<p>In this talk, I summarize the results from a series of investigations that are based on fundamental physics and are constrained by major solar observations to understand the dominant processes from the solar photosphere to the earth’s orbit. The chromosphere is a weakly ionized gas where Alfvenic perturbations from the photosphere is damped by plasma-neutral particle collisions. The energy that the neutral particles obtained from these inelastic collisions is radiated away to form the observed chromospheric radiation spectra. Because radiation function is steep in the range of a few thousand degrees, the chromosphere is roughly isothermal. The transition region is where the gas changes from weakly to fully ionized through ionization and recombination, in a process similar to evaporation/condensation at the surface of water which maintains sharp changes in density and temperature across the transition. At the top of the transition region, a continuous upward fully ionized flux is formed. Heat sources in the corona, mostly converting magnetic energy to thermal energy, are required to produce continuous solar winds. Since the upward flux is determined by the ionization/recombination processes at the transition region and heating processes in the corona, the solar wind speed and temperature generally do not satisfy the critical condition at the sonic point. A discontinuity or very thin sonic layer with increased temperature and speed may form at the sonic transition to reach the critical condition under various upstream conditions. Parker's solution corresponds to the condition that separates the supersonic from subsonic solar wind and is not the condition for forming all supersonic winds.</p>
