https://thereader.mitpress.mit.edu/devastating-effects-of-nuclear-weapons-war/
The most widespread damage to buildings occurs in an air burst, a detonation thousands of feet above the target. The blast wave from an air burst reflects off the ground, which enhances its destructive power.
A ground burst, in contrast, digs a huge crater and pulverizes everything in the immediate vicinity, but its blast effects don’t extend as far. Nuclear attacks on cities would probably employ air bursts, whereas ground bursts would be used on hardened military targets such as underground missile silos.
原來兩種burst都有用