The typical meaning of negative ion refers to negatively charged air or any particles that electrons are attached. If a particle has an extra electron, it is called a negative ion while if it lacks an electron, it is a positive ion. In nature, negative ions are generally produced by radioactive rays in the atmosphere, photosynthesis of plants, or the cohesion and dispersion of moisture, which is related to the formation of rain. Therefore negative ions are present near the source of high voltage electric current, plants, waterfalls and streams where the water breaks into foam, and in the atmosphere, and after rainfall.
In some cases, negative ions are produced by rock salt, tourmaline, and radioactive minerals, but the amount is too little for actual use.
- Radioactive materials radiate diverse rays, including alpha, beta, and gamma rays, and beta rays are negative ions, free electrons.
- Negative ions are generated when gamma rays hit the air.
- Also X-rays and radio waves charge the air and produce both positive and negative ions.
- In waterfalls, when the water falls on rock and breaks into foam, many negative ions are produced.
- Around electric power transmission lines and high voltage equipment, both negative and positive ions are generated.
- CRTs in TVs and computer monitors generate positive ions mostly.
- Right before rainfall, the atmosphere is charged positive and many positive ions are produced. However, after rainfall, a lot of negative ions are produced. Especially when lightning strikes, a massive amount of both negative and positive ions are produced.
- Some kinds of salt rock and radioactive elements present in earth produce a small amount of negative ions.
- Tourmaline's structure makes it to produce negative ions from one side when water is absorbed to the other side, and to absorb negative ions when the water is removed. When mixture of zeolites, or active carbon, and tourmaline is shaken, it produces some negative ions. This happens because zeolites and active carbon are strong adsorbents of water so they provide moisture to tourmaline, and it turn tourmaline may produce negative ions, but this is thought to be a momentary phenomenon.
- Beside these, some special stone and jewels release a small amount of negative ions, too. The reason is thought to be same as described above: the activity of radioactive materials and the absorption of water by tourmaline.
- Static in dry climate may be another cause to produce both negative and positive ions.
- In the production of fabric and clothes, negative ions are generated.
- So is in the production of plastic and paper.
- Most plants make necessary organic compounds through photosynthesis, and in the process they release moisture and absorb carbon dioxide, at the same time negative ions are released, too. People feel good and fresh in forests, and phytoncides and negative ions are known to be the major players. Some plants produce negative ions more than others, even twice more.
- Both negative and positive ions may be present in the eruption cloud of volcanoes. Lightning is often observed in the the eruption cloud.
- Ions in the atmosphere are something that antenna installers have to take heed of. One may experience an electric shock right before rain, and this is because of the presence of ions.