Earth's main energy source is from the sun, about 1.3x10²⁴ card each year. Figure 2-5 shows that the spectrum of solar radiation is getting weaker when it through the atmosphere. Curve 1 is the upper bound of atmospheric solar radiation spectrum; Curve 2 is the ozone layer under solar radiation spectrum; Curve 3 is taking into account the molecular scattering spectra; Curve 4 is the spectral after further consideration of the color of coarse scattered; Curve 5 is the spectrum of water vapor absorption  taken into account; It can also be approximated as the observed surface solar radiation spectrum.
Composition of the atmosphere absorbs solar radiation are mainly water vapor, oxygen, ozone, carbon dioxide and solid impurities. Water vapor in the visible and infrared regions have a lot of absorption bands, absorption of infrared region is the strongest, the absorption band between 0.93-2.85 micron. Atmospheric water vapor can reduce about 4-15% solar radiation.

In terms of global average condition, approximately 31% of solar radiation reflected and scattered back into space, 24% is directly absorbed by the atmosphere, 45% reach the ground. The radiation wavelength focused between 3-120μ. Obviously, ground and atmospheric radiation wavelength are much longer than the solar radiation’s, So often referred to as short-wave radiation of the sun radiation. Longwave radiation is an important way of heat exchange between the ground and the atmosphere. It is very few that the Atmosphere absorb the solar radiation directly, It is mainly by absorbing longwave radiation gain heat. Atmospheric water vapor, carbon dioxide can strongly absorb long-wave radiation, which water vapor absorb long-wave radiation the most significant. the wavelength 4.5-80μ can be absorbed, nearby 6μand more than 25μ wavelength of them is absorbed the strongest, the weakest absorption is in the range of 8.5-12μ, but the ground radiation in this wavelength range has greater radioactivity, through the atmosphere, go to the universe, therefore, this range of radiation was called "Atmospheric window". From 18μ later, the absorption rate increased rapidly, almost been absorbed completely (see Figure 2-11).
    Solar radiation projected onto ground, is not completely been absorbed by the ground, some of which are reflected by the ground, ground surface reflective ratio of solar radiation, depends on the nature and status 
of the ground surface. Land surface reflectivity of solar radiation is about 10-30%, dark earth is smaller than the light-colored soil reflectance, rough soil is less than smooth soil reflectance, moist soil is less than dry soil reflectance, ocean reflectance is 20% smaller than the land.
Water is the best weapon to solve the radiant heat, plants will not solve the problem of radiation heat, plants absorbed moisture, discharged from the plant via evaporation holes, in order to reduce radiant heat. 
Water is the single best way to solve the radiant heat.