INTRODUCTION
It is possible to convert an Adjustment Layer into a Layer Mask.  A black mask hides it’s linked layer from the layers below.  A white paint brush is used to reveal painted areas of the masked layer.  Brush sizes and some settings may vary with different pictures.  Get a free layer mask tool from http://graphicssoft.about.com/od/pselements/qt/layermasktool.htm.
The mask tool is not required for this lesson.

OPEN A PICTURE
Open Photoshop Elements in the Full Edit mode.  Click File + Open (or hold the Ctrl key and tap the O key) > select a picture such as a landscape with low clouds > click Open (becomes Background on the Layers palette) > click the blue bar above the picture and drag it halfway behind the palettes.

OPEN A SECOND PICTURE AND REMOVE BACKGROUND
Open a picture of a person or object that is tall and slender (Picture A) > use the Magic Wand tool to select the object (be sure “Add to selection” is selected on the Adjustments bar) > use the Quick Selection tool and Alt key to erase unwanted selections.  (If the background is selected instead of the object, click Select + Inverse to select the object) > select the Move tool and move the object onto the background picture > close Picture A without saving > drag the combined picture to the center > Ctrl 0 to enlarge > move the object until a corner is visible and hold the Alt key as you reduce the size (move and reduce size until the picture is about ¼ the height of the background picture) > on the Layers palette, name it Object.  Select the Move tool > move Object up with top above the clouds (if possible) and bottom below buildings or mountains > reduce the opacity to about 50% to reveal the outline of the skyline.

CREATE AN ADJUSTMENT LAYER ON THE LAYERS PALETTE
With Object the active layer, click the “Create adjustment layer” icon on the Layers Palette + Brightness/Contrast > accept the defaults > click OK.  Drag Object above the adjustment layer > hold the Alt key and click the horizontal line between the top 2 layers (links the layers and tricks PE6 into thinking the Adjustment layer is a Layer Mask).

PAINT OUT THE BOTTOM PART OF OBJECT AND SOME CLOUD
Select the Layer Mask (click the right square on the Adjustment layer) > select a black color for the Foreground color (bottom of the Tools bar) > select the Brush tool (on the Tools bar) > right-click the picture and select a hard edge tool such as 13 > paint Object (carefully only paint below the edge of the skyline) > tap bracket keys to change the brush size (notice that the black paint hides Object) > select Object (click it’s name) > change Opacity to 100% > select the Layer Mask > select the Brush tool and paint just a puff of cloud (looks like Object is surrounded by clouds) > change foreground color to white and paint over unwanted cloud areas.

CONCLUSION
This technique can be applied to any part of a copy of a layer or any second layer.  Any filter or Adjustment layer can be applied to the top layer.  The original is not changed if final file is saved under a different name.