Water vapor, dust, and ozone absorb around 23% of incoming solar energy, while the remaining 48% passes through the atmosphere and is absorbed by the earth. As a result, the Earth's system absorbs around 71% of all incoming solar energy. The remaining 48% is absorbed on the surface. Oceans absorb about 9% of this total solar absorption while land surfaces absorb about 39%. Clouds reflect around 30% of incident light but play an important role in regulating the temperature of the planet by acting as heat reservoirs or mirrors that can either trap sunlight during times of cloud cover or release stored heat when it rains or snows.
Incoming solar radiation is classified according to wavelength: long-wave radiation (IR), which accounts for 99% of all incoming radiation; and short-wave radiation (UV), which accounts for 1%. Of the short-wave radiation, almost all reaches the ground as visible light. The remainder is absorbed by the earth's atmosphere and surface materials.
At the top of the atmosphere, most of the IR radiation is radiated away by water vapor. Only around 0.5% of the incident IR radiation makes it all the way down to the surface. The rest is reflected back up towards space. On planets with atmospheres, such as Earth, some of this reflected radiation returns to the surface. On other planets, such as Mars, all of this returned radiation escapes into space.
Insolation is the term used to describe incoming sun radiation. Seventy percent of solar energy is absorbed by the Earth. The Earth's surface absorbs 51% of the solar radiation. Water vapor and dust absorb 16% of total energy. Carbon dioxide, ozone, clouds, and snow/ice reflect or scatter back some of the energy.
Of the remaining 29%, about 5% is reflected back into space and 24% is absorbed by the atmosphere. Of that, about 50% is absorbed over land, with the rest absorbed by oceans.
The average global annual energy balance (the difference between sunlight received at the surface and radiated back into space) is 1350 watts per square meter (W/m2). About 10% of this energy goes into melting ice and water, which causes ocean waters to heat up and glaciers and ice caps to melt. The remaining 90% is absorbed by the surface itself. Most of it is absorbed by vegetation, but a small fraction is absorbed by bare soil.
Solar radiation is classified according to wavelength: long-wave radiation (IR), medium-wave radiation (MW), and short-wave radiation (UV). Long-wave radiation accounts for only 4% of solar radiation but contains most of the energy because it can travel great distances through air, earth, and other materials.
Three-thirds Solar energy that reaches the outer atmosphere can have a number of outcomes. Solar energy is lost to space at a rate of 30% due to dispersion and reflection off clouds and the earth's surface. Another 19 percent is absorbed by atmospheric gases and clouds. The remaining 51 percent reaches the surface.
The amount of solar energy that reaches Earth's oceans is equal to the amount that reaches the land masses. About 71 percent of this energy is reflected back into space, while 29 percent is absorbed by the ocean surface and subsequently reradiated into space.
Solar radiation levels on Mars are about 1/10th those on Earth because the Red Planet has less than 1/100th the distance from the Sun. Therefore, it would take its Martian colonies much longer to develop technologies based on solar energy than it did for us to develop tools for harvesting solar power.
In conclusion, three-thirds of the solar radiation that reaches Earth's atmosphere is lost to space.
Because the Earth's atmosphere and surface absorb 71 percent of incoming solar radiation, they must radiate that much energy back into space in order for the planet's average temperature to stay steady. The atmosphere absorbs 23% of incoming sunlight, leaving the surface to absorb the remaining 48%. Of this amount, over half is taken up by clouds and water vapor with only a small fraction (7%) going into thermal radiation from the earth's surface.
Radiation heat transfer through air is mainly due to collisions between molecules of air. When an atom or molecule moves toward another molecule, they exchange momentum and leave with their original velocities slightly changed. This is called "bouncing off" or "elastic collision". Elastic means constant energy and momentum are conserved in each collision. In other words, if one measures the velocity of either particle before and after the collision, then it will be the same after as before. Only when a particle hits a rigid object does all its energy go into it, without any change in velocity (inertial mass).
The more massive an object is, the more energy it can store during elastic collisions. That's why objects made of heavy elements such as gold or silver will keep their heat longer than objects composed of light elements such as hydrogen or helium.