On Sun, Dec 21, 2003 at 05:03:32PM +0200, Alf C Stockton wrote:

I have two photos taken 6 months apart. Both were taken at 07:00 AM, of the sunrise ie One in the middle of winter and the other in the middle of summer.

Just ouf of curiosity -- can you show us the pictures? I have a feeling it'll look awesome as a wallpaper..

Jeschke in Linux Journal April 2003 using Layer Masks and adding Filters, however either I am doing something really silly or this does not work in Gimp 1.3.20.

Layer masks are what you need indeed. If I understand what you want correctly, this is what you should do:

Add a layer mask to the top layer (right-click; add layer mask)

Click the layer mask preview (next to the layer preview) to make sure it's selected. For some unholy reason the border that shows it's selected is white here, but it's there.

Select the gradient tool, and proceed to make a black to white gradient.

Because the layer mask was selected, instead of a black/white gradient you'll see the layer become transparent where the layer mask is black, and translucent where it's gray. The white area will be opaque.

Once again, this is my interpretation of what you want to achieve. I could be All Wrong.

Marco Wessel