Perigean spring tide
Maximum amplitude of the tide around the passage of the Moon at its perigee.
perigee
Closest point of the orbit to a focus.
PNA
Ports Normands Associés (associated Norman ports).
Polar axis
The Earth's axis of rotation.
Polar distance
Complement at 90° to the declination.
Priming
Period during which the amplitude of the tide increases between neaps and springs.
Proctor's rule
Geometric construction of the tide generating force.
PSMSL
Permanent Service for Mean Sea Level.