Atmospheric insolation

Nature-induced RF for the last century due to SC changes (including an indirect impact on the ozone layer) can be assumed to be 0.4 0.2Wm"2. Since total RF constitutes only about 1W m 2, the contribution of variations in extra-atmospheric insolation could play a substantial role. 

Many uncertainties also remain about the impact of present changes in extra-atmospheric insolation on climate. Soon et al. (2000) detected, for instance, the super-sensitivity of the climate system to changes in UV insolation whose impact is enhanced by the feedback due to the statistical stability of clouds, influence of tropical cirrus clouds, and stratospheric ozone (the ozone-climate problem needs special analysis) (Kondratyev and Varotsos, 2000). 

The change in extra-atmospheric solar radiation is a climate-forming factor that should be considered. The contribution of such a change to RF since 1750 might be as much as 20% compared with the contribution of C02. This is mainly explained by enhanced extra-atmospheric insolation in the second half of the 20th century (consideration of the 11-year cycle of insolation is vital here). However, the mechanisms that underly the impact of solar activity on climate are still far from being understood. Nonetheless, IPCC (2007) contains some conclusions and estimates. 

The solar radiation incident on a unit horizontal surface at the top of the atmosphere. It is sometimes referred to as solar irradiance. The latitudinal variation of insolation supplies the energy for the general circulation of the atmosphere. Insolation depends on the angle of incidence of the solar beam and on the solar constant, instantaneous transpiration efficiency... 

Table 21. Insolation at Various Latitudes for Clear Atmospheres ...

For some high growth-rate biomass species, the carbon dioxide concentration in the air among the leaves of the plant often is considerably less than that in the surrounding atmosphere. Photosynthesis may be limited by the carbon dioxide concentrations under these conditions when wind velocities are low and insolation is high. 

Berger, A. L. 1978. Long-term variations of daily insolation and quaternary climate changes. J. Atmospheric Sci. 35, 2362-67. 

TABLE 23-24 Typical Atmospheric Stability Classes in Terms of Wind Speed, Insolation, and State of the Sky... 

The global heat cycle drives the hydrological cycle, which in turn controls the salinity of seawater. The most important contributor of heat to the crustal-ocean-fectory is solar radiation. The flux of solar radiation that reaches Earth is termed insolation. Only a fraction of the incoming solar radiation reaches Earth s surfece, because a large portion is either reflected or absorbed by the atmosphere. That which reaches Earth s surface is also either reflected or absorbed. In the end, about half of the incoming radiation is absorbed by the rocks and water on Earth s surfece. (A detailed heat budget is provided... 

The latitudinal heat gradient in the atmosphere and ocean remains relatively constant over time despite the short-term and spatial variations in insolation. This steady state is maintained by the net transport of heat from low to high latitudes where it is radiated back into space. Atmospheric currents (winds) are responsible for about half of this meridional net transport of heat. The rest is accomplished by water movement in the... 

Greenhouse effect The warming of Earth s atmosphere as a result of the retention of solar radiation. This retention is possible because insolation absorbed by the land and ocean is radiated back to the atmosphere as IR energy. This energy is absorbed by atmospheric gases and then radiated from them as heat. 

Fig, I, Availability of solar eueigy (insolation) (a) Average number of horn s of sunshine per year (United States) (b) median daily insolation in langleys (North America in June) (c) in December. (National Oceanic and Atmospheric Administration)... 

One year later, during May 1997, another similar but less extensive campaign took place in Bavaria, Germany in order to obtain data from a different insolation and composition atmospheric regime. 

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