Copy and paste skydome BP and cloud texture from UE source to our content and make some changes on the mappings.

sky texture

In order to create our own stylized sky texture, I first use 6144*2048 resolution canvas with alpha channel, paint and loop around it. The final image should be scaled down to 2048*2048.

In photoshop we can use offset to create seamless looping texture.

cloud texture

For the cloud I use 2048*1024 pixels texture. This is a black and white maskout texture.

We can add more cloud layers to make a more dynamic movement.