Of these elements, temperature and wind have the greatest affect on sound speed. Relative humidity changes produce only minimal sound speed changes.
Temperature normally decreases with height through the atmosphere.
This decrease in temperature causes sound waves to bend upward, away from the ground. This action is good with regard to blast waves, because blast noise is directed upward. Wind direction and speed can have a positive or a negative effect on blast waves. The wind may aid in pushing a blast wave in a direction where the noise level can produce damage, or it may retard the blast wave. The vector is the azimuth of interest.