The angle through which a ray is bent by refraction
Related Terms 
HARMONIC FUNCTION
Any real function that satisfies a certain equation. In its simplest form, as used in tide and tidal current predictions, it is a quantity that varies as the cosine of an angle that increases uniformly with time

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

GRID RHUMB LINE
A line making the same oblique angle with all grid meridians. Grid parallels and meridians may be considered special cases of the grid rhumb line.

GRID MAGNETIC ANGLE
Angular difference in direction between grid north and magnetic north. It is measured east or west from grid north. Grid magnetic angle is sometimes called GRID VARIATION or GRIVATION.

HORIZONTAL DANGER ANGLE
The maximum or minimum angle between two points on a chart, as observed from a vessel, indicating the limit of safe approach to an offlying danger.

PARTICLE EROSION
Occurs when fluidentrained particles moving at high velocity pass through orifices or impinge on metering surfaces or sharp angle turns.

HOUR ANGLE
Angular distance west of a celestial meridian or hour circle; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of a celestial meridian or hour circle and the hour circl

REFRACTION
The change of direction or speed of light as it passes from one medium to another.

INCLINATION OF AN ORBIT
1. See INCLINATION, definition 2. 2. As defined by the International Telecommunication Union (ITU), the angle determined by the plane containing an orbit and the plane of th

INCLINATION
1. The angle which a line or surface makes with the verti cal, horizontal, or with another line or surface. 2. One of the orbital elements (parameters) that specifies the orientation of an orbit. It is the angle between the orbital plane and a reference plane, the plane of the celestial equator for geocentric orbits and the ecliptic for heliocentric orbits.
