This paper deals with an experimental study regarding the spatial-temporal evolution of single wire explosions in air and water at atmospheric pressure. Experiments were carried out with a microsecond timescale pulsed current source under 500 J stored energy. The morphology of the exploding wire with different discharge type, wire material, insulating coat, and ambient medium was intensively observed via self-emission images. The results revealed that the plasma radiation of wire explosion in air mainly contained two stages: initial intense radiation from optically thick plasma, and later decaying radiation from expanded arc-like plasma. A hollow structure was observed in a Cu exploding wire in air, and the plasma channel tended to develop inside it. As for W case, there would always be a core-corona structure, resulting in lower expansion rate and shock wave strength. Moreover, the plasma radiation of the underwater wire explosion was mainly determined by two factors: expansion rate and chemical reaction. The expansion rate of the radiant region in water was only 10-1 mm μs-1 level (1 mm μs-1 level for air), leading to the lagging radiation. No noticeable difference in morphology was found between Cu and W wire explosions in water. Particularly, the Al wire explosion generated a bright light emission due to chemical reactions. Finally, radiative characteristics in an exploding wire were preliminarily concluded and existing problems proposed.