A Free book from before climate politicisation

At last wuwt comes up with something useful:

 Rudolph Geiger “The Climate Near The Ground” 2nd edition 1950?

A very coprehensive book well worth the download. There is too much to quote but of interest is the hot-house effect:

The heat exchange between ground and air and the heat exchange within the air layer near the ground is caused not only by heat conduction (see Chapter 3) and convection (see Chapter 4) but also by the exchange of heat in consequence of the long wave heat radiation of the surface and the air itself.
The absorption of the long wage radiation emitted from the ground during day and night is caused (as has already been briefly mentioned in Chapter 2, p. 13) primarily by water vapor and carbon dioxide of the air. Fig. 19 shows the absorption spectrum of the two gases according to F. Schnaidt (127). In the upper portion (of the figure) the absorption coefficient of water vapor, equivalent to o.oi cm of precipitable water is represented as dependent upon the wave length X. The visible portion of the spectrum (0.4 0.8u) lies on the left side beyond the figure. In this most effective portion of the solar radiation the absorption of water vapor is negligible. The first absorption band is at 3, another, more effective, is between 5 and 9u with the maximum at 6.3 /A. Beyond a comparatively diathermic portion the absorption increases, starting from 12 //,, rapidly and continues remaining high. Carbon dioxide, whose absorption coefficient is represented in the lower portion of Fig. 19 (but in another scale regarding wave length), shows two bands with sharp boundaries, at 4.3 and 14.7 //,. The comparison of the absorption spectrums with the array of numbers shown above for the wave length of the strongest outgoing radiation shows that these fall in the region of rapidly increasing absorption. The absorbed part of the radiation hence varies with the temperature of the radiating surface.
The relationship between the emissivity ' of a body and its absorptivity is constant at a given wave length and temperature, according to Kirchhoff's law, and the air is thus a "band radiator," since it absorbs in bands. It is thus different from solid ground, for the latter is, in the region of long wave lengths, practically a "black body"; as will be shown in Chapter 13 (see page 130), it absorbs all radiation falling upon it. It is thus also a "black body radiator," that is to say it emits at all wave lengths indifferently. This difference between the black body radiation of the ground and the band radiation of the air leads to the phenomenon which G. Falckenberg (//6, 118) has called the wavelength transformation. When for instance the earth's surface is cooled by outgoing radiation at night, heat is returned to it by the warm air next to the ground in the form of band radiation. The ground surface which receives this energy transforms it into radiation with a practically continuous spectrum as it leaves the solid earth which is in effect a "black body." This radiation emitted by the ground meets a two-fold fate. As much of it as falls within that part of the continuous spectrum belonging to the water vapor and carbon dioxide cannot get out. It is absorbed. Part of this energy is given to the higher air layers and passes away into space. Another part gets back to the earth. Those wavelengths, however, which do not belong to the bands mentioned, pass through the air unhindered. Their energy is "effectively" radiated. The ground consequently is cooled, but only the lowest air-layer is cooled, for it can now return energy through band radiation to the once more cooler ground. This, in turn, gives back only a part as utilizable to the air, while it loses a part for good as a result of wavelength transformation, and itself cools off still more.
According to G. Falckenberg (118) and F. Schnaidt (127) the depth of the long wave radiation is very small. It is only a few meters and for some wave lengths even less than 85 cm.! The air layers at a somewhat greater distance from the ground do not cool immediately by radiation towards the cold ground, but by radiating towards the lower air layers, which, on their own part, are already cooled by radiation. Therefore, the cooling process is propagated very slowly upwards. Hence, E. Stoecker speaks of a radiative pseudo conduction] as with the genuine heat conduction, in consequence of the short path of the molecules, the heat is conducted only slowly, also with radiative pseudo conduction heat is transferred slowly in consequence of the small range of the long waves.
The effect of wave length transformation extends, it must be concluded, to the daytime, likewise. Solar radiation causes a rise of the temperature of the earth's surface; this temperature rise leads to an increase of ground radiation, which occurs as an almost continuous spectrum. A part of this ground radiation is taken in by the absorbing bands of the air and this part causes a slowly moving heat wave to rise from the ground, which is therefore attributable to radiative pseudo-conduction. The portion of the ground radiation not absorbed in the air is lost to the earth.

No comments:

Post a Comment