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# Lab 17-2 ONLINE LESSON. If viewing this lesson in Powerpoint Use down or up arrows to navigate.

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Lab 17-2 ONLINE LESSON

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LATITUDE AND LONGITUDE

Latitude and longitude is a navigational system that allows for the location of an exact point on the surface of our planet.

Latitude and longitude involves the intersection of perpendicular lines.

A point on our planet is determined by the intersection of latitude and longitude… latitude longitude

Here… latitude longitude

Not there… latitude longitude

Not there… latitude longitude

Here… latitude longitude

Get the drift. latitude longitude

Lines of Latitude are parallel to the equator of our planet…

The equator is the reference line for latitude…it is 0°… The equator divides the northern and southern hemispheres

Southern hemisphere Northern hemisphere

Lines of Longitude are perpendicular to the equator of our planet…they run from the north pole to the south pole.

The Prime Meridian, in Greenwich, England, is the reference line for longitude…it is 0°…

Exactly opposite of the Prime Meridian, on the other side of the planet, is the International Dateline…

The Prime Meridian and International Dateline divide the western and eastern hemispheres.

Western HemisphereEastern Hemisphere

With me so far?

Say yes!

Finding a location on our planet involves the intersection of lines of latitude and longitude.

To find a place, we need to assign numerical values to lines of latitude and longitude…

Lines of latitude are given values from 0° to 90° north or south…degrees (°) are a division of a circle…

Northern hemisphere latitude values are referred to as north or south…example 23° north latitude

xxxx 0° to 90° north 0° to 90° south

Lines of longitude are given values from 0° to 180° west or east…

Western and eastern longitude values are referred to as west or east…example 123° west longitude

0° to 180° west0° to 180° east

In latitude and longitude, it is important which hemisphere is being referenced, north, south, east or west…

As was mentioned, numerical values in terms of degrees have been assigned to latitude and longitude lines…

However, just degrees cannot cover the entire planet…

A system of sub units must be employed in order to accurately locate a position on this planet…

1º1º 1° can be divided into 60 smaller parts called minutes…60

1 1 can be divided into 60 smaller parts called seconds…60

This type of division can provide accuracy to about 30 meters.

º (degrees) (minutes) (seconds)

121º 48 08 W 37º 42 47 N Typical coordinates would look like this…

121º 48 08 W 37º 42 47 N Northern hemisphere

121º 48 08 W 37º 42 47 N Western hemisphere

So now, how do we use these concepts to locate positions on our planet?

We need to use a map. A map is a graphical representation of the surface of the planet. A pocket sized snapshot of part of the earth.

Here is part of a map.

This is a section of the Livermore Quadrangle.

A map illustrates features on the surface of our planet. Such as…

Highways…

Population centers…

Water features…

Terrain and areas of vegetation…

And colleges…

The Livermore Quadrangle will be used for this exercise.

The name is at the top of the map.

It was produced in 1961, and revised in 1980

This information is on the bottom right of the map.

The scale of this map is 1:24,000

This is at the bottom, center of the map.

This means that this map is 24,000 times smaller than the real world…

Every unit on this map, is equal to 24,000 units in the real world…

A distance scale is also provided.

This scale is in miles and kilometers. Oooooooh! Metric.

The Livermore Quadrangle includes latitude and longitude information…

Here is a latitude coordinate… the flashing red line is a line of latitude.

Here is a longitude coordinate… the flashing red line is a line of longitude.

Here is another longitude coordinate… since this is a government map, not all information is fully presented. xx Disregard these numbers

This coordinate means… 121°50 00 west longitude. xx

This coordinate means… 121°47 30 west longitude.

Here is a longitude coordinate… the flashing red line is a line of longitude.

Here is another latitude coordinate… since this is a government map, not all information is fully presented.

This coordinate means… 37°40 00 North latitude.

This coordinate means… 37°42 30 North latitude.

Here is a latitude coordinate… the flashing red line is a line of latitude…

As can be seen, latitude and longitude coordinates are placed around the perimeter of the Livermore Quadrangle.

A bit of map trivia, the eastern and western most boundaries of the map are separated by 7 ½ minutes of arc.

So too are the northern and southern most boundaries of this map. This type of map is referred to as a 7 ½ minute quadrangle.

Notice on the Livermore Quad, black lines that are in concert with lines of latitude and longitude.

These are index lines that will be used to determine latitude and longitude coordinates.

They are associated with the coordinates around the periphery of the map.

For reference purposes, the four cardinal directions are… North South WestEast

Determining the Latitude and Longitude of a point on a map.

An example: locate on the map, the west end of Livermore Municipal Airport

It is located at this position on your map…

These are latitude and longitude scales that are calibrated in minutes and seconds. Scale A is for latitude, while scale B is for longitude.

Notice the division of these scales. The smallest units are in seconds of arc. The entire scale is 2 ½ minutes of arc.

37° 42 30 37° 40 00 To find latitude, place the long scale between the lines of latitude.

Read this value

37° 42 30 37° 40 00 The value is 1 43

37° 42 30 37° 40 00 Add 1 43 37° 40 00 37° 41 43 +

37° 42 30 37° 40 00 So the latitude of the west end of the Livermore Municipal Airport is… 37° 41 43

37° 42 30 To find longitude, place the small scale in between the lines of longitude 121° 50 00 121° 47 30

Read this value

37° 42 30 The value is 1 58 121° 50 00 121° 47 30

37° 42 30 121° 48 83 121° 50 00 121° 47 30 Add 1 58 + 121° 47 30 This is an impossible value because there cannot be more than 60 seconds in each minute.

37° 42 30 121° 48 83 121° 50 00 121° 47 30 Add 1 58 + 121° 47 30 To repair this, subtract 60 seconds from 83 and add 1 minute to 48.

37° 42 30 121° 50 00 121° 47 30 So the longitude of the west end of the Livermore Municipal Airport is… 121° 49 23

So the latitude (la) and longitude (lo) of the west end of the Livermore Municipal Airport is… lo = 121° 49 23 W la = 37° 41 43 N

Your mission from here on out is to determine the la and lo of a whole bunch of places on this planet!!!

Ask Bob for Lab 17-2 questions…

END

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