What does the agonic line on an isomagnetic...

What does the agonic line on an isomagnetic...

Question 1 of 310489B0QTJajMTlqLtSEk94T

What does the agonic line on an isomagnetic chart indicate?

Question 1 of 31048

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What does the agonic line on an isomagnetic chart indicate?

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🔍 Key Concepts

• Magnetic variation (declination) – the angle between true north and magnetic north • Isogonic lines – lines on a chart connecting equal magnetic variation • How an agonic line relates to isogonic lines on an isomagnetic chart

💭 Think About

• First recall what an isomagnetic (or isogonic) chart is used for in navigation and what quantity it displays. • Ask yourself: if most lines show equal amounts of variation, what would be special about one particular line that’s given its own name (agonic)? • Consider the difference between a place where variation is changing over time and a place where the amount of variation itself has a certain key value.

✅ Before You Answer

• Verify the definition of magnetic variation: angle between true and magnetic meridians. • Check how isogonic lines are labeled (e.g., 2°E, 5°W) and think about what value would make a special line. • Be sure not to confuse annual change in variation with the value of variation itself at a location.