We draw a rainbow on the photo

Create a new layer (click on the panel Layers )

Name this layer Rainbow.

Select gradient tool (Gradient tool) on the toolbar

Let’s compare the settings before proceeding.

Make sure is selected Linear gradient.

Press once on the button marked with the letter BUT and open the gradient selection window.

Choose gradient “transparent rainbow” marked beech B and click on the button A second time to close the window.

Attention: If you do not find a gradient in your window, then you need to click on the button marked with the letter C and in the window that opens, select Reset gradients – noted (D) and when the next window opens, asking whether to add selected gradients, you just click OK.

We continue to check the settings, look at this screenshot:

Now hold down shift (this will help to draw a rainbow at right angles), click somewhere in the center of the screen and move the cursor down a small distance (1-2 cm) – it will be the diameter of the rainbow, click again and release the key shift:

Now select from the menu Filter / Distort / Polar Coordinates …

Select Rectangular to polar and press Ok:

As you can see, the gradient took the shape of an ellipse. If your document had the shape of a square, then the rainbow would be round. You will find out that this is actually not so important.

Caution: The outer ring of the rainbow should be red – This is a natural phenomenon.

Zoom out on 30-35%, so that the gray area surrounding the document becomes visible.

Click Ctrl + t to activate the team free transformation.

Move the rainbow to the right corner and pull the lower right corner of the transformation frame to change the proportions and size of the rainbow until you get something like this:

Click Enter, to fix the transformation.

Return 100% double click image size
Zoom tool (at the bottom of the toolbar).

In the menu, select Filter / Blur / Gaussian Blur … and enter the radius 4.5 px or less and click Ok:

Change blending mode this layer on Screen and reduce the transparency to 80%:

To add a layer mask, click on the icon. Add layer mask the icon is at the bottom of the palette Layers.

Select Brush tool from the tools and take a soft round brush and set the following settings:

Make sure that the main color is black and that the mask is active (it will have a double border) and draw in the bottom left of the rainbow to move it:

Now we are going to add the illusion of tiny water droplets inside the rainbow.

Add a new layer by clicking the window. Create a new layer and rename it to Water Drops (water droplets).

Press a letter D, To set the main layer as black and the background layer as white.
Press a letter X to switch colors. Now the main color is white.

Now use the brush that you used before (transparency Opacity must stand 100%) and paint the rainbow inside, look at the picture below. Do not paint very close to the rainbow and do not paint the trees on the right, as we want to achieve the illusion of depth:

The last thing to do is change opacity (transparency) layer to 15%:

Final result:

The effect will look much better if you take the right photo – for example, a photo with a perfect blue sky without clouds and in the daytime is not very suitable.
You can experiment with the gradient diameter settings for the rainbow and the blur parameter. Usually, the lower the blur level, the tighter the colors look.