What do the spires represent?

Thunderbird contrails in a "bomb burst" maneuver

Once the decision was made to incorporate vertical elements, the number three became important. "Three" is resonant with significant associations for the Air Force, including the three core values of today: Integrity first, Service before self, and Excellence in all we do. It is also the smallest number of elements needed to define and enclose a space.

Thats a good question! I'll have to ask security next time..