The process by which the pressure disturbance from a passing aircraft is distorted as it propagates away from the aircraft, causing the signature to stretch out in duration and length, lose detail, and form shock waves.

Growing older.

All irreversible structural changes that occur in a precipitate after it has formed.

Allowing a permanent magnet, capacitor, meter, or other device to remain in storage for a period of time, sometimes with a voltage applied, until the characteristics of the device become essentially constant.

Change in the magnetic properties of iron with passage of time, for example, increase in the hysteresis.

1. The changing of the characteristics of a device due to its use.

2. Operation of a product before shipment to stabilize characteristics or detect early failures.

1. Change in the properties of any substance with time.

2. Change occurring in powders or slips with the passage of time.

3. Curing of ceramic materials, such as clays and glazes, by a definite period of time under controlled storage conditions.

1. Change in properties of an alloy or metal which generally proceeds slowly at room temperatures and faster at elevated temperatures.

2. Strain relief, occurring through long storage outdoors under varying temperatures, of iron castings intended for use as toolroom plates or lathe-bed supports.

3. A second heat treatment of an alloy at a lower temperature, causing precipitation of the unstable phase and increasing hardness, strength, and electrical conductivity.

The slowing down of neutrons.