Yellow, Blue, Orange, Green.....

Does anyone *really* pay attention to the terror alert level anymore? Each month the administration picks a new color.... let's move to orange, no yellow, no orange.

Let's be real for a second. The reasons I'm aware of level changes are because:

1) I'm forbidden to open my office window when the alert hits orange and the building engineers stroll the corridors searching for the rebels breathing in fresh air.

2) I live in D.C. and sometimes overhear hysterical alarmists on the metro, freaking out into their cellphones to relatives in Nebraska about how they've got to stop riding the metro because terrorist threats make it a prime target.

Does anyone out there know what the colors MEAN?