| A | B |
| evaporation | the slow changing of a liquid into a gas |
| condensation | the changing of a gas into a liquid |
| precipitation | any form of water particles that falls from the atmosphere and reaches the ground |
| water cycle | the continuous movement of water between Earth's surface and the air, changing from liquid to gas to liquid |
| carbon cycle | the continuous exchange of carbon dioxide and oxygen among living things |
| nitrogen cycle | the continuous trapping of nitrogen gas into compounds in the soil and its return to the air |