What is the primary factor that defines detonation velocity?

Detonation velocity is fundamentally characterized by the speed at which the shock wave travels through the explosive material, which directly correlates to how quickly the surrounding atmosphere is displaced following a detonation. This rapid displacement of air is a key indicator of the explosive's effectiveness and the power of the detonation.

When an explosive detonates, it produces a high-velocity shock wave that compacts the surrounding air, creating a sudden increase in pressure. This phenomenon dictates not only the destructive potential of the explosive but also how that energy propagates outward, which is crucial in various applications such as demolition, military operations, and mining.

The other options address different aspects of explosives but do not accurately define detonation velocity. The speed at which an explosive burns pertains to its deflagration rate, the force exerted involves the overall energy output or pressure generated during the explosion, and the temperature at which an explosive detonates relates to its sensitivity and stability rather than the velocity of the detonation itself. Thus, the primary aspect that exemplifies detonation velocity is indeed the speed at which the atmosphere is displaced by the pressure wave generated during the explosion.