2. Imaginary lines of latitude and longitude on the Earth
Imaginary lines are drawn on maps to describe where places are on the Earth.
positions
These lines appear in the same positions on all maps
The Earth's axis goes through the centre of
the Earth from the North Pole to the South
Pole. The Earth rotates on this axis
The lines of latitude are parallel circles that
go horizontally around the Earth. They
south
indicate distance north or south from the
Equator. The Equator is the middle line that
divides the Earth into two equal parts. These
two parts are Northern Hemisphere and the
Southern Hemispheres
The lines of longitude go vertically from pole to
pole. Every point on Earth is measured iin
n
terms of how far east or west it is from the
line of zero longitude. This line is called the Greenwich Meridian because it passes
through Greenwich in England
The movements of the Earth
Celestial bodies move in the sky. For this reason, we know that the Earth and
the Moon move in the sky. This happens even if we cannot feel the movement. The
Earth has two movements, called orbit and rotation.
orbit.
The Earth is a planet which moves around the Sun. This movement is called orbit.
The Earth takes 365 days and 6 hours (one year) to complete one orbit of the Sun.
The amount of light and heat received form the Sun is not equal everywhere on Earth
because of the Earth's tilt. This causes different climates in different areas of the
world. It is also responsible for the changes in season during the year: spring, summer,
2
3. hemispheres.
autumn and winter. The seasons happen at different times in the two hemispheres.
When it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere.
itself, rotation.
When the Earth rotates on itself, the movement is called rotation. The Earth
takes 24 hours or one entire day, to rotate on itself. This movement causes us to
night.
have day and night.
Because the Earth is round, the Sun can illuminate only one area of it. The other
the
area of the planet is in the shade. It is day time in the area that the Sun is
illuminating. It is night time in the area that is in the shade. When the Earth rotates,
the area that is illuminated gradually gets darker. The area that is in the shade
gradually gets illuminated.
Maps,
Maps, scale and projections
A map is a two dimensional description of a specific area of land. Maps help
geographers understand in a visual way, important things about the surface of the
Earth. They have been used by humans for hundreds of years, but it is impossibility
impossibility
of recreating the surface of a round planet on a flat map. Maps are not perfect!
3
4. Maps can represent a variety of
information. This information includes things
such roads, tourist attractions or towns.
Something can help us understand maps. For
example, title, legend, scale, geographic
coordinates or projection. The objects on a
map are represented using symbols. A symbol
picture
is a picture on the map that represents
something in the real world. To read a map
you need to understand compass directions
(showing which way is up —North-), grid references (numbered squares), the map's key
North-
(the reader knows what the symbols on the map represent) and scale (the reader can
(the
translate distances shown on the map into distances on the ground). Make sure
ground).
the
you read the title of a map before you start to use it (eg land use or vegetation cover).
This will give you a general idea about the information it stores.
The scale below is for a 1:50,000 scale The scale is the proportion between the real size of
map. At this scale, 1 cm on the map
represents 50,000 cm on the ground the represented territory and the corresponding size on
(= 500 m or 0.5 km)
the map. For example, your map has a scale of 1:25 000,
which means that every 1 cm on the map represents
25000
25000 of those same units of measurement on the
ground (for example, 25000 cm = 250 metres). There
25000
are three common methods used by map makers to
depict
depict scale: graphic method and fractional method.
3-
A map projection is any of many methods used to represent the 3-dimensional
2-
surface of the Earth on a 2-dimensional plane in cartography. There are three map
plane.
projection types: cylindrical, cone and plane.
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