Fusion - How to create a vertical gradient for Waviness strength

[Robbbb]

Hi everyone,

I'm trying to create a smoke-like distortion effect in Fusion using the Waviness node.
What I’m aiming for is a vertical gradient in the strength of the effect:

• At the bottom of the rectangle → no waviness
• At the top → strong waviness

So the distortion gradually increases from bottom to top,
At the moment, the Waviness node applies the effect uniformly across the whole image, and I’m not sure what the best approach is to control its intensity based on position.