From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The Kiai (気合い; Literally meaning "Yell") is an offensive technique used by many fighters.
The Kiai was a very powerful, white-clear force emitted from the user's body that inflicted severe damage to the surrounding area. Alternatively, this force could be used to dispel weaker attacks, as shown by Tenshinhan on a few occassions. The blast's power, speed, range, and force varied based on its user, however, there were also variations of the technique that had been shown to have different effects. For example, Goku's version was oftentimes projected from his hands, but it could also be released from his eyes. Tenshinhan's version was thought to be released from his hands, and could deflect and nullify a Ki Blast with no damage done to his surroundings. Oob's variation, however, seemed to channel and release the technique from his entire body, and was shown to be able to lift the whole tiled flooring of the Tenkaichi Tournament Arena. Furthermore, unlike the other variations, the power of Oob's Kiai was fueled by his rage rather than the concentration of his ki. Artificial Human No. 17 could fire a Kiai from his palm that exploded upon contact with his opponent, and he used it in lieu of energy attacks.