This spell reverses gravity in the spell’s area, causing all unattached objects and creatures within it to fall upward and reach the top of the area in 1 round. If some solid object (such as a ceiling) is encountered in this fall, falling objects and creatures strike it in the same manner as they would during a normal downward fall. If an object or creature reaches the top of the area without striking anything, it remains there, oscillating slightly, until the spell ends. At the end of the spell duration, affected objects and creatures fall downward.
Provided there’s something for them to hold onto, creatures caught in the area can attempt Reflex saves to secure themselves when the spell strikes. Creatures who can fly or levitate can keep themselves from falling.