This seminar introduces the climatology, anomalies, turbulence, and storm-time disturbances in the Earth’s ionosphere. Many ionospheric phenomena are associated with the variation of ionospheric height and atmospheric composition. Plasma density is sensitive to those factors because the plasma loss rate is sensitive to the molecular gas (O2 and N2) number density which varies with height. Atmospheric winds induce electric fields and plasma motion along the magnetic field lines by which the ionospheric height varies. Neutral composition is variable with season and hemisphere owing to the variation of the solar zenith angle and the Sun-Earth distance. During geomagnetic storms, the solar wind and magnetospheric energy deposition into the polar atmosphere causes an expansion of atmosphere, and the increase of molecular gases in the ionosphere induces plasma depletion in high latitudes. In low and middle latitudes, the plasma density either increases or decreases by the effects of storm-induced winds and electric fields. The goal of this seminar is to help an understanding of the plasma-neutral interaction and its effect on the ionosphere.