Albedo of snow. Albedo of various surfaces. Albedo in realistic rendering

The total radiation reaching the earth's surface is not completely absorbed by it, but is partially reflected from the earth. Therefore, when calculating the arrival of solar energy for a place, it is necessary to take into account the reflectivity of the earth's surface. Reflection of radiation also occurs from the surface of clouds. The ratio of the entire flux of short-wave radiation Rk reflected by a given surface in all directions to the radiation flux Q incident on this surface is called albedo(A) given surface. This value

shows how much of the radiant energy incident on the surface is reflected from it. Albedo is often expressed as a percentage. Then

(1.3)

In table. No. 1.5 gives the albedo values for various types of the earth's surface. From the data in Table. 1.5 shows that freshly fallen snow has the highest reflectivity. In some cases, a snow albedo of up to 87% was observed, and in the conditions of the Arctic and Antarctic, even up to 95%. Packed, melted and even more polluted snow reflects much less. Albedo of various soils and vegetation, as follows from Table. 4, differ relatively slightly. Numerous studies have shown that the albedo often changes during the day.

The highest albedo values are observed in the morning and evening. This is explained by the fact that the reflectivity of rough surfaces depends on the angle of incidence of sunlight. With a vertical fall, the sun's rays penetrate deeper into the vegetation cover and are absorbed there. At a low height of the sun, the rays penetrate less into the vegetation and are reflected to a greater extent from its surface. The albedo of water surfaces is, on average, less than the albedo of the land surface. This is explained by the fact that the sun's rays (the short-wave green-blue part of the solar spectrum) penetrate to a large extent into the upper layers of water that are transparent to them, where they are scattered and absorbed. In this regard, the degree of its turbidity affects the reflectivity of water.

Table No. 1.5

For polluted and turbid water, the albedo increases noticeably. For scattered radiation, the albedo of water is on average about 8-10%. For direct solar radiation, the albedo of the water surface depends on the height of the sun: with a decrease in the height of the sun, the albedo value increases. So, with a sheer incidence of rays, only about 2-5% is reflected. When the sun is low above the horizon, 30-70% is reflected. The reflectivity of the clouds is very high. The average cloud albedo is about 80%. Knowing the value of the surface albedo and the value of the total radiation, it is possible to determine the amount of radiation absorbed by a given surface. If A is the albedo, then the value a \u003d (1-A) is the absorption coefficient of a given surface, showing what part of the radiation incident on this surface is absorbed by it.

For example, if a total radiation flux Q = 1.2 cal / cm 2 min falls on the surface of green grass (A \u003d 26%), then the percentage of absorbed radiation will be

Q \u003d 1 - A \u003d 1 - 0.26 \u003d 0.74, or a \u003d 74%,

and the amount of absorbed radiation

B absorb \u003d Q (1 - A) \u003d 1.2 0.74 \u003d 0.89 cal / cm2 min.

The albedo of the surface of water is highly dependent on the angle of incidence of the sun's rays, since pure water reflects light according to Fresnel's law.

Where Z P – zenith angle of the sun Z 0 is the angle of refraction of the sun's rays.

At the position of the Sun at the zenith, the albedo of the surface of a calm sea is 0.02. With an increase in the zenith angle of the Sun Z P albedo increases and reaches 0.35 at Z P\u003d 85. The excitement of the sea leads to a change Z P , and significantly reduces the range of albedo values, since it increases at large Z n due to an increase in the probability of rays hitting an inclined wave surface. Excitement affects the reflectivity not only due to the inclination of the wave surface relative to the sun's rays, but also due to the formation of air bubbles in the water. These bubbles scatter light to a large extent, increasing the diffuse radiation coming out of the sea. Therefore, during high sea waves, when foam and lambs appear, the albedo increases under the influence of both factors. Scattered radiation enters the water surface at different angles. cloudless sky. It also depends on the distribution of clouds in the sky. Therefore, the sea surface albedo for diffuse radiation is not constant. But the boundaries of its fluctuations are narrower 1 from 0.05 to 0.11. Consequently, the albedo of the water surface for total radiation varies depending on the height of the Sun, the ratio between direct and scattered radiation, sea surface waves. It should be borne in mind that the northern parts oceans are heavily covered with sea ice. In this case, the albedo of ice must also be taken into account. As you know, significant areas of the earth's surface, especially in middle and high latitudes, are covered with clouds that reflect solar radiation very much. Therefore, knowledge of the cloud albedo is of great interest. Special measurements of cloud albedo were carried out with the help of airplanes and balloons. They showed that the albedo of clouds depends on their shape and thickness. The albedo of altocumulus and stratocumulus clouds has the highest values. clouds Cu - Sc - about 50%.

