- 2 Latitude and longitude, seasons
Northern hemisphere
Look at a globe that represents the Earth. Notice that it is divided into a
grid pattern by lines drawn across, from east to west (lines of latitude) and up
and down, from north to south (lines of longitude). These lines can be used to
define the geographical location of any place on Earth.
Equator
Southern hemisphere
What we should know about lines of latitude
A 2.1 Lines of longitude and latitude
and location of continents
Northern hemisphere
Equator
Tati
Southern hemisphere
A line of latitude is like a slice cut across the Earth. Latitudes are circles and
are parallel to each other.
The biggest circle is the latitude around the middle of the Earth and
is called the equator. The equator divides the Earth into two halves or
hemispheres: the northern hemisphere and the southern hemisphere.
The equator is a circle with its centre at the centre of the Earth, so it is
called a great circle (see figure 2.9). Latitude is measured as the angle
between a line from a point on a circle of latitude to the centre of the Earth, and a
line from a point on the equator to the centre of the Earth, both on the same line of
longitude (see figure 2.3) and may be stated as north (N) or south (S). The
latitude at the equator is 0°, at the North Pole it is 90°N and at the South
Pole it is 90°S. Lines or parallels of latitude intersect lines or
meridians of longitude at right angles. 7 A change of one degree
of latitude corresponds to a
distance of 111 km along a line of longitude. Some significant
lines of latitude are:
0° – the equator 23° N - the Tropic of Cancer 66° N - the
Arctic Circle 23°S - the Tropic of Capricorn 6620S - the
Antarctic Circle
A 2.2 The hemispheres
North Pole
90°
60°N
66°N Arctic Circle 66°N
- 60°N
30°N 23' NA
Tropic of Cancer
23 N
Equator 234
30' N
2
Tropic of Capricorn
2 345
30 S
30 SV
60%6 Antarctic Circle 64.69S
90°
South Pole A 2.3 Lines of latitude
What we should know about
lines of longitude (meridians)
North
Pole
90
°
Longitude
Laritude
40°
S
60°
S
Meridians of longitude run from north to
south and pass through the poles. The imaginary
line joining the north and south poles is the axis of
the Earth, about which it spins. All lines of
longitude bisect the Earth. All lines of longitude are
great circles. The line of longitude at Greenwich, in
London, is the prime meridian and is described as
09. All other meridians are numbered east or west of
it. Longitudes are labelled according to the size of
the angle measured at the equator between a line from the
meridian to the centre of the Earth, and a line from the prime
meridian to the centre of the Earth. These angles: are
measured east or west of the prime meridian. Lines of
longitude are widely spaced at the equator. but meet at the
poles. Meridians intersect with all parallels of
latitude. A change of one degree of longitude at the
equator corresponds to a distance of 111 km. It
takes the Earth 1 hour to turn through 15° of
longitude or 4 minutes to turn through 1°.
80'S
09
90°
South
Pole
A 2.4 Lines of latitude and
longitude
Global time zones
(Activity
Longitude and time Longitude is
important in determining local time.
Not all places see the Sun at the same time,
because of the shape of the Earth and its rotation,
so local time differs from place to place according
to longitude. Time all over the world is based on
Greenwich Mean Time (GMT) or Standard Time,
which is the time (calculated from the position of
the Sun) at Greenwich, London, which is on the
prime meridian. Zonal Standard Time is the mean or
standard time within a longitudinal zone of 15°, which is the
area between one meridian (a multiple of 15) and the one
Use your atlas to
locate these places.
(i) Georgetown
(Guyana,
located at 6*46'N (readas 6 degrees and 46 minutes
north) and 58°10'W. (ii) Toronto (Canada) is
43°39'N and 7920 W (11) Sydney (Australia) is
33°52'S and
151°10'5
15° east or west
of it.
World time is divided into 24 Standard Time Zones.
Areas centred on the prime meridian have the same time
as Greenwich. Travellers moving from one zone to
another have to adjust their watches. Time zones to the
west of Greenwich are behind GMT and times zones
east of Greenwich are ahead of GMT.
