Places on the earth

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Places on the earth
Latitude and longitude are used to locate your
position on the earths surface. This is similar
to locating something in a street directory.
Great and small circles The earth is a sphere.
If you cut a slice anywhere through the earth,
the slice is in the shape of a circle. Any circle
that has the centre of the earth as its centre is
a great circle. Or any slice that goes through
the centre of a sphere is a great circle. Any
circle whose centre is not the centre of the
earth is a small circle. Or any other slice of a
sphere is a small circle.
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Parallels of latitude
Parallels of latitude are imaginary lines that
run around the earth. The equator is a great
circle that runs around the middle of the
earth. The equator is labelled 0º, and is the
only parallel of latitude that is a great
circle. The other parallels of latitude are small
circles north and south of the equator. A
hemisphere is half a sphere. The equator divides
the earth into the southern and northern
hemispheres. The angle of latitude (?) is the
angle at the centre of the earth (O) between the
equator and the parallel of latitude.
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?
O
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Parallels of latitude
Parallels of latitude range from 90ºN to
90ºS. 90ºN is the North pole. 90ºS is the South
pole. Because these are right at the top or
bottom of the earth, they are dots rather than
circles. This means that as you go south (or
north) from the equator the parallels become
shorter in length. Meridians of
longitude Meridians of longitude are imaginary
lines that run down the earth. They are great
semi-circles that run between the south and north
poles.
They are not parallel as they are close (almost
touching) at the poles and over 100km apart at
the equator. As a result they look like wedges of
an orange.
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Meridians of longitude
The main meridian of longitude is the Greenwich
meridian or prime meridian. The Greenwich
meridian meridian passes through the Royal
Greenwich Observatory in London England. The
Greenwich meridian splits the world into the
eastern and western hemispheres. Meridians of
longitude run around the equator, so they cover a
range of 360º. The angle of longitude (?) is the
angle at the centre of the earth (O) between the
Greenwich Meridian and the meridian of longitude.
The Greenwich meridian is 0º. The meridians of
longitude then go east and west from
there. Opposite the Greenwich meridian is the
international date line. This is at either 180ºE
or 180ºW.
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Positions on the earth
A point on the earth can be located by using its
latitude (the angle north or south of the
equator) and longitude (the angle east or west of
the Greenwich meridian). It is always latitude
then longitude (or alphabetical order). Meridians
of longitude are the long lines going down the
earth. Parallels of latitude are the parallel
lines that change length as you go up or down the
earth. Looking at a map can be deceiving
depending on the projection you use. The most
common projection is the Mecartor projection.
This does tend to distort the areas away from the
equator.
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Example 1
Match the following coordinates to the points
illustrated in the diagram of the earth. a)
(50ºS, 55ºE) b) (30ºN, 55ºE) c) (30ºN, 0º) d)
(75ºN, 55ºE) e) (0º, 0º) f) (0º, 55ºE) g) (50ºS,
0º) h (75ºN, 0º)

• (50ºS, 55ºE) is point
• b) (30ºN, 55ºE) is point
• c) (30ºN, 0º) is point
• d) (75ºN, 55ºE) is point
• e) (0º, 0º) is point
• f) (0º, 55ºE) is point
• g) (50ºS, 0º) is point
• h (75ºN, 0º) is point

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Todays work
Exercise 7-01 Page 250 ? 252 Q1 ? 8, 11 ? 14, 16