The most complete data on cloud albedo obtained in Ukraine. The dependence of the albedo and the transmission function p on the thickness of the clouds, which is the result of the systematization of the measurement data, is given in Table. 1.6. As can be seen, an increase in cloud thickness leads to an increase in albedo and a decrease in the transmission function.

Average albedo for clouds St with an average thickness of 430 m is 73%, for clouds SWith at an average thickness of 350 m - 66%, and the transmission functions for these clouds are 21 and 26%, respectively.

The albedo of clouds depends on the albedo of the earth's surface. r 3 over which the cloud is located. From a physical point of view, it is clear that the more r 3 , the greater the flux of reflected radiation passing upward through the upper boundary of the cloud. Since albedo is the ratio of this flow to the incoming one, an increase in the albedo of the earth's surface leads to an increase in the albedo of clouds. The study of the properties of clouds to reflect solar radiation was carried out using artificial Earth satellites by measuring the brightness of clouds. The average cloud albedo values obtained from these data are given in table 1.7.

Table 1.7 - Average albedo values of clouds of different forms

According to these data, cloud albedo ranges from 29 to 86%. Noteworthy is the fact that cirrus clouds have a small albedo compared to other cloud forms (with the exception of cumulus). Only cirrostratus clouds, which are thicker, largely reflect solar radiation (r= 74%).

Lambertian (true, flat) albedo

True or flat albedo is the diffuse reflectance, that is, the ratio of the light flux scattered by a flat surface element in all directions to the flux incident on this element.
In the case of illumination and observation normal to the surface, the true albedo is called normal .

The normal albedo of pure snow is ~0.9, charcoal ~0.04.

geometric albedo

The geometric optical albedo of the Moon is 0.12, the Earth's is 0.367.

Bond (spherical) albedo

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Synonyms:

See what "Albedo" is in other dictionaries:

ALBEDO is the proportion of light or other radiation reflected from a surface. An ideal reflector has an albedo of 1, while a real reflector has a smaller number. Snow albedo ranges from 0.45 to 0.90; albedo of the Earth, from artificial satellites, ... ... Scientific and technical encyclopedic dictionary

- (arab.). A term in photometry indicating how much of the light rays a given surface reflects. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. albedo (lat. albus light) value characterizing ... ... Dictionary of foreign words of the Russian language

ALBEDO- (late lat. albedo, from lat. albus white), a value characterizing the ratio between the flux of solar radiation falling on various objects, soil or snow cover, and the amount of such radiation absorbed or reflected by them; ... ... Ecological dictionary

- (from late Latin albedo whiteness) a value that characterizes the ability of a surface to reflect the flow of electromagnetic radiation or particles incident on it. The albedo is equal to the ratio of the reflected flux to the incident one. In astronomy, an important characteristic ... ... Big Encyclopedic Dictionary

albedo- non-cl. albedo m. lat. albedo. white. 1906. Lexis. Inner white layer of citrus peel. Food industry. Lex. Brogg: albedo; SIS 1937: albe/before … Historical Dictionary of Gallicisms of the Russian Language

albedo- Characteristic of the reflectivity of the body surface; is determined by the ratio of the luminous flux reflected (scattered) by this surface to the luminous flux incident on it [Terminological dictionary for construction in 12 languages ... ... Technical Translator's Handbook

albedo- The ratio of solar radiation reflected from the surface of the earth to the intensity of radiation falling on it, expressed as a percentage or decimal fractions (the average albedo of the Earth is 33%, or 0.33). → Fig. 5 … Geography Dictionary

- (from late lat. albedo whiteness), a value characterizing the ability of the surface to. l. body to reflect (scatter) the radiation incident on it. There are true, or Lambertian, A., coinciding with the coefficient. diffuse (scattered) reflection, and ... ... Physical Encyclopedia

Exist., number of synonyms: 1 characteristic (9) ASIS synonym dictionary. V.N. Trishin. 2013 ... Synonym dictionary

A value characterizing the reflectivity of any surface; expressed by the ratio of the radiation reflected by the surface to the solar radiation that arrived at the surface (for chernozem 0.15; sand 0.3 0.4; average A. Earth 0.39; Moon 0.07) ... ... Glossary of business terms

ALBEDO

ALBEDO (Late Latin albedo, from Latin albus - white), a value that characterizes the ratio between the flux of solar radiation falling on various objects, soil or snow cover, and the amount of such radiation absorbed or reflected by them; reflect. body surface ability. The highest albedo (0.8-0.4) has dry snow, salt deposits, the average - vegetation, the smallest - water bodies (0.1-0.2).

