A Accuracy: a measure of how close the results of an experiment are to the true value; a measure of the correctness of the result. Antenna: a device for radiating or receiving radio waves. Amplitude: the maximum disturbance or distance from the constant point. Asthenosphere: layer of the Earth found 100-500 km below the Earth's surface that yields to persistent stresses more than the rigid crust or the core. Atmosphere: the whole mass of air surrounding the earth.