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The picture shows a 20 kiloton air burst at 540 meters, to optimize the area covered by at least 15 psi blast damage. Mach stem formation occurs when a blast wave reflects off the ground and the reflection catches up with the original shock front, therefore creating a high pressure zone that extends from the ground up to a certain point called ...
An anomalous feature of the blast was the formation of a precursor, a second shock front ahead of the incident wave. This precursor was formed when the shock wave reflected off the ground and surpassed the incident wave and Mach stem due to a heated ground air layer and the low burst height. [2]
The Mach angle is acute, showing that the body exceeds Mach 1. The angle of the Mach wave (~59 degrees) indicates a velocity of about Mach 1.17. In fluid dynamics, a Mach wave, also known as a weak discontinuity, [1] [2] is a pressure wave traveling with the speed of sound caused by a slight change of pressure added to a compressible flow.
This is caused by the nonlinear behavior of shock waves. When the blast wave from an air burst reaches the ground it is reflected. Below a certain reflection angle, the reflected wave and the direct wave merge and form a reinforced horizontal wave, known as the '"Mach stem" and is a form of constructive interference.
A blast wave reflecting from a surface and forming a mach stem. The air burst is usually 100 to 1,000 m (330 to 3,280 ft) above the hypocenter to allow the shockwave of the fission or fusion driven explosion to bounce off the ground and back into itself, combining two wave fronts and creating a shockwave that is more forceful than the one resulting from a detonation at ground level.
As a result of the data gathered on the size of the blast, the detonation height for the bombing of Hiroshima was set at 1,885 feet (575 m) to take advantage of the Mach stem blast reinforcing effect. [137] The final Nagasaki burst height was 1,650 feet (500 m) so the Mach stem started sooner. [138]
This phenomenon of a blast wave occurs when the blast reaches the ground and is reflected. Below a certain reflection angle the reflected wave and the incident wave merge and form a reinforced horizontal wave; this is known as the 'Mach stem' (named after Ernst Mach) and is a form of constructive interference and consequently extends the range ...
Operation Upshot–Knothole was a series of eleven nuclear test shots conducted in 1953 at the Nevada Test Site.It followed Operation Ivy and preceded Operation Castle.. Over 21,000 soldiers took part in the ground exercise Desert Rock V in conjunction with the Upshot-Knothole Grable shot. [1]