Ecological encyclopedic dictionary. - Chisinau: Main edition of the Moldavian Soviet Encyclopedia. I.I. Grandpa. 1989

Albedo (from lat. albedo - whiteness) - the ratio of the amount of reflected radiation energy to the energy incident on the surface of the body. The albedo (of the entire spectrum as a whole) of forest communities varies, for example, within 10-15%. Wed light mode.

Ecological dictionary. - Alma-Ata: "Science". B.A. Bykov. 1983

ALBEDO [from lat. albus - light] - a value characterizing the reflectivity of any surface; It is expressed as the ratio of the radiation reflected by the surface to the solar radiation arriving at the surface. For example, A. chernozem - 0.15; sand 0.3-0.4; average A. of the Earth - 0.39; Moons - 0.07.

Ecological dictionary, 2001

Synonyms:

ALLELOGEN

See what "ALBEDO" is in other dictionaries:

Planets and some dwarf planets of the solar system Planet Geometric albedo Spherical albedo Mercury 0.106 0.119 Venus 0.65 0.76 Earth 0.367 0.39 Mars 0.15 0.16 Jupiter 0.52 0.343 Saturn 0.47 0.342 Uranus 0.51 0, 3 ... Wikipedia

Exist., number of synonyms: 1 characteristic (9) ASIS synonym dictionary. V.N. Trishin. 2013 ... Synonym dictionary

Books

Encyclopedic Dictionary of a Schoolchild,. What is the Earth's albedo? Does evolution continue today? Can you see the solar corona? When were the first ships created? How is the human brain arranged? Which train has a speed of...

Albedo of the Earth. Living matter increases the absorption of solar radiation by the earth's surface, reducing the albedo not only of the land, but also of the ocean. Land vegetation, as is known, significantly reduces the reflection of short-wave solar radiation into space. The albedo of forests, meadows, fields does not exceed 25%, but is more often determined by figures from 10% to 20%. Only a smooth water surface with direct radiation and moist chernozem (about 5%) has less albedo. However, bare dried soil or snow-covered land always reflects much more solar radiation than when they are protected by vegetation. The difference can reach several tens of percent. So dry snow reflects 85-95% of solar radiation, and the forest in the presence of a stable snow cover - only 40-45%.[ ...]

A dimensionless quantity that characterizes the reflectivity of a body or system of bodies. A. element of a reflective surface - the ratio (in percent) of the intensity (flux density) of radiation reflected by this element to the intensity (flux density) of radiation incident on it. This refers to diffuse reflection; in the case of directional reflection, one speaks not of A., but of the reflection coefficient. A distinction is made between integral A - for radiation over the entire range of its wavelengths, and spectral A - for individual parts of the spectrum. See also the albedo of the natural surface, the albedo of the Earth.[ ...]

EARTH ALBEDO. Percentage of solar radiation given off by the globe (together with the atmosphere) back into world space, to solar radiation entering the boundary of the atmosphere. The return of solar radiation by the Earth is composed of reflection from the earth's surface, scattering of direct radiation by the atmosphere into the world space (backscattering) and reflection from the upper surface of the clouds. A. 3. in the visible part of the spectrum (visual) - about 40%. For the integral flux of solar radiation, the integral (energy) A. 3. is about 35%. In the absence of clouds, visual A. 3. would be about 15%.[ ...]

Albedo is a value that characterizes the reflectivity of the surface of a body; the ratio (in %) of the reflected solar radiation flux to the incident radiation flux.[ ...]

The albedo of a surface depends on its color, roughness, humidity, and other properties. The albedo of water surfaces at a solar altitude above 60 ° is less than the albedo of land, since the sun's rays, penetrating into the water, are largely absorbed and scattered in it.[ ...]

The albedo of all surfaces, and especially water ones, depends on the height of the Sun: the smallest albedo occurs at noon, the largest - in the morning and evening. This is due to the fact that at a low altitude of the Sun, the proportion of scattered radiation in the composition of the total radiation increases, which is reflected from the rough underlying surface to a greater extent than direct radiation.[ ...]

ALBEDO is a value that characterizes the reflectivity of any surface. A. is expressed as the ratio of the radiation reflected by the surface to the solar radiation arriving at the surface. For example, A. chernozem - 0.15; sand - 0.3-0.4; average A. Earth - 0.39, Moon - 0.07.[ ...]

