Answer
$(-Z_x, -Z_y, 1)$
Work Step by Step
Let $Z$ denotes the orientation of a surface of a sphere and is given as: $Z=g(x,y)$
Here, $g(x, y)$ defines the continuous and differentiable function.
Next, the normal vector for the given sphere can be expressed as:
$(-Z_x, -Z_y, 1)$ in the upward direction.
