Solar radiation heat balance

Just as in the case for the hydrosphere, the atmosphere participates in all of the major biogeochemical cycles (except for phosphorus). In turn, the chemical composition of the atmosphere dictates its physical and optical properties, the latter being of great importance for the heat balance of Earth and its climate. Both major constituents (O2, H2O) and minor ones (CO2, sulfur, nitrogen, and other carbon compounds) are involved in mediating the amounts and characteristics of both incoming solar and outgoing infrared radiation. 

If this excess absorption by clouds is ultimately shown to be a real phenomenon, then an increased cloud formation and extent due to anthropogenic emissions may alter the radiative balance of the atmosphere not only through increased reflectance but also through increased absorption of solar radiation. Such an effect could impact atmospheric temperatures, their vertical distribution, and circulation, as well as surface wind speeds and the surface latent heat flux (Kiehl et al., 1995). Hence establishing if this is truly excess absorption, and if so, its origins, is a critical issue that remains to be resolved. 

Performance. So far, the deep-basin still has been operated only under batch-type control—that is, without continuous blowdown or heat exchange to the incoming sea water. In determining the performance of the still, incident solar radiation and distillate production are measured daily. From this information, the specific production in gallons per square foot per day and the thermal efficiency can be determined. In addition to the daily collection of performance data, hourly collections are made during periodic energy- and mass-balance runs. 

Analysis of these data showed that the heat balance cannot be closed an additional input of 20Wm-2 to the atmosphere is needed. Attempts to use different versions of input data bases were unable to remove this imbalance. Since water vapor balance could be closed using the same data, it seems that this imbalance is caused by inadequate estimates of the atmospheric radiation balance as a result of underestimation of calculated values of solar radiation absorbed by the atmosphere. 

Calculate the equilibrium temperature of each of the tank surfaces. It can be shown that conduction between the segments is negligible. Then, at equilibrium, each segment must satisfy the heat-balance equation, that is, solar-heat absorption + net heat input by radiation + heat transferred in by outside convection + heat transferred in by inside convection = 0, or... 

Ozone is an essential atmospheric trace substance. This gas plays an important role in the control of the radiation and heat balance of the stratosphere since it absorbs solar radiation with wavelengths shorter than about 0.3 jun. An important consequence of this absorption is that U V radiation lethal to living species does not reach the lower layers of the atmosphere. Because of the importance of atmospheric 03, its study started rather early. Junge (1963) mentions that Dobson and his associates measured total ozone (see later) beginning in the twenties by a European network consisting of six stations. Later, this network became world-wide and even the determination of the vertical distribution of 03 is now a routine measurement. Owing to these studies our knowledge of atmospheric ozone is rather substantial compared to that of other trace constituents. 

The effect of an increase in the extent of cloud cover on the atmospheric heat balance was numerically studied by Schneider (1972). He took into account the variation of the planetary albedo as well as the decrease of the infrared radiation loss. Schneider found that a more extensive cloud cover produces a temperature drop at low and midlatitudes if the height, thickness and albedo of the clouds remain unchanged. In contrast, over polar regions, where the intensity of incoming solar radiation is low and the surface albedo is great, an increase in the extent of cloud cover leads to a temperature rise in the surface air. 

Over a time span of a few years the heat balance of the earth can generally be considered to be in balance, which means that the incoming solar radiation, S, is balanced by the outgoing long wave radiation, F. What happens then when suddenly there is a change in either S or f Let us assume, for example, that there is a sudden increase in CO2 concentration to twice the present value. 

FIGURE 4.4 The Earth s annual and global mean energy balance (Kiehl and Trenberth 1997). Of 342 Wm-2 incoming solar radiation, 168 W m-2 is absorbed by the surface. That energy is returned to the atmosphere as sensible heat, latent heat via water vapor, and thermal infrared radiation. Most of this radiation is absorbed by the atmosphere, which, in turn, emits radiation both up and down. (Reprinted by permission of the American Meteorological Society.)... 

The incoming solar energy absorbed by the Earth is —44 units this is balanced by the net upward flux of infrared radiation of — 15 units, plus —6 unit loss by sensible heat conduction, and —23 unit loss by latent heat. The Earth emits — 115 units of infrared radiation to the atmosphere, whereas the atmosphere emits —170 units of infrared radiation, a net deficit of —55 units. Since the atmosphere absorbs —26 units of solar radiation, the net radiative loss from the atmosphere is —29 units this is made up for by the sensible and latent heat fluxes. The net radiative cooling of the atmosphere is thus balanced by the latent heat of condensation released in precipitation processes and by the convection and conduction of sensible heat from the surface. 

Aerosols may also play an important role in cHmate change. Natural aerosol emissions, similar to those caused by volcano eruptions and forest fires, can affect the radiation balance around the planet and, therefore, affect global temperatures quite distinctly from the heat directly released in such phenomena. Atmospheric aerosol emissions resulting from human industrial and deforestation activities can have the same effect, distinct from the associated greenhouse gas emissions. In both cases, these aerosols influence climate through the scattering of solar radiation, the absorption of terrestrial radiation, and through their effects on the properties of clouds [128, 129]. 

Fig. 2.13 Radiation and heat balance of the system earth-atmosphere. Percentages are given in relation to the incoming solar radiation (100% = 343 W m ). I interception of solar radiation by molecules/particles (p) clouds (c), and earth surface (e), D diffuse radiation by molecules/particles (p) clouds (c), R reflexion (albedo) by molecules/particles (p) clouds (c), and earth surface (e), IR infrared dissipation to space by molecules/particles (p) clouds (c), T terrestrial radiation back to space (without absorption), A absorption of terrestrial radiation by molecules, AB atmospheric back-radiation, SH and LH sensible and latent heat, resp.

It should also be understood that a profound perturbation of the earth s heat balance would be a probable consequence of nuclear war, were such an event ever to occur. The explosions in such a war might inject enough soot into the upper atmosphere to greatly reduce the amount of solar radiation reaching the surface for many weeks or months. The resulting temperature drop has been termed nuclear winter. A similar cooling may have occurred... 

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