马鞍山市2014高考英语阅读理解、动词短语精讲讲练（31）及答案
We experience different forms of the Sun’s energy every day. We can see its light and feel its wa rmth. The Sun is the major source of energy for our planet. It causes the evaporation (蒸发) of water from the oceans and lakes. Sunlight also provides the energy used by green plants to make their own food. These green plants then provide food for all organisms (生物) on the Earth.
Much of the energy that comes from the Sun never reaches the Earth’s surface. It is either reflected or absorbed by the gases in the upper atmospher e. Of the energy that reaches the lower atmosphere, 30% is reflected by clouds or the Earth’s surface. The remaining 70% warms the surface of the planet, causes water to evaporate, and provides energy for the water cycle and weather. Only a tiny part, approximately 0.023%, is actually used by green plants to produce food.
Many gases found in the atmosphere actually reflect heat energy escaping from the Earth’s surface back to the Earth. These gases act like the glass of a greenhouse in that they allow energy from the Sun to enter but
