Or, where on
Earth am I?
Maps
Latitude and Longitude
Position on Earth is determined in several
different ways, using different systems.
• Latitude and longitude is one way.
• UTM coordinates is another, which we will not
deal with here, but is widely used for
orienteering, handheld GPS systems, in
military operations, and for various mapping
applications.
0 degrees Longitude runs through
Greenwich, England (Why?). 0
degrees latitude is the equator.
The lines of latitude are measured from Earth’s
center, from 0 to 90 degrees. 90○ North is the North
pole. What is 90 ○ South?
Lines of longitude run between the poles. Here is
shown 0-60 degrees East and 0-80 degrees West of
the Prime Meridian, or 0 degrees longitude. You can
also just go from 0 to 360 degrees instead.
So, where is the US, and Seattle?
What is the approximate latitude and longitude of Seattle?
What would our longitude of Seattle be if were exactly ½ way around the world from Greenwich
England (the Prime Meridian)?
Additional units for latitude and
longitude
• Each degree is broken down into minutes.
– 1 degree of latitude or longitude = 60 minutes.
• Each minute is broken down into seconds.
– 1 minute of latitude or longitude = 60 seconds.
Degrees, minutes and seconds of
latitude:
• “A degree of latitude is approximately 69
miles, and a minute of latitude is
approximately 1.15 miles. A second of latitude
is approximately 0.02 miles, or just over 100
feet.”
Degrees, minutes and seconds of
Longitude:
• “A degree of longitude varies in size. At the
equator, it is approximately 69 miles, the same
size as a degree of latitude. The size gradually
decreases to zero as the meridians converge
at the poles. At a latitude of 45 degrees, a
degree of longitude is approximately 49 miles.
Because a degree of longitude varies in size,
minutes and seconds of longitude also vary,
decreasing in size towards the poles.”
To read more about latitude and
longitude, this is an excellent resource:
• http://nationalatlas.gov/articles/mapping/a_l
atlong.html
• On topographic maps, and various electronic
mapping software, you can determine a
location using latitude and longitude. On the
maps you use today, you will be using the
latitude and longitude given on the edges of
the map to determine your approximate
location.
Distortion
• When representing the world in 2-D,
distortion is going to occur
Distortion
• When representing the world in 2-D,
distortion is going to occur
Polar Maps:
Topographic Maps
• Contour Lines: Lines of equal elevation
Topographic Map Rules:
• Contour lines connect points of equal elevation
• Contour lines do not cross (except in rare case of overhanging
cliff)
• Contour lines never split (diverge)
• Contour lines do not end except at the edges of the map or by
closing on themselves
• Spacing of lines is related to steepness of slope: Widely
spaced means low slope, closely spaced means steep slope
• Rounded hill is represented by a concentric series of closed
contours
• Contour lines vorm V’s which point upstream.
Meteor Crater
Mt. St. Helens Before
Mt. St. Helens After
Mt. St. Helens After
Ocean Floor maps
• Your map is only as good as your
detection techniques.
• Most ocean floor maps were
created in the post-WWII era:
http://oceanexplorer.noaa.gov/history
/history_oe.html
Ocean Floor maps
• Your map is only as good as your
detection techniques.
• Most ocean floor maps were
created in the post-WWII era:
http://oceanexplorer.noaa.gov/history
/history_oe.html
Mars
We have mapped the surface of Mars with more detail
than we have mapped the surface of our ocean floor.
Why?