Models and dimensions of earth

1. Models of the EarthModels of the Earth

2. Created by L. ZimmermanCreated by L. Zimmerman
Introduction to MapsIntroduction to Maps
Maps are an extremely useful tool for Maps are an extremely useful tool for
many science and non-science many science and non-science
disciplines.disciplines.
They provide “pictures” of They provide “pictures” of
areas/regions/land surfaces!areas/regions/land surfaces!
Correct interpretation can tell you MANY Correct interpretation can tell you MANY
things!things!
–MINGOMINGO!!

3. Created by L. ZimmermanCreated by L. Zimmerman
Location on EarthLocation on Earth
The earth is a sphere, so The earth is a sphere, so
how do we describe where a how do we describe where a
point is on its surface?point is on its surface?
The most common way to The most common way to
locate points on the surface locate points on the surface
is by basic, geographic is by basic, geographic
coordinates: latitude and coordinates: latitude and
longitude. longitude.
These coordinates values These coordinates values
are measured in degrees, are measured in degrees,
and represent angular and represent angular
distances calculated from the distances calculated from the
center of the Earth.center of the Earth.

4. Created by L. ZimmermanCreated by L. Zimmerman
Shape of the EarthShape of the Earth
Earth is most Earth is most
accurately accurately
described as an described as an
oblate spheroidoblate spheroid
(almost a sphere). (almost a sphere).
Flattened at theFlattened at the
polespoles
1.1.Bulges at theBulges at the
equatorequator
N
P
S
P

5. Created by L. ZimmermanCreated by L. Zimmerman
Determining Earth’s ShapeDetermining Earth’s Shape
1.1.Observation of the North Star, Polaris.Observation of the North Star, Polaris.
–Altitude is the Altitude is the heightheight, measured in , measured in degreesdegrees
above the horizon of the observer.above the horizon of the observer.
–The altitude of Polaris changes as an The altitude of Polaris changes as an
observer moves north or south (in the observer moves north or south (in the
Northern hemisphere); this is because Earth Northern hemisphere); this is because Earth
is is sphericalspherical and its surface is and its surface is curvedcurved..

6. Created by L. ZimmermanCreated by L. Zimmerman
LatitudeLatitude
Altitude of Altitude of
PolarisPolaris
00
oo
00
oo
9090
oo
9090
oo
6565
oo
6565
oo
d. Summary: The altitude of Polaris (above the
horizon) is equal to the latitude of the observer on
the globe.

7. Created by L. ZimmermanCreated by L. Zimmerman
Locating the North Star - Locating the North Star - of course you of course you
would need to be in the would need to be in the NorthernNorthern hemisphere! hemisphere!
•The North Star is located at the end of the handle of the Little Dipper.
•The North Star always points in the direction of True North. For this reason
it has been used as and aid to navigation for many centuries.

8. Finding Locations Finding Locations
on the Earthon the Earth

There are three main reference points:There are three main reference points:
EquatorEquator
NorthNorth andand South Geographic PolesSouth Geographic Poles

9. Latitude (parallels)Latitude (parallels)
Describe positions Describe positions NorthNorth and and SouthSouth of the of the
equator. Parallels run equator. Parallels run easteast to to westwest around the around the
world.world.
Parallels are measure in Parallels are measure in degreesdegrees from from 00 to to 9090. .
Those that are above the equator are labeled Those that are above the equator are labeled
NorthNorth; those below are labeled ; those below are labeled SouthSouth..
Each degree of latitude consists of 60 equal Each degree of latitude consists of 60 equal
parts called parts called minutesminutes. .
oEach minute is divided into Each minute is divided into 60 seconds60 seconds
Example: 38Example: 38
oo
53’ 51” 53’ 51”

10. Created by L. ZimmermanCreated by L. Zimmerman

12. Longitude (meridians)Longitude (meridians)
Describes positions Describes positions EastEast and and WestWest of the Prime of the Prime
Meridian. Meridians run Meridian. Meridians run northnorth and and southsouth around the around the
world.world.
The 0The 0
oo
meridian is called the meridian is called the Prime Meridian Prime Meridian and runs and runs
directly through directly through Greenwich, EnglandGreenwich, England..
Locations Locations easteast of Prime Meridian have longitudes of Prime Meridian have longitudes
between between 0 and 1800 and 180
oo
E E. Locations west of the Prime . Locations west of the Prime
Meridian have longitudes between Meridian have longitudes between 0 and 1800 and 180
oo
W W..
Longitude can also be broken down into Longitude can also be broken down into minutesminutes and and
secondsseconds..

