(I) On average, 30% of the solar radiation that falls on Earth is immediately reflected away by clouds and surfaces, especially snow, ice, and ocean. (II) Trees of tropical rain forests are usually evergreen flowering plants. (III) The remaining 70% is absorbed by Earth and runs the water cycle, drives winds and ocean currents, powers photosynthesis, and warms the planet. (IV) Ultimately, however, all of this energy is lost by the continual radiation of long-wave infrared energy into space. (V) In fact, if heat gains from solar radiation were not balanced by losses, the Earth would heat up or cool down.