Direction along the gravity field linesthe Earth's gravity field lines.
When in water it is perpendicular to the sea level.
In most practical applications this would be a straight line pointing at Earth Centreat Earth's centre.
See also
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Direction along the gravity field linesthe Earth's gravity field lines.
When in water it is perpendicular to the sea level.
In most practical applications this would be a straight line pointing at Earth Centreat Earth's centre.
...