¥Atmospheric Composition - Anything that
changes the radiative
properties of the atmosphere (volcanic aerosols, carbon dioxide).
¥Astronomical - Anything that alters the
amount or distribution
of solar energy intercepted by the Earth (solar variations, orbital variations).
¥EarthÕs Surface - Anything that alters
the flow of energy at
the Earth's surface or changes its distribution (desertification, continental drift).