Also found in: Dictionary.
Related to annual variation: seasonal variation
annual variation[′an·yə·wəl ver·ē′ā·shən]
The change in the right ascension and declination of a star during one year, due to the combined effect of the star's proper motion and the precession of the equinoxes.
A component in the change with time in the earth's magnetic field at a specified location that has a period of 1 year.
The quantum of yearly change in variation at a place. This is normally indicated on the bottom of a map or chart and must be added/subtracted to/from the figure given on the map after taking into consideration the number of years elapsed since the last survey for the map. Variation is the angular difference between the direction of true north and magnetic north at any given point.