The imaginary line on the ground, all points of which are at the same elevation above or below a specified datum. 
The imaginary line on the ground, all points of which are at the same elevation above or below a specified datum. 
Related Terms 
MEAN WATER LEVEL LINEThe line formed by the intersection of the land with the water surface at an elevation of mean water level. 
RIDGE

CONTOUR LINEA line connecting points of equal elevation or equal depth. One connecting points of equal depth is usually called a depth contour, but if depth is expressed in fathoms, it may be called a fathom curve or fathom line. 
GRADIENT WINDAny horizontal wind velocity tangent to the contour line of a constant pressure surface (or to the isobar of a geopotential surface) at the point in question. At such points where the wind is gradient, the Coriolis force and the centrifugal force together exactly balance the horizontal pressure force. 
HIGH WATER LINE

DOUBLETHEODOLITE OBSERVATIONA technique for making windsaloft observations in which two theodolites located at either end of a base line follow the ascent of a pilot balloon; synchronous measurements of the elevation and azimuth angles of the balloon, taken at periodic intervals, permit computation of the wind vector as a function of height. 
COASTAL BOUNDARYA general term for the boundary defined as the line (or measured from the line or points thereon) used to depict the intersection of the ocean surface and the land at an elevation of a particular datum, excluding one established by treaty or by the U.S. Congress. 
DIFFERENTIAL LEVELINGA surveying process in which a horizontal line of sight of known elevation is intercepted by a graduated standard, or rod, held vertically on the point being checked. 
HIGH WATER MARKA line or mark left upon tide flats, beach, or alongshore objects indicating the elevation of the intrusion of high water. It should not be confused with the MEAN HIGH WATER LINE or MEAN HIGHER HIGH WATER LINE 
DIP

MarineProHelp 2018  2020