Solar radiation
Approximately 30% of solar radiation dochodzącego the planet is reflected by the atmosphere. 20% is absorbed by it, and only 50% of the energy reaches the earth's surface.
Many fires in the hot regions of the Earth is caused by focusing sunlight in the morning dew. Already 400 years BC The Greeks used the sun's rays, concentrated in the glass sphere filled with water, the kindling fire. Chinese, 200 years BC have used curved mirrors to concentrate sunlight.
In modern microwave solar rays are focused to heat the food. Curved concentrator focuses sunlight on the product. Some of the ovens, instead of curved mirrors, using flat reflectors, positioned at a right angle.
A similar technique is used in industrial furnaces. The Mont Louis, France, multi-storey structure of small reflectors, arranged, creating a giant, curved mirror. The focus point is obtained the temperature to 3000 ° C - suitable for treatment of many metals.