Adele is back!Ahead of her anticipated album release, the 33-year-old singer is reminding everyone just how talented she is (not that we the reminder) with a two-hour primetime special on CBS, and only ET has the exclusive first look at one of her stunning performances.In the sneak peek, Adele — as glamorous as ever in a fitted black mermaid gown and her signature bun, as well as sparkly gold galaxy earrings — steps up to the mic in front of a pristine evening at the Griffith Observatory in the