Here is the albedo (%) of various soils, rocks and vegetation cover (Chudnovsky, 1959): dry chernozem -14, wet chernozem - 8, dry sierozem - 25-30, wet sierozem 10-12, dry clay -23, wet clay - 16 , white and yellow sand - 30-40, spring wheat - 10-25, winter wheat - 16-23, green grass -26, dried grass -19, cotton -20-22, rice - 12, potatoes - 19.[ . ..]

Careful calculations of the land albedo of the early Pliocene epoch (6 million years ago) showed that at that time the albedo of the land surface of the Northern Hemisphere was 0.060 less than the modern one and, as evidenced by paleoclimatic data, the climate of this epoch was warmer and more humid; in the middle and high latitudes of Eurasia and North America, the vegetation cover was richer in species composition, forests occupied vast territories, in the north they reached the coasts of continents, in the south their border passed south of the border of the modern forest zone.[ ...]

Measurements using albedo meters located at a height of 1-2 m above the earth's surface make it possible to determine the albedo of small areas. The albedo values of long sections used in the calculations of the radiation balance are determined from an aircraft or from a satellite. Typical albedo values: wet soil 5-10%, chernozem 15%, dry clay soil 30%, light sand 35-40%, field crops 10-25%, grass cover 20-25%, forest - 5-20%, freshly fallen snow 70-90%; water surface for direct radiation from 70-80% with the sun near the horizon to 5% with high sun, for diffuse radiation about 10%; upper surface of clouds 50-65%.[ ...]

The maximum dependence of the albedo is observed on natural surfaces, on which, along with diffuse reflection, total or partial specular reflection is observed. These are smooth and slightly agitated water surface, ice, snow covered with infusion.[ ...]

Obviously, for a given single scattering albedo, the absorption will increase with an increase in the fraction of diffuse radiation and the average scattering multiplicity. For stratus clouds, as the zenith angle of the Sun increases, the absorption decreases (Table 9.1), since the albedo of the cloud layer increases and, apparently, the average scattering multiplicity of the reflected radiation decreases due to the strong forward extension of the scattering indicatrix. This result is consistent with calculations. For cumulus clouds, the inverse relationship is true, which is explained by the fact that at large clouds the proportion of diffuse radiation increases sharply. For Q=0°, the inequality Pst (¿1, zw+1) > РСu, r/+1) is valid, which is due to the fact that the radiation emerging through the sides of cumulus clouds has, on average, a lower scattering multiplicity. At = 60°, the effect associated with an increase in the average fraction of diffuse radiation is stronger than the effect due to a decrease in the average scattering multiplicity, so the reverse inequality is true.[ ...]

The independent pixel approximation (IPP) is used to calculate the spatially averaged albedo. The meaning of the approximation is that the radiation properties of each pixel depend only on its vertical optical thickness and do not depend on the optical thickness of neighboring regions. This means that we neglect the effects associated with finite pixel dimensions and horizontal radiation transfer.[ ...]

There are integral (energy) albedo for the entire radiation flux and spectral albedo for individual spectral sections of radiation, including visual albedo for radiation in the visible region of the spectrum. Since the spectral albedo is different for different wavelengths, A.E.P. changes with the height of the sun due to a change in the radiation spectrum. The annual course of A.E.P. depends on changes in the nature of the underlying surface.[ ...]

The derivative 911/ dC is the difference between the average albedo of stratus and cumulus clouds, which can be either positive or negative (see Fig. 9.5, a).[ ...]

We emphasize that at low values of humidity, the land albedo changes most sharply, and small fluctuations in the moisture content of the continents should lead to significant fluctuations in the albedo, and, consequently, in temperature. An increase in global air temperature leads to an increase in its moisture content (a warm atmosphere contains more water vapor) and to an increase in the evaporation of the waters of the World Ocean, which, in turn, contributes to precipitation on land. A further increase in temperature and humidity of the continents ensures the enhanced development of natural vegetation cover (for example, the productivity of tropical rainforests in Thailand is 320 centners of dry weight per 1 ha, and the desert steppes of Mongolia - 24 centners). This contributes to an even greater decrease in the albedo of the land, the amount of absorbed solar energy increases, as a result, there is a further increase in temperature and humidity.[ ...]

Using a pyranometer, you can also easily determine the albedo of the earth's surface, the amount of radiation leaving the cabin, etc. Of the instruments manufactured by the industry, it is recommended to use the M-80 pyranometer paired with the GSA-1 pointer galvanometer.[ ...]

