Creating a Fluffy Cloud

Question

I am trying to create a cloud like this

(taken from Is there an easy way to make volumetric clouds for Cycles?)

The closest I am able to get is

I have taken these steps:

• Switch to Blender Render
• Turn on cloud generator addon (file --> user preferences --> add-ons --> search{cloud})
• scale default cube on x-axis by 2 (sx2enter)
• go to create tab on left
• scroll down to cloud generator and expand
• change type to "cumulous" [sic]
• click generate cloud
• switch to cycles render
• expand cloud bounds on outliner
• delete "CloudMesh" and "DefinitioinObj" [sic]
• remove unnamed material from CloudBounds
• click on CloudMaterial
• go to node editor (shiftF3)
• tick "use nodes"
• delete diffuse node
• add nodes as in

(taken from Is there an easy way to make volumetric clouds for Cycles? as well)

• add sun lamp (strength 3, ~7 units away from CloudPoints)
• add hemi lamp (also ~7 units away from CloudPoints)
• change Light Path --> Volume --> 5 bounces max (from 0)
• change number of samples to 100
• render (F12)

How can I make my cloud more white and fluffy? (the color in volume scatter is already white - changed from 0.8 to 1.0 alpha)

File Rendered at 25% of 1920 x 1080 with 100 samples:

Answer 1

Here's what your file looks like rendered with the Sun lamp strength set to 4 (it was set to 1):

The key to having a good "fluff" is a wide dynamic range. Dynamic range is the distance between the brightest and darkest parts of an image. See Render with a wider dynamic range in cycles to produce photorealistic looking images for a good introduction to a whole rabbit hole of lighting, grading, and generally managing the dynamic range of your scene and image.

The simple answer

For the simple answer, suffice it to say that the sun is bright. By making the sun lamp significantly brighter than other light sources, you'll start to get an increased dynamic range and clouds will take on more of a "fluffy" look (bright highlight falling off to shadow) when seen from the side.

By using a bright sun lamp and messing with camera settings (exposure, contrast etc.) to get the final image to have the overall brightness you want, you can get a decent physically-based-ish result without too much fuss.

The proper answer

We know that the sun lamp energy in Blender is measured in terms of irradiance, or the amount of energy (light) from the source hitting another object at a given point in time (the exact units are Watts / meters²).

The Sun's irradiance measured on Earth varies over a whole host of things, not least of which is how much atmosphere the sunlight must go through. Assuming we are simulating light scattered by the atmosphere separately (e.g. with an emissive sky texture), we'll want to make the sun strength something like 1050 W/m². If instead we are sparing no expense and simulating the atmosphere with a large volumetrically scattering object, we'll want to include atmospherically scattered light in the sun lamp and make it more like 1361 W/m² (taking values from Wikipedia).

If this seems insanely bright, that's because it is (have I mentioned the Sun is bright?). By using Sun lamp values around the default of 1, we're putting our Blender scenes over 4,300,000,000 km farther away from the Sun than the Earth (somewhere beyond Neptune)!

Here's an example with a 1050 W/m² Sun lamp, a 300 W/m² sky, and a camera exposure of -7 (with filmic):