Your body is responding to the immense heat of the sun and your body emits sweat from your body of the effort to cool your body down so that you don't get too hot
The geological conditions.
Answer: irregular,inconsistent, unsteady, uneven, shaky, fitful, patchy, variable, varying, changeable, changing, ever-changing, on-and-off, off-and-on, inconstant, erratic, haphazard, unstable, unsettled, spasmodic, sporadic, episodic, intermittent, occasional, unpunctual, wavering, fluctuating, aperiodic, unsystematic, unmethodical, ...