Terrestrial magnetism

Question 1

what is the magnetic equator?

Answer 1

halfway between north and south magnetic poles

no dip

Question 2

magnetic dip

Answer 2

angle between magnetic field line and the local horizon
vertical component(Z) swell as horizontal(H)
z greater near poles and 0 at magnetic equator so more dip at poles

Question 3

where is a compass least accurate and why?

Answer 3

poles
more dip
compass detects horizontal component which is less at the poles due to dip so compass less accurate

Question 4

long term magnetic changes- secular

Answer 4

poles move 10Nm per year

airway directions and runway headings can change

Question 5

short term magnetic changes

Answer 5

predictable-annual changes due to elliptical orbit
diurnal changes due to ionosphere height

unpredictable- changes due to solar activity, could change north up to 45Nm during a day

Question 6

magnetic variation

Answer 6

local angular difference between magnetic and true

easterly variation positive, westerly neg

Question 7

variation east

Answer 7

magnetic least

Question 8

variation west

Answer 8

magnetic best

Question 9

isogonal

Answer 9

line of equal magnetic variation on charts

Question 10

agonal

Answer 10

line of no magnetic variation