If you've gone to the place on the Citadel where it starts playing a sad song, then go there.

Get an explosive weapon (grenades,fuel rod gun, rocket launcher, etc).

Go to the part where the ramp is to go up to the place where the song plays.(sorry I'm not being specific).

Get your grenades or whatever and look down at the orange clouds and throw your grenade (doesn't matter what kind) and just give it minute.

If you wait long enough, the clouds will flash up into a blood red.

This can be done several times.