. Coastal currents along the Atlantic coast of the United States. Ocean currents; Tides. 2 U. S. COAST AND GEODETIC SURVEY the line of zero velocity and the southerly setting or ebb velocities were plotted below this line. The velocities are given in Icnots, which is the unit generally used in measuring tidal currents and represents a velocity of 1 nautical mile per hour. Since a nautical mile has a length of 6,080 feet, laiots may be converted into statute miles per hour by multiplying by , or into feet per second by multiplying by The curve of the reversing current resembles the ti
. Coastal currents along the Atlantic coast of the United States. Ocean currents; Tides. 2 U. S. COAST AND GEODETIC SURVEY the line of zero velocity and the southerly setting or ebb velocities were plotted below this line. The velocities are given in Icnots, which is the unit generally used in measuring tidal currents and represents a velocity of 1 nautical mile per hour. Since a nautical mile has a length of 6,080 feet, laiots may be converted into statute miles per hour by multiplying by , or into feet per second by multiplying by The curve of the reversing current resembles the tide curve. The maximum velocity of the flood current, called the strength of flood, corresponds to the high water of the tide curve, while the maximum velocity of the ebb, called the strength of ebb, corresponds to the low water. The current day, like the tidal day, has a length averaging 24 hours and 50 minutes. The current curve shown in figure 1 represents the current near the surface in the axis of the channel of The Narrows. From observation and also from theory it is laiown that the tidal current extends from the surface to the bottom. In general it may be said that the velocity. Figure 1.—Current curve, The Narrows, New York Harbor, August 8-9, 1922. of the tidal current decreases from the surface to the bottom, the veloc- ity near the bottom being about two thirds that at the surface. But the effects of wind and fresh-water flow may bring about considerable variation in the vertical velocity distribution. The current in a channel is also characterized by a variation in the horizontal distribution of velocity. In a rectangular channel of miiform cross-section, the velocity is greatest in the center of thii channel, and decreases uniformly to both sides. Combining both the vertical and horizontal variations, it may be said that the average velocity of the current in a section of a regular channel is about three- quarters that of the central surface velocity. Wliere the c
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