Latitude and Longitude is a complicated form of a very simple
concept - grid lines that divide a map into smaller square
sections. Most students have used gridlines for years, with games
like Battleship.
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There are two main types of gridlines commonly used in maps:
Letter-Number ex. A2 Number-Number (which can be divided into two)
Four-figure ex. 0225 Six-figureex. 023257
Slide 4
Here you can see a very simple letter-number grid. What is
located at: C2? B5? D2? Where is the: Red oval? Green triangle?
Purple square?
Slide 5
Number-Number Grids are a little harder to work with, but allow
for the possibility of more detail. Four-figure and Six- figure are
the most common grid types.
Slide 6
The Numbers crawling along the bottom are the Eastings. Read
them first. The numbers climbing up the side are the Northings.
Read them second. Remember: Babies crawl before they climb!
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Four-figure Grid References lack detail. Divide the spaces into
ten equal parts to enable the use of six-figure grid references,
which are more accurate.
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The earth is divided up with imaginary lines that help us
measure distances. These lines are known as lines of latitude and
lines of longitude.
Slide 10
Lines of latitude run around the globe. They are parallel to
each other. The longest latitude line is the Equator (0). Lines get
shorter and shorter as they get closer to the poles.
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The Earth is divided into 181 parallel lines from the North
Pole to the South Pole. There are 90 lines north of the Equator and
90 south of the Equator.
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Major Lines of Latitude
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There are 7 major lines of Latitude (as shown in Figure
A).
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The imaginary line of latitude that runs around the middle of
the earth is known as the Equator. 0 latitude is called the Equator
because it divides the earth into two equal halves: the Northern
and Southern Hemispheres.
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The 90 th parallels are called the North Pole (90N) and South
Pole (90S). They mark the earths axis (the line around which the
earth rotates)
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The Tropics: Tropic of Cancer 23.5N Tropic of Capricorn 23.5S
These imaginary lines mark the area of the earth that can have the
sun directly overhead. Between these lines is the hottest part of
the world (the tropics).
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The Circles: The Arctic Circle 66.5N The Antarctic Circle 66.5S
These imaginary lines mark the zones of twenty-four hour darkness
or light.
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In winter, the areas between these lines and the corresponding
pole will be dark for several months. In summer, these areas will
experience twenty-four hour daylight for several months.
Slide 19
On the globe there are imaginary lines that run from the North
Pole to the South Pole. These lines are called meridians or
longitude lines.
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Another way to see lines of longitude (showing their degrees as
the 360 of a circle):
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There are 360 meridians. Meridians are numbered from the 0
going East to 180 and going West to 180. These numbers represent
the distance from the Prime Meridian.
Slide 22
Figure B shows the two most important meridians and how
meridians are drawn on a map with a view from above the North
Pole.
Slide 23
The most important line of longitude is the Prime Meridian (0).
This line runs through Greenwich, England (so it is also called the
Greenwich Meridian). All other lines are measured either East or
West of this line.
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Washington, D.C. (77 3' 2.3 W Rio de Janeiro (43 10' 19 W)[2]
Madrid (3 41' 16.58 W) Paris (2 20' 14.025 E) Rome (12 27' 08.4 E)
Alexandria (29 53' E) Saint Petersburg (30 19' 42.09 E) Jerusalem
(35 13' 47.1 E) Ujjain (75 47' E) Kyoto (135 74' E) Mecca (39 49 34
E)
Slide 25
Directly across from the Prime Meridian is the International
Date Line, which approximately follows the 180 Meridian. This line
moves a little bit in order to go around land masses and
islands.
Slide 26
At this line, the date changes one entire day. For instance, if
it is Monday in China, it is Sunday in Canada. If it is Tuesday in
Tonga, it is Monday in Samoa at exactly the same time!
Slide 27
The longitude and latitude of a place are called its
coordinates. Longitude and latitude are first measured in degrees.
Each degree can then be divided into sixty parts called minutes for
more accuracy. Likewise, each minute can be divided into sixty
parts called seconds in order to be very accurate.
Slide 28
Degrees are usually shown with a . Minutes are usually shown
with a . Seconds are shown with a . Sometimes, the symbols for
degree, minute, and second are not actually given. Seconds are very
accurate and would be used to show detail. Empire State Building,
New York, NY LATITUDELONGITUDE 40 44 54 N 73 59 08 W
Slide 29
For example, New York could be shown with degrees and minutes.
Seconds would be used to show the location of places in New York,
such as the Empire State Building. Empire State Building, New York,
NY LATITUDELONGITUDE 40 44 54 N 73 59 08 W
Slide 30
In an atlas, the coordinates are usually given with both
degrees and minutes. Often the minutes are not actually needed and
actually make it harder to find a location on a map. In these
situations, it is important to know how to round off.
Slide 31
Slide 32
When thinking of rounding off, it is important to remember that
there are 60 minutes in one degree. So, half of that is 30 minutes.
Anything below 30 minutes will round down. Anything 30 minutes or
higher will round up. 30 minutes or higher? ROUND UP 29 minutes or
lower? ROUND DOWN
Slide 33
Slide 34
Round off the following sets of coordinates. 1. 1432 N2228 W 2.
8050 S3015 E 3. 2530 N2930 E 4. 8950 N17905 W
Slide 35
Round off the following sets of coordinates. 1. 1432 N2228 W 2.
8050 S3015 E 3. 2530 N2930 E 4. 8950 N17905 W
Slide 36
There are two basic skills you need to master in order to use
latitude and longitude: 1. Find a place when you are given the
coordinates. 2. Find the coordinates when you are given the name of
a place.
Slide 37
Step 1 Round off to the nearest degree if necessary. Step 2
Find the nearest major latitude & longitude lines (usually
every 10). Step 3 Find the intersection of those lines. Step 4 Move
from that intersection to where you estimate the coordinates
are.
Slide 38
M.4N 8E N.7S 32E O.1435N 2828E P.842S 313E Q.2746N 3620E M. N.
O. P. Q.
Slide 39
Step 1 Find the location on the map. Step 2 Move from that
location to the nearest intersection of major lines (usually every
10). Step 3 Find out the coordinates of that major intersection
Step 4 Estimate the coordinates to the nearest degree. Step 5
Estimate the minutes, if necessary. Step 6 Check your answers in
the gazetteer if it is available.
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Slide 42
The earth is divided into 25 different time zones.
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They are separated by one hour intervals.
Slide 44
There is a new time zone roughly every 15 degrees of
longitude.
Slide 45
The zones are measured in hours behind or ahead of Greenwich
Mean Time (GMT), which is the time at the Prime Meridian Line.
Slide 46
Governments can change their countrys time zone. So for
convenience the whole country can be on the same time.
