Full context:   Solar radiation (or sunlight) is the energy Earth receives from the Sun. Earth also emits radiation back into space, but at longer wavelengths that humans cannot see. As energy propagates through the atmosphere, it is impacted by the process of radiative transfer. That is, some of the incoming and emitted radiation is subject to absorption, emission, and scattering by the atmosphere. Another portion of the incident energy is reflected, with the two most important atmospheric reflectors being dust and clouds. Depending on the properties of the aerosol, clouds can reflect up to 70% of the incident radiation. Globally, clouds reflect 20% of the incoming energy, contributing two thirds of the planet's total albedo. In May 2017, glints of light, seen as twinkling from an orbiting satellite a million miles away, were found to be reflected light from ice crystals in the troposphere.