The impact of cloud cover on the biosphere is diverse. It affects the Earth's albedo, transfers water from the surface of the seas and oceans to land in the form of rain, snow, hail, and also covers the Earth at night like a blanket, reducing its radiative cooling.[ ...]

The radiation balance can vary significantly depending on the albedo of the earth's surface, that is, on the ratio of reflected to incoming solar light energy, expressed in fractions of a unit. Dry snow and salt deposits have the highest albedo (0.8-0.9); average albedo values - vegetation; the smallest - water bodies (reservoirs and water-saturated surfaces) - 0.1-0.2. Albedo affects the unequal supply of solar energy to different-quality surfaces of the Earth and the air adjacent to it: the poles and the equator, land and ocean, various parts of the land, depending on the nature of the surface, etc.[ ...]

After all, it is necessary to take into account such important climatic parameters as albedo - a function of humidity. The albedo of marshes, for example, is several times smaller than the albedo of deserts. And this is clearly visible from satellite data, according to which the Sahara Desert has a very high albedo. So, it turned out that as the land gets wet, a positive feedback also occurs. Humidity is rising, the planet is warming up more, the oceans are evaporating more, more moisture is falling on land, humidity is rising again. This positive relationship is known in climatology. And I already mentioned the second positive connection when analyzing the dynamics of fluctuations in the level of the Caspian Sea.[ ...]

In the second version of the calculation, it was assumed that the degree of dependence of the albedo on the moisture reserves of the land decreased by 4 times, and the degree of dependence of the amount of precipitation on temperature decreased by a factor of two. It turned out that in this case the system of equations (4.4.1) also has chaotic solutions. In other words, the effect of chaos is significant and persists over a wide range of changes in the parameters of the hydroclimatic system.[ ...]

Let us consider further the influence of the ice cover. After the introduction of empirical data on the albedo, Budyko added to the equation relating temperature to radiation a term that takes into account the nonlinear dependence of the influence of the ice cover, which is the cause of the self-amplification effect.[ ...]

Multiple scattering plays a significant role in the formation of the radiation field in clouds, therefore, the albedo L and the transmission of diffuse radiation (reach large values even in those pixels that are located outside the clouds (Fig. 9.4, b, d). Clouds have different thicknesses, which in a given cloud field realization varies from 0.033 to 1.174 km The radiation field reflected by a single cloud spreads out in space and overlaps with the radiation fields of other clouds before it reaches the r-AH plane, where the albedo is determined The spreading and overlapping effects smooth out the albedo dependence so much from horizontal coordinates, that many details are masked and it is difficult to visually restore the real picture of the distribution of clouds in space using known albedo values (Fig. 9.4, a, b).The tops of the most powerful clouds are clearly visible, since in this case the influence of the above effects is not sufficient Albedo varies from 0.24 to 0.65, and its average value is 0.33.[ ...]

Due to multiple scattering in the "atmosphere-underlying surface" system, at high albedo values, the scattered radiation increases. In table. 2.9, compiled according to the data of K. Ya. Kondratiev, shows the values of the diffuse radiation flux And for a cloudless sky and various values of the albedo of the underlying surface (/ha = 30 °).[ ...]

The second explanation relates to reservoirs. They are included in the energy balance as complexes that change the albedo of the natural surface. And this is true, given the large areas of reservoirs that continue to grow.[ ...]

The radiation reflected from the earth's surface is the most important component of its radiation balance. The integral albedo of natural surfaces varies from 4-5% for deep water bodies at solar altitudes over 50° to 70-90% for pure dry snow. All natural surfaces are characterized by the dependence of the albedo on the height of the Sun. The greatest changes in albedo are observed from sunrise to its height above the horizon of about 30%.[ ...]

A completely different picture is observed in those spectral intervals where the cloud particles themselves absorb intensely and the single-scattering albedo is small (0.5 - 0.7). Since a significant part of the radiation is absorbed during each scattering event, the cloud albedo will be formed mainly due to the first few scattering multiplicities and, therefore, will be very sensitive to changes in the scattering indicatrix. The presence of a condensation nucleus is no longer capable of significantly changing the single-scattering albedo. For this reason, at a wavelength of 3.75 μm, the indicatrix effect of aerosol dominates and the spectral albedo of clouds increases by about 2 times (Table 5.2). For some wavelengths, the effect due to absorption by smoke aerosol can exactly compensate for the effect due to reduction in the size of cloud droplets, and the albedo will not change.[ ...]

