Cloud procedural texture can be found here:
A demo can be found here: https://www.babylonjs-playground.com/##NQDNM#0 -
This texture has 2 parameters :
Sample to create a cloudy sky
var boxCloud = BABYLON.Mesh.CreateSphere("boxCloud", 100, 1000, scene);
boxCloud.position = new BABYLON.Vector3(0, 0, 12);
var cloudMaterial = new BABYLON.StandardMaterial("cloudMat", scene);
var cloudProcText = new BABYLON.CloudProceduralTexture("cloud", 1024, scene);
cloudMaterial.emissiveTexture = cloudProcText;
cloudMaterial.backFaceCulling = false;
cloudMaterial.emissiveTexture.coordinatesMode = BABYLON.Texture.SKYBOX_MODE;
boxCloud.material = cloudMaterial;