apparent solar time
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apparent solar time:see solar timesolar time,
time defined by the position of the sun. The solar day is the time it takes for the sun to return to the same meridian in the sky. Local solar time is measured by a sundial.
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apparent solar timeTime measured by reference to the observed (apparent) motion of the Sun, i.e time as measured by a sundial. The apparent solar day is the interval between two successive apparent noons. The time on any day is given by the hour angle of the Sun plus 12 hours. Because the Sun's motion is nonuniform (see mean Sun) apparent solar time does not have a constant rate of change and cannot be used for accurate timekeeping. The difference between apparent time and mean solar time is the equation of time.
Apparent Solar Time
(or true solar time), a system of reckoning time in which the length of the day is taken to be equal to the interval between two successive passages of the sun’s center through the southern portion of the celestial meridian (upper culminations). Apparent solar time is reckoned from the upper culmination of the sun’s center, that is, from apparent noon. The length of the apparent solar day varies during the course of a year.