The RPMS method, as we have seen, has a number of disadvantages associated with the effect of aerosol and the need to introduce corrections for the albedo of the troposphere and the underlying surface. One of the fundamental limitations of the method is the impossibility of obtaining information from parts of the atmosphere that are not illuminated by the Sun. The method for observing the intrinsic emission of ozone in the 9.6 μm band is deprived of this shortcoming. Technically, the method is simpler and allows remote measurements in the daytime and nighttime hemispheres, in any geographical area. The interpretation of the results is simpler in the sense that in the region of the spectrum under consideration, scattering processes and the influence of direct solar radiation can be neglected. Ideologically, this method belongs to the classical methods of inverse problems of satellite meteorology in the IR range. The basis for solving such problems is the radiative transfer equation, previously used in astrophysics. The formulation and general characteristics of the problems of meteorological sounding and the mathematical aspects of the solution are contained in the fundamental monograph by K. Ya. Kondratiev and Yu. M. Timofeev.[ ...]

U.K.R. for the Earth as a whole, expressed as a percentage of the influx of solar radiation to the upper boundary of the atmosphere, is called the Earth's albedo or the planetary albedo (of the Earth).[ ...]

[ ...]

True, a decrease in the content of water vapor also means a decrease in cloudiness, and clouds act as the main factor that increases the Earth's albedo or reduces it if the cloudiness becomes less.[ ...]

More accurate data are also needed on photodissociation processes (02, NO2, H2O2, etc.), i.e., on absorption cross sections and quantum yields, as well as on the role of aerosol light scattering and albedo in the dissociation process. The variability of the short-wave part of the solar spectrum over time is also of great interest.[ ...]

It is important to note that phytoplankton has a higher reflectivity (Lx 0.5) at solar radiation wavelengths L > 0.7 µm than at shorter X (Lx 0.1). Such a spectral course of albedo is associated with the need of algae, on the one hand, to absorb photosynthetically active radiation (Fig. 2.29), and on the other hand, to reduce overheating. The latter is achieved as a result of reflection by phytoplankton of longer wavelength radiation. It can be assumed that the formulas given in Section 2.2 are also suitable for calculating such parameters of heat flows as incoming and outgoing radiation, emissivity and albedo, provided that data on Ha and other meteorological elements also have the necessary higher time resolution (i.e. obtained with a shorter time step).[ ...]

From the physically reasonable assumption that the concentration of water vapor increases with increasing temperature, it follows that one can expect an increase in water content, the increase of which leads to an increase in the albedo of clouds, but has little effect on their long-wave radiation, with the exception of cirrus clouds, which are not completely black. This reduces the heating of the atmosphere and surface by solar radiation, and hence the temperature, and provides an example of a negative cloud-radiation feedback. Estimates of the value of the parameter X of this feedback vary over a wide range from 0 to 1.9 W-m 2-K 1 . It should be noted that an insufficiently detailed description of the physical, optical and radiative properties of clouds, as well as a disregard for their spatial heterogeneity, is one of the main sources of uncertainty in studies on the problem of global climate change.[ ...]

Another factor, which has also been neglected, is that the aerosol emitted can significantly attenuate solar radiation, which restores ozone in the atmosphere. An increase in albedo due to an increase in aerosol content in the stratosphere should lead to a decrease in temperature, which slows down the recovery of ozone. Here, however, it is necessary to perform detailed calculations with various aerosol models, since many aerosols noticeably absorb solar radiation, and this leads to some heating of the atmosphere.[ ...]

It is predicted that an increase in the content of CO2 in the atmosphere by 60% of the current level can cause an increase in the temperature of the earth's surface by 1.2 - 2.0 °C. The existence of a feedback between snow cover, albedo and surface temperature should lead to the fact that temperature changes can be even greater and cause a radical climate change on the planet with unpredictable consequences.[ ...]

Let a single flux of solar radiation fall on the upper boundary of the cloud layer in the X01 plane: and ср0 = 0 are the zenith and azimuth angles of the Sun. In the visible region of the spectrum, Rayleigh and aerosol light scattering can be neglected; Let us set the albedo of the underlying surface equal to zero, which approximately corresponds to the albedo of the ocean. Calculations of the statistical characteristics of the field of visible solar radiation, performed at non-zero albedo of the Lambertian underlying surface, are specially noted in the text. The scattering indicatrix is calculated according to the Mie theory for a model cloud Cx [1] and a wavelength of 0.69 μm. The cloud field is generated by a Poisso ensemble of points in space.[ ...]

