Electrodynamics of the ionosphere

We review various important studies in the field of electrodynamics of the ionosphere. Four topics are presented; (1) conductivity, (2) wind and the dynamo theory, (3) drift and its effect on the ionosphere formation and (4) interaction between wind and electromagnetic field.We point out some important future problems. They are: (1) We need to consider in the dynamo theory of the geomagnetic daily variation the connection of the ionosphere of both hemispheres by lines of force of the geomagnetic field. (2) Non-periodic wind may be important for producing electric field. (3) Drift to cause interchange of ionization contained in tubes of the geomagnetic field lines, and diffusion of ionization in these tubes control dynamic behaviours of the F2 region. (4) Interaction between wind and electric current presents a new problem. (5) The ionosphere and the magnetosphere react to each other.