# IONOSPHERIC REFRACTION

Change in the propagation speed of a signal as it passes through the ionosphere

## Related Terms

### COLD CRANKING SIMULATOR

An intermediate shear rate viscometer that predicts the ability of an oil to permit a satisfactory cranking speed to be developed in a cold engine. (CCS)

### GROUND LOG

A device for determining the course and speed over the ground in shallow water consisting of a lead or weight attached to a line. The lead is thrown overboard and allowed to rest on the bottom. The course over ground is indicated by the direction the line tends and the speed by the amount of line paid out in a unit of time.

### HARMONIC

1. A sinusoidal quantity having a frequency that is an integral multiple of the frequency of a periodic quantity to which it is related. 2. A signal having a frequency which is an integral multiple of the fundamental frequency.

### BROOKFIELD VISCOSITY

Apparent viscosity in cP determined by Brookfield viscometer, which measures the torque required to rotate a spindle at constant speed in oil of a given temperature. Basis for ASTM Method D 2983; used for measuring low temperature viscosity of lubricants.

### GUST

1. A sudden brief increase in the speed of the wind of more transient character than a squall, and followed by a lull or slackening of the wind. 2. The violet wind or squall that accompanies a thunder- storm.

### HOP

Travel of a radio wave to the ionosphere and back to earth. The number of hops a radio signal has experienced is usually designated by the expression one-hop, two-hop, multihop, etc

### HOMING

Navigation toward a point by following a signal from that point. Radiobeacons are commonly used for homing.

A tidal current setting in a direction approximately opposite to the heading of a vessel. One setting in such a direction as to increase the speed of a vessel is called a FAIR TIDE. One abeam is called a BEA

### REFRACTION

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

### HYPERSONIC

Of or pertaining to high supersonic speed, of the order of five times the speed of sound, or greater

### Related questions

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