The physical mechanism of instability is that the rate of accumulation of land moisture reserves due to precipitation exceeds the rate of their decrease due to river runoff, and an increase in land moisture, as shown above, causes a decrease in the Earth's albedo and then a positive feedback is realized, which leads to climate instability. In essence, this means that the Earth is constantly supercooled (glacial epochs, climate cooling) or overheated (warming and moistening of the climate, increased development of vegetation cover - the regime of "wet and green" Earth) ..[ ...]

It should be borne in mind that the accuracy of estimates of both the greenhouse effect as a whole and its components is still not absolute. It is not clear, for example, how one can accurately take into account the greenhouse role of water vapor, which, when clouds form, becomes a powerful factor in increasing the Earth's albedo. Stratospheric ozone is not so much a greenhouse gas as an anti-greenhouse gas, as it reflects approximately 3% of incoming solar radiation. Dust and other aerosols, especially sulfur compounds, weaken the heating of the earth's surface and the lower atmosphere, although they act in the opposite role for the heat balance of desert areas.[ ...]

So, the absorption and reflection of solar radiation by aerosol particles will lead to a change in the radiation characteristics of the atmosphere, a general cooling of the earth's surface; will affect the macro- and meso-scale circulation of the atmosphere. The appearance of numerous condensation nuclei will affect the formation of clouds and precipitation; there will be a change in the albedo of the earth's surface. The evaporation of water from the oceans, in the presence of an influx of cold air from the continents, will cause heavy precipitation in coastal areas and on continents; the source of energy capable of causing a storm will be the heat of evaporation.[ ...]

When solving the three-dimensional transport equation, periodic boundary conditions were used, which assume that the layer 0[ ...]

The surface layer of the troposphere experiences anthropogenic impact to the greatest extent, the main type of which is chemical and thermal air pollution. The air temperature is most strongly influenced by the urbanization of the territory. Temperature differences between the urbanized area and the surrounding undeveloped areas are related to the size of the city, building density, and synoptic conditions. There is an upward trend in temperature in every town and city. For large cities in the temperate zone, the temperature contrast between the city and the suburbs is 1-3 ° C. In cities, the albedo of the underlying surface decreases (the ratio of reflected radiation to the total) as a result of the appearance of buildings, structures, artificial coatings, solar radiation is more intensively absorbed here, accumulated by structures buildings absorbed heat during the day with its return to the atmosphere in the evening and at night. The heat consumption for evaporation decreases, as the areas with open soil cover occupied by green plantings are reduced, and the rapid removal of precipitation by rainwater sewer systems does not allow creating a moisture reserve in soils and surface water bodies. Urban development leads to the formation of air stagnation zones, which leads to its overheating; the transparency of the air also changes in the city due to the increased content of impurities from industrial enterprises and transport. The total solar radiation decreases in the city, as well as the oncoming infrared radiation of the earth's surface, which, together with the heat transfer of buildings, leads to the appearance of a local "greenhouse effect", i.e. the city is "covered" with a blanket of greenhouse gases and aerosol particles. Under the influence of urban development, the amount of precipitation is changing. The main factor in this is a radical decrease in the permeability for precipitation of the underlying surface and the creation of networks to divert surface runoff from the city. The importance of the huge amount of hydrocarbon fuel burned is great. On the territory of the city in the warm season, there is a decrease in the values of absolute humidity and the opposite picture in the cold season - in the city, the humidity is higher than outside the city.[ ...]

Let us consider some basic properties of complex systems, bearing in mind the conventionality of the term "complex". One of the main features of a system, which makes us consider it as an independent object, is that the system is always something more than the sum of its constituent elements. This is explained by the fact that the most important properties of the system depend on the nature and number of links between the elements, which gives the system the ability to change its state over time, to have quite diverse reactions to external influences. A variety of connections means that there are connections of different "weights or "strengths"; in addition, feedbacks with different signs of action arise in the system - positive and negative. Elements or subsystems connected by positive feedback tend, if they are not limited by other connections, to mutually reinforce each other, creating instability in the system. For example, an increase in the average temperature on Earth leads to the melting of polar and mountain ice, a decrease in albedo and the absorption of more energy from the Sun. This causes a further increase in temperature, an accelerated reduction in the area of glaciers - reflectors of the radiant energy of the Sun, etc. If it were not for numerous other factors affecting the average temperature of the planet's surface, the Earth could exist only either as "ice", reflecting almost all solar radiation , or as a red-hot, like Venus, lifeless planet.

The long-term albedo trend is directed towards cooling. In recent years, satellite measurements show a slight trend.

Changing the Earth's albedo is potentially a powerful impact on climate. As albedo, or reflectivity, increases, more sunlight is reflected back into space. This has a cooling effect on global temperatures. On the contrary, a decrease in albedo heats up the planet. A change in albedo of only 1% gives a radiative effect of 3.4 W/m2, comparable to the effect of CO2 doubling. How has albedo affected global temperatures in recent decades?

