Evection: A perturbation of the Moon depending upon the alternate increase and decrease of the eccentricity of its orbit, which is always a maximum when the Sun is passing the Moon's line of apsides and a minimum when the Sun is at right angles to it. The principal constituents in the tide resulting from the evectional inequality are <2, 82, and D1.

 

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Evection: A perturbation of the Moon depending upon the alternate increase and decrease of the eccentricity of its orbit, which is always a maximum when the Sun is passing the Moon's line of apsides a . . . View Full Definition

RHO: Larger lunar evectional diurnal constituent. Speed = T – 3s + 3h – p = 13.471,514,5° per solar hour.

Lambda (82): Smaller lunar evectional constituent. This constituent, with <2, :2, and (S2), modulates the amplitude and frequency of M2 for the effects of variation in solar attraction of the Moon. This . . . View Full Definition

Nu: Larger lunar evectional constituent. See lambda. Speed = 2T – 3s + 4h – p = 28.512,583,1° per solar hour.