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The following are different factors that affect the diurnal variation in magnetic declination. The condition which may result in the maximum variation is _______________.
at the Magnetic Poles during winter
at the Equator during summer
at the Magnetic Poles during summer
at the Equator during winter
at the Magnetic Poles during summer
The diurnal variation of magnetic declination refers to the daily oscillation of the magnetic needle. This variation is significantly influenced by the intensity of solar radiation and the proximity to the magnetic poles, reaching its peak magnitude at the magnetic poles during the summer season.
The diurnal variation of magnetic declination refers to the daily oscillation of the magnetic needle. This variation is significantly influenced by the intensity of solar radiation and the proximity to the magnetic poles, reaching its peak magnitude at the magnetic poles during the summer season.
╬Ф╬┤тИЭSolar┬аIntensity├ЧMagnetic┬аField┬аStrength
Diurnal variation is primarily caused by solar radiation affecting the Earth's ionosphere, creating electric currents that induce secondary magnetic fields. Because these effects are linked to the angle of solar incidence and the concentration of magnetic field lines, the variation is most pronounced where solar activity is high and the magnetic flux density is greatest, which occurs at the magnetic poles during the summer solstice.
Diurnal variation is greater in summer than in winter.
Variation is greater in the day than at night.
Variation is more pronounced at the magnetic poles than at the equator.
The range of oscillation follows the intensity of ultraviolet radiation reaching the ionosphere.
Helps in applying corrections to compass surveys.
Understanding the pattern improves accuracy in cadastral surveying.
Introduces time-dependent errors in magnetic bearings.
Requires local correction tables for precise work.
Geodetic surveying
Geophysical exploration
Navigation and cartography
Diurnal variation is minimum at the equator and maximum near the magnetic poles.
Option B (at the Equator during summer) represents the region of least variation rather than the maximum.
The variation also depends on the 11-year sunspot cycle.
C is correct тАФ The maximum diurnal variation of magnetic declination occurs at the magnetic poles during summer due to the combined effect of higher solar exposure and the concentration of Earth's magnetic flux lines.
Always remember that diurnal variation is directly proportional to solar activity; hence, it is always higher in summer and higher in the daytime compared to night.
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