Albedo, planetary

Hence, the radiative equilibrium temperature is sensitive to changes in the solar constant, planetary albedo, and the radiative properties of the earth-atmosphere-ocean system. In addition, changes internal to the earth-atmosphere-ocean system may alter the climate. Table I is an incomplete list of phenomena that individually or in concert could alter climate. 

Ear from being just the processing of water on Earth, this cycle is the basis for a wide range of meteorologic, geochemical, and biological systems. Water is the transport medium for all nutrients in the biosphere. Water vapor condensed into clouds is the chief control on planetary albedo. The cycling of water is also one of the major mechanisms for the transportation of sensible heat (e.g. in oceanic circulation) and latent heat that is released when water falls from the air. 

Clouds. Cloud feedback mechanisms are among the most complex in the climate system, due to the many disparate roles played by clouds, which control a large portion of the planetary albedo but also trap terrestrial radiation, reducing the energy escaping to space. To complicate matters further, different t5 es of clouds behave differently in the same environment. In the present climate mode, clouds have... 

On the average, the air over roughly half of the Earth s surface has an upward velocity and half has a downward velocity. This frontal activity (Section 7.5.3) and the interactions of marine air with the cold ocean surface result in about half of the Earth being covered by clouds and half being clear. As will be discussed in Chapter 17, this large fractional cloud cover is extremely important to the Earth s climate because it controls the planetary albedo (reflectivity). 

Twomey, S., Pollution and the Planetary Albedo, Atmos. Environ., 8, 1251-1256(1974). 

In our model, cap carbonates are explained as a result of high carbonate alkalinity in an ice-covered ocean, regardless of the specific mechanism for melting the snowball Earth. Ice could melt for a variety of reasons (e.g., greenhouse gases, a positive perturbation in solar forcing, a decrease in planetary albedo), but cap carbonates are expected to be produced as a result of the transition from high to low oceanic carbonate alkalinity. 

Pollack and Ackerman (1983) have reported the results of calculation with a one-dimensional radiative-convective model which predict the El Chichon cloud to have caused an increase of planetary albedo of 10%, a decrease in total radiation at the ground of 2-3%, and an increase in temperature of 3.5 degrees at the 30 mbar level. The GCM of the European Center for Medium Range Forecast was utilised to model the perturbation introduced by a fixed layer with an optical thickness of 0.15 added to the background a stratospheric warming of 3.5 C in the stratosphere and a cooling of about 0.1 C near the surface was obtained (Tanre and Geleyn, 1984). 

There is considerable interest in volcanic emissions of sulfur compounds because of the role of atmospheric sulfur chemistry in atmospheric radiation and climate, the hydrological cycle, acid precipitation, and air quality (see Chapter 8.14). Early theories on the climatic effects of eruptions considered that ash particles were responsible for raising the planetary albedo, but it is now clear that even fine tephra sediment rapidly from the atmosphere, and that the main protagonist in volcanic forcing of climate is the... 

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. 

In summary, the net outgoing radiative flux of about 235 Wm-2 corresponds to a blackbody temperature of 255K (—18°C). The surface emission of 390Wm-2 corresponds to a blackbody temperature of 288 K. Therefore, the surface temperature is about 33°C warmer than it would be if the atmosphere were completely transparent (and the planetary albedo were still 0.3). 

The term (TaF0) accounts for the reduction in flux first impinging on the top of the aerosol layer and the second factor of Ta accounts for the fact that the upward reflected flux is itself reduced by the transmittance Ta before it exits the top of the atmosphere. Thus the change in planetary albedo is... 

Note that ARp > 0. This means that for a nonabsorbing aerosol layer, the change in planetary reflectance is always positive that is, the presence of the aerosol layer leads to an increased planetary albedo over the that in its absence and, consequently, a cooling effect. 

That portion of the plankton community comprised of tiny plants (e.g., algae and diatoms), planetary albedo... 

Twomey, S. (1974) Pollution and the planetary albedo. Atmospheric Environment 8, 1251-1256,... 

Habitability and the HZ are first order functions of the stellar flux at the planet s location as well as the planet s atmospheric composition. The latter determines the albedo and the greenhouse effect in the atmosphere. The inner and outer boundaries of the HZ differ for clear and cloudy conditions because the overall planetary albedo A, is a function of the chemical composition of the clear atmosphere as well as the fraction of clouds, A = Adear + Adoud-... 

Eventually, the goal is to find Ip, and from that cloud or surface properties or the planetary albedo, provided we know the instrument response, the intensity of the solar radiation reflected from the diffuser, /d, and, of course, the measured values Sp and Sd- The task of finding the planetary albedo from such measurements is discussed in Section 8.6. The disadvantages of calibration with a diffusor plate are... 

A determination of the planetary albedo requires a large set of individual photometric measurements. Two approaches may be followed in collecting the data. In one approach the flux from a surface element is determined by recording the intensities emanating from that element in all directions and calculating the local flux according to the definition (Chandrasekhar, 1950),... 

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