Bukkit

There are many settings that are available in the configuration
This should aid you in determining which settings best suit your requirements

globalEnabled

(Boolean, true)

If true, then is automatically enabled on any normal-environment world
(not end or nether)

enabledWorlds

(String, Comma-delimited list)

if globalEnabled: false, then these are the world names to allow generating clouds on

softClouds

(Boolean, false)

if true, any fall damage caused by falling onto a cloud (within the cloud layer) is canceled

minCloudHeight

(Integer, 6)

This is the minumum distance from the ground that a cloud must be in order to be generated
(Trees and buildings do not count ad part of the ground. However, should a cloud interfere with any other block, the cloud is canceled)

maxCloudDepth

(Integer, 3)

The maximum thickness of a cloud

cloudFloor

(Integer, 80)

This is the y-value where clouds begin to generate
Setting this below the average ground height will result in far fewer clouds, as the ones below the ground will not get generated

cloudCeiling

(Integer, 200)

This is the top-most y-value of any generated cloud

noiseScale

(Float, 1/19)

This is involved in the generator algorithm
In general, smaller values cause larger clouds

noiseOctaves

(Integer, 6)

This is involved in the generator algorithm
Lower numbers seem to cause 'blobbier' clouds

noisefreq

(Float, 0.4)

This is involved in the generator algorithm
Higher values can cause additional roughness on the generated clouds

noiseamp

(Float, 0.3)

This is involved in the generator algorithm
Higher values result in fewer clouds, lower values cause more

yScale

(Float, 2.1)

This is involved in the generator algorithm, and linked to the cloud depth texture
lower values can make taller, less changing clouds
higher values can make disjointed-looking structures

noisethreshold

(Float, 0.6)

This is involved in the generator algorithm, linked to the distribution and size of the clouds
values range from about -0.9 to 0.9
lower values cause more and larger clouds
higher values less and smaller

min_cloud_size

(Integer, 5)

Once a cloud structure has been identified by the generator, this is the first test it goes through before being placed
any cloud containing fewer than this number of blocks will not be generated

max_cloud_size

(Integer, -1)

Maximum size of a cloud allowed to be generated
-1 indicates no limit

block_id

(Integer, 80)

What block the clouds should be made of

block_data

(Integer, 0)

If you're using a block with a data aspect (like wool or stained clay), you can set that value here