Step 1 - New Document
Ok lets get started! First of all we need to create a new Photoshop document, so “File > New” from the menu bar, and I’m going to be using a canvas of 640 pixels wide by 300 pixels high. You can choose a different height but it’s probably easier to work out small first to you can get the detail right.
Step 1 - Making the selection
Ok, so now we have a new canvas set up, we are going to make the basic shape of our cloud. First of all we need to create a new layer, so from the top menu click ” Layer > New > Layer” and I am going to rename this layer ” Clouds “.
Next we are going to select the “Lasso Tool” from the toolbar,which looks like this : 
Now we are going to simply create a cloud shaped selection using the Lasso tool on our canvas. Here is the shape I made :
Step 3 - Making the clouds
As you have created your new layer, and you have an active selection on the screen, hit “D” on your keyboard to reset the color palette to a black foreground color and a white background. This will ensure that we won’t have strange colored clouds, unless you want to of course! The from the menu, go to “Filter > Render > Clouds”, and you should end up with something like this :
Now we want to duplicate this layer, so from the menu, ” Layer > Duplicate Layer” and rename this layer ” Clouds Overlay”. We want to change the blending mode to ” Hard Light “, so if you navigate to the layers panel and click on the duplicated Clouds layer, there will be an option at the top of the panel selected on Normal. Click this and change to ” Hard Light”. You should end up with something like this :
Step 4 - Adding the gradient
As you can see, our cloud is looking at bit weird with the surrounding white. So we are going to quickly add a blue gradient to the background layer, so you need to click ” Background ” on the layers panel, then from the tools bar, then click the gradient button ( Labeled 1 below ). Ensure you have a decent foreground and background color palette ( Label 2 ) - I’ve used two blues for a sky type background. Then, click and drag your cursor to make a straight gradient, ( Labeled 3 ).
And you should end up with something similar to this :
Step 5 - Creating the rain
Ok this is really simple, all we are going to do is make a new brush. So we are going to make a new document ( File > New ) but don’t close the clouds file we have been working on. I suggest using the same size you did before for the clouds file.
We are going to select a soft round small brush from the brushes menu ( to get to the brushes palette, click the brush tool or hit “B” on the keyboard and from the tool menu click the arrow next to the selected brush, this is illustrated below ).
Let’s reset out color palette to black and white, so hit ” D” on your keyboard. And all we want to do now is create a new layer and click once in the center of our canvas to create a little black dot. ( Labeled 1 below ). Then we want to duplicate this layer ( Layer > Duplicate Layer ).
We now have two layers containing the dot, select the lower layer from the layers panel, then from the top menu click ‘ Filter > Blur > Motion Blur ‘ change the angle to 90 degrees and the distance will define how long your raindrop will be ( I’ve chosen 19 for this example - refer to label 2 below ).
We now want to select the Move Tool, ( The highest icon on the toolbar, or tap ‘V’ on your keyboard ), and just move our blurred rain above the rain dot, labeled in step 3.
Step 6 - Creating a dynamic brush for the rain
Now we have our single drop of rain, select it using the ‘Rectangular Marquee Tool” Hit ‘M’ on your keyboard, and just click down on the canvas and drag to select an area around your drop. We now need to make this into a brush, so click from the menu bar ” Edit > Define Brush Preset” A diag box will pop up, just hit ok.
Now select this newly created brush from the brushes palette ( Check back to step 5 if you can’t remember how ), and your new brush will be the last brush on the list.
When you have selected your brush, you need to open the brushes panel, so from the top menu, ” Window > Brushes “. When this is opened, I am going to change the parameters for the rain brush, i’m going to click ” Scattering ” option, and change the scattering to 1000%.
Step 7 - Adding the rain
We need to open back up the clouds file, and create a new layer ( Layer > New Layer ) and our rain brush is already selected, so change the foreground color to white in the tools panel. All we need to do now is paint on the rain below our clouds! If you like we can erase the top section of the rain using the erase tool ( Hit ‘E’ on the keyboard ) to create a smooth flow!
Here is my finished product!
