Research shows that cosmic rays entering the thundercloud cause the air in the thundercloud to ionize, which in turn generates many suspended free electrons. The electric field already in the cloud layer causes the free electrons to carry higher energy. When the existing electrons in the air collide with water molecules, more electrons are released. Researchers call it a high-energy snow storm, which eventually results in an "escape". This discharge process is what people think Of lightning. The following statements are inconsistent with the original:. ['Lightning due to cosmic rays.', 'Lightning from snow storm discharge.', 'Lightning due to clouds colliding.', 'Lightning caused by collision of electrons with water molecules.']