1.   By the time a cold snap hits and engineers adjust the antiquated burners and valves and pipes, a wave of warmer air rushes in.

2.   He declined to name any potential new destinations but added that he hopes some added service will be in place in time for the Christmas holiday air travel rush.

3.   When the weight is removed, air rushes back in, creating suction in the cleaning wand.

4.   A second shock wave, when air rushes back in, causes more damage.