Essential Geographic and Maritime Navigation Terms

Geographic Coordinates and Earth's Geometry

• Poles: The extreme points of Earth's diameter that form the axis of rotation.
• Equator: The circle of the Earth perpendicular to the line of the poles.
• Great Circle: The intersection of a sphere with any plane passing through its center.
• Earth Meridians: Great circles that pass through Earth's poles and cross the Equator perpendicularly.
• Local Meridian: The terrestrial meridian passing through a specific place; any meridian is divided by the poles into two equal parts of 180°.
• Greenwich Meridian: Passes through the observatory of the same name; it is also called the 0° meridian or Prime Meridian.
• Parallels: Smaller circles that are parallel to the Equator.

Maritime Navigation and Port Data

Port of Valparaiso:
Latitude: 33° 01' 33" S
Longitude: 71° 38' 22" W

Tidal Phenomena and Ocean Dynamics

• Swell: Vertical oscillation of the water during a relatively short period and high relative velocity.
• Tide: Periodic oscillation of sea level resulting from the gravitational pull of the Moon and Sun acting on the rotating Earth.
• Tidal Range: The difference in height between high tide and low tide in a single day.
• Diurnal Inequality: The difference in height between the levels of two daily high tides or two successive low tides.
• Tidal Wave: A long wave originating from tide-producing forces, manifested in the rise and fall of the sea.
• Diurnal Day: One high tide and one low tide per cycle, occurring over a period of 24 hours and 50 minutes.
• Semidiurnal: Two high tides and two low tides during two successive cycles (12 hours 25 minutes each), where amplitudes are substantially similar.
• Mixed: Two high tides and two low tides during two successive cycles (12 hours 25 minutes each), where amplitudes show marked differences.

Lunar Cycles and Depth Measurements

• Syzygy: A Moon phase (full or new) when the Moon and Earth are aligned with respect to the Sun.
• Syzygy Tide: A tide that occurs during the full moon or new moon.
• Perigee: The point of the Moon's orbit that is closest to Earth.
• Apogee: The point of the Moon's orbit farthest from Earth.
• Ridges (Isobaths): Lines that connect points of equal depth.