Complex Mathematics For Mapping
Setting the scene
Not only do surveyors need to have knowledge of the land and how best to measure it, they also need to understand the intricacies behind mapping. Key features of maps are latitude and longitude.
An imaginary line around the centre of the earth is called the Equator. This is numbered as zero (0) degrees latitude. From here a number of parallel lines, with the most north point being the North Pole and most south point being the South Pole, are created. Each of these are numbered up to 90 degrees north and down to 90 degrees south.
Latitudinal lines are horizontal lines; they are north or south of the Equator and therefore create the Northern and Southern hemispheres.
There are four specific lines of latitude to remember;
- 0 degrees is the Equator
- 23.5 degrees north is the Tropic of Cancer and 23.5 degrees south is the Tropic of Capricorn
- 66.5 degrees to the north and south are the polar circles
- 90 degrees to the north and south are the poles
A series of radiating lines run vertically around the earth connected at both ends are called longitudinal lines. The primary line of longitude is 0 degrees longitude, which runs through the Royal Observatory, Greenwich, England. Running east to west there are 180 degrees of longitude. These lines are called meridians.
Both longitude and latitude combine to form a grid pattern. Using the coordinates from these grids we are able to record the location of any feature on the surface of the earth.
Complete the following activities using the Canberra area satellite image provided:
- Write down the longitude and latitude for a – d marked on the map provided;
- Parliament House
- Old Parliament House
- Australian War Memorial d) National Capital Exhibition
- Canberra is a planned city. Choose three circles which have been created from its design and write down their longitude and latitude.
- Describe what you can see at 149 degrees 7’35”E, 35 degrees 17’32”S
Eg: The mark x on the diagram below is Latitude/Longitude (32 degrees South 142 Degrees East)
- Develop a practical knowledge of map reading
- Understand the difference between longitude and latitude, and why they are useful
- Learn the mathematical skills involved in map reading