Maps

Or, where on Earth am I?

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?