Albedo trends up to 2000

The Earth's albedo is determined by several factors. Snow and ice reflect light well, so when they melt, the albedo goes down. Forests have a lower albedo than open spaces, so deforestation increases albedo (let's say that deforestation will not stop global warming). Aerosols have a direct and indirect effect on albedo. The direct influence is the reflection of sunlight into space. An indirect effect is the action of aerosol particles as centers of moisture condensation, which affects the formation and lifetime of clouds. Clouds, in turn, affect global temperatures in several ways. They cool the climate by reflecting sunlight, but can also have a heating effect by retaining outgoing infrared radiation.

All these factors should be taken into account when summing up the various radiative forcings that determine the climate. Land-use change is calculated from historical reconstructions of changes in cropland and pasture composition. Observations from satellites and from the ground make it possible to determine trends in the level of aerosols and cloud albedo. It can be seen that cloud albedo is the strongest factor of the various types of albedo. The long-term trend is towards cooling, the impact is -0.7 W/m2 from 1850 to 2000.

Fig.1 Average annual total radiative forcing(Chapter 2 of the IPCC AR4).

Albedo trends since 2000.

One way to measure the Earth's albedo is by the Moon's ashen light. This is sunlight, first reflected by the Earth and then reflected back to Earth by the Moon at night. The Moon's ash light has been measured by the Big Bear Solar Observatory since November 1998 (a number of measurements were also made in 1994 and 1995). Fig. 2 shows albedo changes from satellite data reconstruction (black line) and from lunar ash light measurements (blue line) (Palle 2004).

Fig.2 Changes in albedo reconstructed from ISCCP satellite data (black line) and changes in the moon's ash light (black line). The right vertical scale shows the negative radiative forcing (ie cooling) (Palle 2004).

The data in Figure 2 is problematic. Black line, ISCCP satellite data reconstruction" is a purely statistical parameter and has little physical meaning because it does not take into account the non-linear relationships between cloud and surface properties and planetary albedo, nor does it include aerosol albedo changes, such as those associated with Mount Pinatubo or anthropogenic sulfate emissions(Real Climate).

Even more problematic is the albedo peak around 2003, visible in the moon's blue ashen light line. It strongly contradicts the satellite data showing a slight trend at this time. For comparison, we can recall the Pinatubo eruption in 1991, which filled the atmosphere with aerosols. These aerosols reflected sunlight, creating a negative radiative forcing of 2.5 W/m2. This has drastically lowered the global temperature. The ash light data then showed an exposure of almost -6 W/m2, which should have meant an even greater drop in temperature. No similar events occurred in 2003. (Wielicki 2007).

In 2008, the reason for the discrepancy was discovered. The Big Bear Observatory installed a new telescope to measure lunar ashlight in 2004. With the new improved data, they recalibrated their old data and revised their albedo estimates (Palle 2008). Rice. 3 shows the old (black line) and updated (blue line) albedo values. The anomalous peak of 2003 has disappeared. However, the trend of increasing albedo from 1999 to 2003 has been preserved.

Rice. 3 Change in the Earth's albedo according to measurements of the moon's ashy light. The black line is the albedo changes from a 2004 publication (Palle 2004). Blue line - updated albedo changes after improved data analysis procedure, also includes data over a longer period of time (Palle 2008).

How accurately is the albedo determined from the moon's ashen light? The method is not global in scope. It affects about a third of the Earth in each observation, some areas always remain "invisible" from the observation site. In addition, measurements are infrequent and are made in a narrow wavelength range of 0.4-0.7 µm (Bender 2006).

In contrast, satellite data such as CERES is a global measurement of the Earth's shortwave radiation, including all effects of surface and atmospheric properties. Compared to ash light measurements, they cover a wider range (0.3-5.0 µm). An analysis of the CERES data shows no long-term albedo trend from March 2000 to June 2005. Comparison with three independent datasets (MODIS, MISR and SeaWiFS) shows a "remarkable fit" for all 4 results (Loeb 2007a).

Rice. 4 Monthly changes in mean CERES SW TOA flux and MODIS cloud fraction ().

Albedo has been affecting global temperatures - mostly in the direction of cooling in a long-term trend. In terms of recent trends, the ashlight data shows an increase in albedo from 1999 to 2003 with little change after 2003. Satellites show little change since 2000. The radiative forcing from albedo changes has been minimal in recent years.