10 Terrestrial Magnetism

Question 1

What colour is associated with each magnetic pole and which way do the lines of magnetic flux travel?

Answer 1

• North: Blue
• South: Red
• Flux lines travel out of the south mag pole and into the north mag pole

Question 2

What are the following regarding the total magnetic field:

• Components
• Difference between the components
• Where are they strongest

Answer 2

• Horizontal component (H): strongest at the mag equator
• Vertical component (Z): strongest at the mag poles
• Difference is called Dip (max value 90 degrees)

Question 3

Describe what causes the following regarding changes to the Earth’s magnetic field:

• Long term changes
• Short term predictable changes
• Short term unpredictable changes

Answer 3

• The mag poles are currently moving by 10nm per year. Once every 450,000 years the mag poles switch.
• Annual changes due to the Earth’s orbit of the Sun, coming closer and further away. Diurnal changes due to the change in height of the ionosphere as the Earth rotates.
• Unpredictable solar wind activity