The Earth upper atmosphere is a strongly forced and coupled system. Because the major external energy sources are the solar radiation in the range of extreme ultraviolet (EUV) and far ultraviolet (FUV), and the solar wind energy, a flow of charged particles (plasma) from the sun, the state of the upper atmosphere depends strongly on the solar activity. When the solar activity is high, magnetic storms occur as a results of increased magnetospheric energy inflow, mainly in the form of electric fields and auroral plasma particle precipitation. During magnetic storms, the energy is transferred from the magnetosphere to the polar atmosphere and distributed among kinetic, internal, and chemical energy of the thermosphere and ionosphere via a number of neutral-plasma interactions. During geomagnetically disturbed periods the ensuing high-latitude ionization, Joule heating, and ion-drag forcing of the upper atmosphere, along with penetration of the electric fields to low latitudes, affect the global dynamics and structure of the thermosphere and ionosphere, and can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health. Thus, as the nearest space environment to us, it is important to understand the Earth\\\\\\\\/s upper atmosphere. In this study, the physical processes responsible for maintaining the coupled thermosphere-ionosphere\\\\\\\\/s dynamical system with respect with the solar activity will be presented.<br /><br /><br /><br />