
what is the South quadrant of the globe
all negative latitudes south of equator
48
what is the east quadrant of the globe
all positive longitudes EAST of prime meridian
49
what is the west quadrant of the globe
all negative longitudes west of prime meridian
50
how many minutes are in a degree
60
51
how many seconds are in a degree
3600
52
what fraction of a circle is 1 degree
1/360 of a circle
53
1 minutes is how many degrees
1/60 of a degree
54
what are the axes when plotting longitude and latitude on a cartesian plane
x axis - longitude
y axis - latitude
55
what does DD stand for
decimal degree
56
what is DD
the fractional decimal equivalent to DMS
57
what is DMS
degrees minutes second
58
what does a negative sign mean in DMS
locations that are south or west
59
how to convert DMS to DD
DD = D + (M/60) + (S/3600)
60
what is a problem when rounding decimals in coordinate systems
can drastically change where you end up in the world
61
why is measuring distance in GCS a problem
because lines of latitude are equally spaced across the world but longitude is NOT
62
what is key to all geographical applications
spatial location
63
what are map projections
conversion of location from a 3D earth to a 2D surface
64
what is the issue with projections
the distortion that results (distortion of size, shape, distance or direction)
65
what must you project onto when doing projections
a developable surface
66
what is a developable surface in projections
a piece of paper wrapped around the globe
67
three main types of developable surfaces
1. azimuthal
2. conical
3. cylindrical
68
contrast the three types of developable surfaces
1. azimuthal
the surface touches the globe in ONE spot
2. conical
the surface covers the globe in a cone like shape
3. cylindrical
the surface wraps around the earth like a cylinder
69
type of developmental surface
conical
70
type of developmental surface
cylindrical
71
type of developmental surface
azimuthal
72
what are three ways of orientating the developmental surface
1. normal
- wraps around the equator
2. transverse
- wraps around longitude
3. oblique
- wraps around on an angle
73
conical vs secant projection types
conical
- touches the globe at a single point
secant
- cone projection touching it along two latitude lines
74
what is the lambert conformal conic project
a conical secant projection that minimizes distortion and maintains local angles and shapes
75
type of projection
lambert conformal conic project
76
what type of projection isthe mercator projection
a cylindrical projection
77
what does the mercator projection distort
size of countries
(poles are larger and equator is smaller)
78
what was the mercator projection used for
navigation by compass
79
type of projection
mercator projection
80
what does the peter's projection distort
elongates size of continents at the equator and compresses them at the poles
81
type of projection
peter's projection
82
what are some potential reasons maps have north at the top
1. sailors used compasses and north star to navigate
2. mercators map orients north in 1569 and sets the trend
3. north is up based on Europeans doing most of exploring
83
is most of world's pop in north or south hemisphere
north
84
is Africa in north or south hemisphere
most is in the north
85
what makes up the majority of southern hemisphere
water
86
how much of earth's land is in the southern hemisphere
33%
87
are there maps that are right
NO - all are wrong in some way
88
are projected maps correct
NO - impossible to accurately transcribe 3D object on 2D surface
89
what is the projected coordinate system
coordinates on a flat 2D surface
90
what are constant in the projected coordinate system
1. lengths
2. angles
3. areas
91
what is the projected coordinate system based on
geographic coordinate system (GCS)
92
what is the most common type of projected coordinate system
universal transverse mercator (UTM)
93
what does the UTM do
divides earth into 60 zones that are EACH 6 degrees in longitude
94
what latitudes does the UTM NOT exceed
84 degrees NORTH
80 degrees SOUTH
95
where does the UTM start counting and in what direction
counts east from the 180th meridian
96
how are zones in the UTM split
north and south of the equator
97
what zone is alberta in
zone 11 and 12
98
what does each zone in the UTM have
x and y coordinates measured in meters
99
describe what the x and y coordinates mean in a UTM zone
the x coordinate counts east or west of the central meridian
the y coordinate counts north or south from the equator
100
what is easting and northing in UTM zones
northing refers to the y coordinate of a zone
easting refers to a x coordinate of a zone
101
in the UTM where does northing count in the northern hemisphere
from the equator (and up)
102
what does the equator have a value of in the North hemisphere
0
103
what does the equator have a value of in the southern hemisphere
10 million
104
how is a location found in the southern hemisphere using UTM
subtracting the distance from the false northing
105
what does a false northing refer to
in the UTM a false origin of 10,000,000 meters south of the equator is used to avoid negative northings
106
what is easting in the UTM
distance east or west of the central meridian
107
what is false easting in UTM
108
contrast false easting from northing
false northing
- a false origin of 10,000,000 meters SOUTH of the equator is used to avoid negative northings
false easting
- The central meridian is assigned a false easting of 500,000 meters
109
what coordinate (x or y) does false easting affect
x coordinate
110
what coordinate (x or y) does false northing affect
y coordinate
111
why does the UTM have false easting and northing
to ensure x and y values are always positive
112
are locations EAST of the central meridian added or subtracted
added
113
are locations WEST of the central meridian added or subtracted
subtracted
114
why do UTM locations need a zone number attached to the coordinates
because easting and northing values repeat in each of the 60 zones
115
pros of UTM
1. minimal distortion
2. uniform grid system (used all over world)
3. global coverage
116
cons of UTM
1. cannot be used in polar regions
2. limited width zones (each zone stuck in the 6 degrees longitude)
117
what are two special UTMs built for AB
1. 10 TM
expands the 6 degree width of each zone to 10 degrees
2. 3TM
decreases the 6 degree zones to 3 degrees
118
what was western canada divided into
7 one square mile sections
119
what were the 7 sections of Western Canada defined by
meridians
120
what are the 7 meridian systems going from East to West in Canada
1. west of Winnipeg
2. Manitoba/sask border
3. moose jaw sask
4. sask/AB border
5. Calgary
6. grand prairie
121
what is the base unit for the dominion land survey
township
122
what is a township
6 mile x 6 mile area of land
123
how many tires of townships are there in the dominion land survey
two tiers to the north AND two tiers to the south
124
where in a township is it smaller? larger?
north - smaller
south - larger
125
how are townships designated
township number and range number
126
what is township 1
the FIRST north of the First baseline (canada/US border)
127
how do township numbers increase from township 1
northward
128
what happens when range numbers meet at each meridian
they restart counting from range 1 INCREASING to the WEST
129
describe how townships are further broken down
one township has 36 sections (1 x 1 mile)
EACH of the sections (1 x1 mile) has 4 quadrants
each of the 4 quarter sections are sectioned into 16 legal subdivisions
130