13. Created by L. ZimmermanCreated by L. Zimmerman

14. Great Circles & Finding DirectionGreat Circles & Finding Direction
Great circles are used in navigation, generally by Great circles are used in navigation, generally by
pilotspilots. A great circle is any circle that . A great circle is any circle that divides divides
the globe in halvesthe globe in halves..
Geomagnetic Poles Geomagnetic Poles – points on Earth directly – points on Earth directly
above imaginary magnetsabove imaginary magnets
Magnetic declination Magnetic declination – angle between direction – angle between direction
of geographic poles and the compass needleof geographic poles and the compass needle
True North True North – the direction of the geographic North – the direction of the geographic North
PolePole

15. Mapping the Earth’s SurfaceMapping the Earth’s Surface
CartographyCartography – science of map making – science of map making
MapsMaps – flat representations of Earth – flat representations of Earth
The best representation of earth is a The best representation of earth is a globeglobe..
No matter what type of map is made, some No matter what type of map is made, some
portion is always distorted. portion is always distorted. CartographersCartographers
work to minimize the effects of these work to minimize the effects of these
distortions. distortions.

16. Reading a MapReading a Map
LegendLegend - list of symbols and their meanings- list of symbols and their meanings
ScaleScale – indicates the relationship (a ratio) – indicates the relationship (a ratio)
between the distances on the map and the between the distances on the map and the
actual distanceactual distance

17. Created by L. ZimmermanCreated by L. Zimmerman
D. Position Characteristics – D. Position Characteristics – How can the How can the
characteristics of a position be measured and described?characteristics of a position be measured and described?
1)1)Isolines – Isolines – lines lines
on a field map on a field map
that that connect connect
points of points of equalequal
value.value.

18. Created by L. ZimmermanCreated by L. Zimmerman
Examples of isolines:Examples of isolines:
a)a)Contour LinesContour Lines (Topographic) – lines that (Topographic) – lines that
connect points of equal connect points of equal ElevationElevation..
b)b)IsobarsIsobars – lines that connect points of equal – lines that connect points of equal
pressurepressure. Found on a . Found on a weather mapweather map..
c)c)IsothermsIsotherms – lines that connect points of – lines that connect points of
equal equal temperaturetemperature. Found on a . Found on a weather weather
mapmap..
d)d)IsosurfaceIsosurface – A model that represents field – A model that represents field
characteristics in 3-D.characteristics in 3-D.

19. Topographic MapsTopographic Maps
http://www.rollanet.org/~conorw/cwome/hahatonka_topo_map.jpg

20. Features of Topographic MapsFeatures of Topographic Maps
ElevationElevation – height above sea level – height above sea level
Sea level Sea level – point between the highest and lowest tide – point between the highest and lowest tide
levels (elevation at sea level = 0)levels (elevation at sea level = 0)
Contour lines Contour lines – used to show elevation and connect – used to show elevation and connect
all points on the map with equal elevationall points on the map with equal elevation
Contour interval Contour interval – difference in elevation between – difference in elevation between
one contour line and the nextone contour line and the next
ReliefRelief – difference in elevation between the highest – difference in elevation between the highest
and lowest pointsand lowest points
Index contour Index contour – every 5– every 5
thth
line is BOLD and its line is BOLD and its
elevation is labeledelevation is labeled

21. Created by L. ZimmermanCreated by L. Zimmerman
Contour Lines:
Connect all points on
a map that have the
same elevation above
sea level.

22. Topographic MapsTopographic Maps
Colors on topographic maps:Colors on topographic maps:
–Blue: Blue: Water (rivers, lakes, streams, etc.)Water (rivers, lakes, streams, etc.)
–Green: Green: VegetationVegetation
–Red: Red: Contour LinesContour Lines

23. Topographic MapsTopographic Maps
There are many symbols used on the There are many symbols used on the
map. These are explained in the map. These are explained in the
legendlegend..

24. Topographic MapsTopographic Maps
Contour lines spaced close together indicate a Contour lines spaced close together indicate a steep steep
slope.slope.
Contour lines spaced far apart indicate a Contour lines spaced far apart indicate a gentle gentle
slopeslope..
Contour lines that form a closed loop indicate a Contour lines that form a closed loop indicate a hillhill..
Contour lines that form a circle with dashed lines Contour lines that form a circle with dashed lines
indicate a depressionindicate a depression..
V-shaped contour lines indicate a V-shaped contour lines indicate a valleyvalley and the “V” and the “V”
will point will point downstreamdownstream. (Rivers flow DOWNHILL). (Rivers flow DOWNHILL)

25. Topographic MapsTopographic Maps
Depression (shown using hachures)

26. Topographic MapsTopographic Maps
Advanced TechnologyAdvanced Technology: Gives us the : Gives us the
ability to measure and analyze the ability to measure and analyze the
physical properties of Earth with much physical properties of Earth with much
greater precision.greater precision.
–Examples: Examples: GPSGPS and and Weather satellitesWeather satellites..

27. Created by L. ZimmermanCreated by L. Zimmerman
Features of Topographic Maps
Relationship between 3D and 2D representation
3D view
2D view

28. Created by L. ZimmermanCreated by L. Zimmerman
Contour lines
Relationship between topographic features and contour lines

29. Created by L. ZimmermanCreated by L. Zimmerman
Topographic Profile

30. Created by L. ZimmermanCreated by L. Zimmerman
The RESULT – a 3-D pictureThe RESULT – a 3-D picture