Air burst An air burst is the detonation of an explosive device such as an anti - personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor piercing explosion . The principal military advantage of an air burst over a ground burst is that the energy from the explosion ( as well as any shell fragments ) is distributed more evenly over a wider area ; however , the peak energy is lower at ground zero . The term may also refer to naturally occurring air bursts arising from the explosions of incoming meteor s as happened in the Tunguska event , the Curuçá River event , and the Chelyabinsk meteor event . History . Air burst artillery has a long history . The shrapnel shell was invented by Henry Shrapnel of the British army in about 1780 to increase the effectiveness of canister shot . It was widely used by the time of the War of 1812 and stayed in use until it was superseded during the First World War . Modern shells , though sometimes called " Shrapnel shells " , actually produce fragments and splinters , not shrapnel . Air bursts were used in the First World War to shower enemy positions and men with shrapnel balls to kill the largest possible number of them with a single burst , assuming that the burst was directly in front of the trench in which the men were positioned . When infantry moved into deep trenches , shrapnel shells were rendered useless and high - explosive shells were used to attack field fortifications and troops in the open . The time fuses for the shells could be set to function on contact or in the air . During the Second World War , a " Variable Time Fuse " was developed . This fuse could not be set by the gun detachment but was controlled by a doppler radar device which caused the shell to explode when near the target . During the Vietnam War , air bursting shells were used to great effect to defend US Army bases . This tactic was known as ' Killer Junior ' when referring to 105 mm or 155 mm shells , and ' Killer Senior ' when employed with larger howitzers . Some anti - personnel land mine s such as the " Bouncing Betty " fire a grenade into the air before it detonates , causing the fragments to fly out at waist level , increasing the blast radius . A relatively recent example of airburst munitions is the VOG - 25P " jumping " 40mm caseless grenade , which contains a secondary charge to launch it up to 1 . 5 meters above its point of impact before the main charge detonates . Another recent development is computer programmable rounds . Weapons using this new technology include the XM29 , XM25 , XM307 , K11 , and PAPOP , all of which are in various stages of prototyping or testing . Nuclear weapons . The air burst is usually several hundred to a few thousand feet ( 100 to 1000m ) above the hypocenter to allow the shockwave of the fission or fusion driven explosion to bounce off of the ground and back into itself , creating a shockwave that is more forceful than one from a detonation at ground level . This " mach stem " only occurs near ground level , and is similar in shape to the letter Y when viewed from the side . Airbursting also minimizes fallout by keeping the fireball from touching the ground , limiting the amount of debris that is vaporized and drawn up in the radioactive debris cloud . For the Hiroshima bomb , an air burst 1 , 800 – 2 , 000 feet ( 550 – 610m ) above the ground was chosen " to achieve maximum blast effects , and to minimize residual radiation on the ground as it was hoped U . S . troops would soon occupy the city " . Tactics . Air bursts are used primarily against infantry in the open or unarmored targets , as the resulting fragments cover a large area but will not penetrate armor , entrenchments , or fortifications .