Click on the masking icon, and mask the top off using a soft black Brush.
Reset the color palette (D), and create a new layer as “right-rays”.
Fill in White, and then go to Filter > Render > Fibers. Apply these settings – Variance: 15; Strength: 4.
Next, go to Filter > Blur > Gaussian Blur. Set Radius at 5 pixels.
Then, go to Filter > Blur > Motion Blur. Set Distance at 235 pixels.
Change Blend mode to “Screen”.
Transform this layer so effect fits the image’s perspective.
Adjust the levels.
Merge “right” and “right-rays” together. When merged, the Blend mode of the new layer will return to “Normal” resulting in the reappearance of the dark, black areas. Just set the Blend mode back to “Screen”.
Draw a rough selection on how you envisioned the aurora’s shape, feather it…
… and mask it away.
Moving on to “middle”.
Apply Filter > Blur > Motion Blur. Here are my Motion Blur settings…
When complete, duplicate the layer a few times and merge them together for increased opacity.
Mask off the excessive areas. Try to mold it into similar shape, as below:
For “left”, I applied the methods similar to “right, but created larger gaps on my Filter layer (see below steps 3 to 5). Once I’ve merged my “left” and “left-rays” layers, I further tweaked my settings at “Levels” for a softer look (see step 6).
Once done, we can merge all 3 layers “left”, “middle”, and “right” together. Rename it as “aurora”. Again, set the Blend mode back to “Screen”.
Next up, applying colors to the aurora.
Create a new layer as “color”. Using a soft Brush, draw streams of lines like this:
Next, apply Filter > Blur > Gaussian Blur.
Then, change its Blend mode to “Overlay”, and set opacity to 80%.
Create reflections on the lake.
Duplicate “aurora”, flip it, and give it a little perspective. Set opacity to 40%.
Duplicate “color”, flip it. Erase those areas that touched the mountains. Set opacity to 65%.
We can further reduce the brightness and introduce some more blue to the image:
In my final image, I’ve altered the contrasts and hues of the image, and strengthened the shine of the stars. For an extra touch, I’ve added some clouds at the center to enhance the overall look and feel of the image.