The maximum distance at which a given object can be seen, limited by the atmospheric transmission. The distance is such that the contrast of the object with its background is reduced by the atmosphere to the contrast threshold value for the observer. This term should not be confused with VISIBILITY.
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MOMENT OF INERTIA
The quantity obtained by multiplying the mass of each small part of a body by the square of its distance from an axis, and adding all the results.
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COMPRESSED AIR
Air at any pressure greater than atmospheric pressure.
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AIR BREATHER
A device permitting air movement between atmosphere and the component in/ on which it is installed.
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GREENWICH HOUR ANGLE
Angular distance west of the Greenwich celestial meridian; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of the Greenwich celestial meridian and the hour circle of a point on the celestial sphere, measured westward from the Greenwich celestial meridian throug
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HARPOON LOG
A log which consists of a rotator and distance registering device combined in a single unit, which is towed through the water. The TAFFRAIL LOG is similar except that the registering device is located at the taffrail, with only the rotator in the water.
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SHEAR RATE
The difference between the velocities along the parallel faces of a fluid element divided by the distance between the faces.
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ATMOSPHERE
Is the mixture of gases and water vapor surrounding the earth.
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HAZE
Fine dust or salt particles in the air, too small to be individually apparent but in sufficient number to reduce horizontal visibility and give the atmosphere a characteristic hazy appearance which casts a bluish or yellowish veil over the landscape, subduing its colors. This is sometimes called a dry haze to distinguish it from damp haze, small water droplets or very hygroscopic particles in the air, smaller and more scattered than light fog.
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HEIGHT OF TIDE
Vertical distance from the chart sounding datum to the water surface at any stage of the tide. It is positive if the water level is higher than the chart sounding datum. The vertical distance from the chart sounding datum to a high water datum is called RISE OF TIDE.
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PRESSURE GAGE
Pressure differential above or below atmospheric pressure.
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