The spatioles: being in advance or late because of the declination.

The times of the water spatioles depend on the positions and declinations of the Moon, and of the Sun respectively.

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This is the second of two related annexes,
possibly to be read in the top-down order:
spatioles - introduction;
water spatioles - leads, lags.

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In a semi-diurnal basin, in the northern hemisphere, let's consider a tide generating celestial body (either Moon, or Sun), when it is above the meridian (curve A, in the graph below). If it presents a north declination, it acts early. If it has a south declination, it acts late.

Consider the generating body above the opposite meridian (curve B). If it presents a north declination, it acts late. If it has a south declination, it acts early.

The graph of the spatioles at Venice.

Abscisses: values of the times (minutes).
Ordinates: values of declination (degrees).

>> passage of time >>

Above, I present the provisional graph (updated on March 2012), valid for the lagoon of Venice, of the advance and delay (in minutes), of the centres of the times of the spatioles, due to the declination of the respective generating mass (either Moon, or Sun).

The bar line on the graph represents the passage of one of the two celestial bodies, either above the local meridian, or above the opposite one. The curve A (squares) represents the effect on the times during the passages above the local meridian; the curve B (lozenges), during the passages above the opposite meridian.