Sympathetic nervous system is activated in this situation.
This branch of nervous system is activated when any individual encounters stressful or dangerous situation.This is responsible for 'fight or flight' response.
It takes place by activating adrenal gland which releases specific hormones adrenaline and nor adrenaline also called as catecholamines . These hormones are responsible for the appropriate physiological response to the situation.
Water is warmed by the sun and is evaporated. It is then cooled down and condensed. Finally, it is brought back to Earth in the form of water droplets (Rain)
I hope it helps!^^ May the power of unicorns be with you!