Move through Autumn Plains until you get to the top of the stairs which lead down to Gulp's Overlook, the final level for this portion of the game. If you're not sure where this is, its just past the balcony which you glide from to get to Icy Speedway.
The wall on the left in this area is cracked and broken, unlike the wall on the right. Charge this wall to reveal a whirlwind which takes to a grassed area on the roof of the castle. From here, another whirlwind takes you up to the top of the castles tallest tower. Go to the edge that faces the three flags and look to the left.
Beyond the battlements below you (the domed roof which covers Zephyr is visible also), you should see two small grassy platforms stretching up out of the clouds. Glide from the tower down to the taller of these two platforms to get this trophy, and also one of the orbs for this level.