Compass Flashcards
Define geomatics
Collecting, analysing, and interpreting data related to the earth’s surface
Define technology
Techniques, methods, and processes used in the production of goods or services
What are the 3 principles of tech?
- how we use it
- why it works
- how well it works
Define definition
the position of one point in relation to another point
What are the 2 types of direction?
Relative: related to a specific object
Absolute: based on a fixed reference frame (ex: north)
Explain a compass
Device with a magnetized needle that aligns itself to the earth’s magnetic poles
Explain magnetic declination/variation
The angle between magnetic north and true north - absolute direction. Positive if needle moves to the right and negative if needle moves to the left.
Three types of North direction
true north: the direction of the north pole
magnetic north: direction of the magnetic north pole
grid north: the direction northwards along the grid lines of a map projection
Define isogonic lines
Contour lines that connect points of equal magnetic declanation
What are the factors of magnetic declination?
location, secular change, solar magnetic activity, local magnetic anomalies, altitude, and diurnal change
What causes declination to change overtime?
Variations in the flow of molten iron in earth’s outer core, resulting in changes in the orientation of earth’s magnetic field
Explain magnetic deviation
Errors in a compass by local magnetic fields - needed if accuracy is to be calculated
Define diurnal change
Fluctuations that occur daily - negligible in tropical and temperate latitudes
Explain magnetic inclination
The angle made between the horizontal plane and magnetic needle of a compass
Alternatives to compasses
Gyrocompass: uses the rotation of the earth to find true north and unaffected by materials
GPS
