3. Magnetism And Compasses Flashcards
What is true north?
True north is the direction that points directly towards the geographic North Pole
True north is a fixed point on the globe
What is magnetic north?
Magnetic north is the direction that a compass needle points to as it aligns with the Earth’s magnetic field
The Magnetic North Pole shifts and changes over time in response to changes in the Earth’s magnetic core.
It is not a fixed point
What is magnetic variation?
Is the angle between magnetic north and true north.
sometimes called magnetic declination
What is Deviation?
The angle between Magnetic North and Compass North measured in degrees East or West from Magnetic North
Magnetic compass errors?
Manufacture.
Irregularities and Fluctuations in Earth’s Magnetic Field.
What are isognals?
VARIATION SHOWN ON A MAP IN DIFFERENT WAYS INCLUDING ISOGONALS
Lines across a map joining points of equal variation
How do we represent variation on a map? (3)
Isogonal
Marginal diagram
Double compass rose
What is compass north?
Magnetic north corrected for deviation
When is the magnetic compass most effective? At the equator or the Magnetic Poles?
Equator (because at the equator, all of the planet’s magnetic field lines are horizontal and parallel to Earth’s surface)
What is VISUAL NAVIGATION?
a technique often employed in light aircraft, which operate at relatively low speeds and heights, when weather is good and visual contact can be maintained with the ground for most of the flight.
It is carried out using maps and following features such as roads, railways, rivers and other visual geographical features on the ground
What is Variation?
The angular difference (expressed in degrees, minutes and seconds) between true
north and magnetic north as measured by a magnetic compass at a particular location on the surface of the Earth.
What is Deviation?
The angle between Magnetic North and Compass North measured in degrees East
or West from Magnetic North.
