Answer:
Nitrogen cycle
Explanation:
Nitrogen fixation is the process by which atmospheric nitrogen is converted by either a natural or an industrial means to a form of nitrogen such as ammonia. In nature, most nitrogen is harvested from the atmosphere by microorganisms to form ammonia, nitrites, and nitrates that can be used by plants.
Answer:
water is evaporated into the air then the water molecules get too heavy and come back down as snow/rain/ect
The burning of fossil fuels can cause smog and acid rain.
