Wolves howl at night because that is when the pack is active and sound carries furthest. They point their heads up because it projects the sound, not because anything is up there.

No study has found more howling at full moon. The image is a nineteenth-century illustration convention that hardened into a fact, helped along by the werewolf. Wolves howl to locate each other and to advertise territory, and a tipped-back head is simply better acoustics.