ocr: SUN-EARTH CONNECTION VARIATIONS IN THE UV AND EUV EMISSION The UV/EUV irradiance is the major energy source for the Earth's atmosphere and the variations cause changes in the photochemis- try, dynamics, and the energy balance of the atmosphere and plays an important role in the formation and destruction of ozone. The variations in the short wavelength (UV and EUV) solar spectral irradiance are much larger than in the total solar irradiance. In X rays the variations over a solar cycle can be upto a factor of 20. How the changes in the upper atmosphere can affect the thermo- sphere is yet unknow ...
