Martel (missile) Martel (missile) The Martel is an Anglo-French anti-radiation missile (ARM). The name Martel is a contraction of "Missile, Anti-Radiation, Television", referring to the guidance options. There are two variants, the passive radar guided (AS 37) and the video guided (AJ 168). The aircraft that used these missiles were the Blackburn Buccaneer (up to three TV or four ARM variant), the SEPECAT Jaguar (two), the Mirage III/F1 (one or two), and the Hawker Siddeley Nimrod (at least one). The Martel was suited to anti-ship attack with its long range and heavy warhead. There was not, at the time, a small radar
Sound speed gradient Sound speed gradient In acoustics, the sound speed gradient is the rate of change of the speed of sound with distance, for example with depth in the ocean, or height in the Earth's atmosphere. A sound speed gradient leads to refraction of sound wavefronts in the direction of lower sound speed, causing the sound rays to follow a curved path. The radius of curvature of the sound path is inversely proportional to the gradient. When the sun warms the Earth's surface, there is a negative temperature gradient in atmosphere. The speed of sound decreases with decreasing temperature, so this also