Mesh Fireball - world mapped

Here's a world mapped fireball, just using a sphere mesh that's been stretched, tapered and then bumped up with noise. It has vertex colours (alpha) painted in a gradient from one side of the sphere to the other to control the taper/stretching area.

Instead of using 2 meshes for the layers of fire, it might be possible (better?) to do it with an outline in the shader - just to keep it down to one object.