Water cycle can begin were you want. It normaly begins with evaporation wen the water turn from liquid to gas. Condensation is the turn of gas to any precipitation depending on the temperature, it can be hail, rain, snow, sleet, due, ect. Presipitation is the tuning of liquid to gas to liquid that falls from the clouds.
Carbon dioxide enters the air when plants and animals decay. It enters the air when animals breath out. It enters the air when fossil fuels such as coal, oil, gasoline, and natural gas are burned. Forest fires also ad carbon dioxide to the air.
Air is made up of 78 percent of nitrogen gas. some bacteria that grow on pea and bean root give those plants the nitrogen they need. Plants absorb nitrates disolved in water throug their root. The nitrogen is then used by the plants to make proteins