Short wave photons, so called "extreme UV" (XUV) lying between UV and x-rays, are extremely strongly absorbed by air molecules. These photons are emitted by the solar corona, and the emission is strongly dependent on solar activity, which pumps energy into the corona. Solar flares emit large bursts of XUV.
Being very strongly absorbed by air molecules, they deposit their energy in the thin upper fringes of the atmosphere, creating the so-called thermosphere, where temperature can become very high (2000 C). The scale height of an atmosphere increases with temperature, so this upper layer puffs outward when it is heated.
Short wave photons, so called "extreme UV" (XUV) lying between UV and x-rays, are extremely strongly absorbed by air molecules. These photons are emitted by the solar corona, and the emission is strongly dependent on solar activity, which pumps energy into the corona. Solar flares emit large bursts of XUV.
Being very strongly absorbed by air molecules, they deposit their energy in the thin upper fringes of the atmosphere, creating the so-called thermosphere, where temperature can become very high (2000 C). The scale height of an atmosphere increases with temperature, so this upper layer puffs outward when it is heated.