Rotating Skybox help

There is any way to change the direction in which way the skybox is spinning? I used the bellow code to make it spin (rotate), but i can’t find a way to change his direction…

float rot;

void Update() {

rot += 10 * Time.deltaTime;
rot %= 360;

RenderSettings.skybox.SetFloat(“_Rotation”,rot);

}

rot -= ?