Water travels to the clouds through evaporation. This is the process of the sun's heat turning the water into a gas. The water floats up to the clouds, where it begins Condensation. Condensation is when the vapor in the clouds reverts back to a liquid water. Clouds form because of condensation. Clouds are made of millions of tiny droplets of water, or crystals of ice. These form when the water vapor condenses on the particles of dust and other substances. Precipitation is the process where all the water gathered up in the cloud falls back down to the land. It can enter bodies of water, like lakes or oceans, and evaporate from there. Precipitation can come in different forms, like rain, snow, sleet, or hail. And after the water falls down into the earth, it evaporates again later, and the cycle continues.
Nitrogen in the air can go underground through the roots of a plant, which attracts Nitrogen-fixing bacteria in the plant roots. The bacteria in the soil turns the Nitrogen into a usable form of Nitrogen. Then, biotic factors eat the plants that contain Nitrogen, turning it into a protein. Decaying organic matter like animal waste return Nitrogen compounds to the soil when bacteria convert them to Nitrogen gas that travels back into the atmosphere, ready to be used in the cycle all over again.
Carbon dioxide in the air can be released from several sources. For example, death and decomposition can release the Carbon dioxide into the air. Respiration is another way. When animals and plants respire, sugar molecules are broken down to release energy. Carbon dioxide and water are released as byproducts. Combustion is when the coal, oil, or natural gas is burnt. The carbon is then released into the air. Carbon is also useful during photosynthesis, Photosynthesis is when plants use carbon dioxide from the air to make sugar. This is why animals get the carbon they need by eating the plants. Carbon dioxide can also enter and exit from fossil fuels.
During photosynthesis, plants release oxygen gas into the air. From there, animals and other organisms take in the oxygen gas from the air. Once that is done, the animals and the other organisms release carbon dioxide into the air. And during photosynthesis again, the plants take in the carbon dioxide to make sugars. The cycle repeats itself.