Atmosphere layers

Fig. 7-1 Atmospheric vertical structure including temperature composiHon and conventional names of atmospheric layers or altitude regions.

If the acceleration is positive, our parcel is buoyant and spontaneous convection occurs. The atmospheric layer is said to be unstable. Negative acceleration implies that a small displacement, Az, results in the parcel accelerating back toward its initial position and therefore indicates stability. If dP /dz is that for an adiabatic test parcel dT /dz = —gM/Cp and dl/dz that of the existing layer, then for dP/dz > —9.8 K/km is stable and for d7/dz < — 9.8K/km is unstable. The 9.8 K/km figure then provides a simple benchmark for static stability of dry air. 

The error of this approximation is less than 0.01% for relevant global mean temperatures (see the Appendix). The thickness of the atmospheric layers, which is increasing with the altitude, is correlated to the optical depth of the... 

We stress that any possible abundance errors produced by uncertainties in the near-UV continuum, 3D and/or non-LTE effects are not critical for the present analysis. These errors will cancel out when forming abundance ratios from lines formed in the same atmospheric layer. This philosophy led Tomkin and Lambert (1984) to derive C/O ratio from the bands NH 3360 and CH 4300 A. 

The second method uses pulsed lasers and the laser-induced fluorescence is detected by telescope. If the telescope and the laser source have a definite base distance, the crossing of laser beam and the acceptance angle of the telescope define the height of the atmospheric layer at which fluorescence is detected. There is also the technique of delayed coincidence, where the time interval between laser pulse and detected fluorescence pulse determines the distance of the observed molecules from the observer (Lidar)... 

Troposphere The atmospheric layer closest to Earths surface, containing 90 percent of the atmospheres mass and essentially all water vapor and clouds. 

Stratosphere The atmospheric layer that lies just above the troposphere and contains the ozone layer. 

In which atmospheric layer does all our weather occur ... 

The primary sources that are responsible for the presence of this family of compounds in the atmosphere emit NH3, N20, and NO to the troposphere, the lowest level of the atmosphere, which extends to approximately 10 km from the earth s surface. NH3 seems to undergo very little chemistry in the atmosphere except for the formation of aerosols, including ammonium nitrate and sulfates. NH3 and the aerosols are highly soluble and are thus rapidly removed by precipitation and deposition to surfaces. N20 is unreactive in the troposphere. On a time scale of decades it is transported to the stratosphere, the next higher atmospheric layer, which extends to about 50 km. Here N20 either is photodissociated or reacts with excited oxygen atoms, O (lD). The final products from these processes are primarily unreactive N2 and 02, but about 10% NO is also produced. The product NO is the principal source of reactive oxidized nitrogen species in the stratosphere. 

The main objective of the PAUR I project was to investigate how increased penetration of UV-B solar radiation through the atmosphere, resulting from stratospheric ozone depletion, affects photochemical production and chemical transformation of ozone and other photochemically active species in the lower atmospheric layers. 

As part of some international and national projects, many measurements of atmospheric optical thickness were carried out. By using passive satellite sensors, estimates can be averaged vertically over a surface pixel. Therefore, to get a deeper understanding of the optical thickness of atmospheric layers, aircraft measurements are made which give the vertical distributions both of tropospheric aerosols and other characteristics of the atmosphere. Among successful airborne experiments we should highlight the ITOP, SHADE, and SAMUM experiments. These experiments made it possible to study the transformation of aerosols during the distant transport of smoke and desert dust. 

The atmospheric layer directly above the troposphere is the stratosphere, the average temperature of which increases from -56°C at its boundary with the troposphere to -2°C at its upper boundary, around 50 km. The reason for this increase is absorption of solar ultraviolet energy by ozone (03), levels of which may reach around 10 ppm by volume in the midrange of the stratosphere. 

Figure 1 Vertical structure of the atmosphere. The vertical profile of temperature can be used to define the different atmospheric layers...

The SDA dispersiveness in the air surface layer is determined by natural dispersiveness of soil as a source of aerosol, and by effectiveness of the sand-jet effect of saltating particles. The formation of the real size distribution of SDA in this atmospheric layer is determined by the processes of sedimentation, impingement, condensation and adsorption of gases and vapors, capture and sedimentation on obstacles and surfaces [6]. Real size distributions of soil-erosion aerosols (SEA) can be described by the power law ... 

Fig. 4. Calculated temperature at the earth s surface (T.) and in three atmospheric layers (Ti, Tj and T3) as function of the atmospheric smoke content. A relative smoke content of unity corresponds to 1.2 g of smoke per m surface area. Two sets of calculations are presented for hypothetical surface albedos of 30% and 50%.

Although most evidence indicates that the measured BrO is located in the free troposphere, these data do not exclude other contributions, e.g., from the marine boundary layer. Especially over ocean regions the sensitivity of GOME to BrO in lower atmospheric layers in reduced and a contribution of BrO in the MBL as measured by Leser et al. (2003) cannot be excluded (see, e.g.. 

Ozone is a gas that occurs naturally in relatively large concentrations in the upper-atmospheric layer known as the stratosphere. The stratosphere is between 5-10.6 mi (8-17 km) to about 31 mi (50 km) above the earth s surface. Stratospheric ozone is very important to life on the surface of Earth because it absorbs much of the incoming solar ultraviolet radiation, and thereby shields organisms from its deleterious effects. Since the mid-1980s, there has been evidence that concentrations of stratospheric ozone are diminishing as a result of complex photochemical reactions involving chloroflno-rocarbons (CFCs). These persistent chemicals are synthesized by humans and then emitted to the lower atmosphere, from where they eventually reach the stratosphere and deplete ozone. 

The boundaries between atmospheric layers are not rigidly fixed for example, the boundary between the troposphere and the stratosphere varies from an average of about 7,500 m (25,000 ft) near the poles to 17,000 m (55,000 ft) near the equator, and fluctuates seasonally. A reference profile, the Standard Atmosphere, is defined by the International Civil Aviation Organization to represent typical atmospheric conditions at midlatitudes (Table 4-1). At sea level, the Standard Atmosphere exerts a pressure of 760 mm of mercury (1 atm) and has a temperature of 15°C (59°F). (Note that English units are still in widespread use in the meteorology and aviation communities in the United States.) Pressure decreases approximately exponentially with increasing altitude at 5500 m (18,000 ft), pressure is half that at sea level. 

FIGURE 4-10 Emission of pollutants from a smokestack, a typical continuous source, under a variety of meteorological conditions. The dry adiabatic lapse rate is represented as a dashed line and the actual measured lapse rate as a solid line in the left panels. Vertical mixing is strongest when the adiabatic lapse rate is less than the actual measured lapse rate and the atmosphere is unstable (top). Weak lapse is a term used to express the existence of a stable atmosphere, which results in less vigorous vertical mixing. An inversion, in the third panel from the top and in part of the last three panels, results in a very stable atmospheric layer in which relatively little vertical mixing occurs (Boubel et al, 1994). 

In addition to product isomers, the crossed beam technique also provides information on the highly unstable reaction intermediates. The identified intermediates have been characterized by resorting to ah initio electronic structure calculations all the reaction intermediates are doublet radicals, internally excited, and hence highly reactive in planetary atmospheres. Although under the experimental single collision conditions the gas is too rarefied to allow three-body collisions, the collision induced stabilization of the intermediates is possible in Titan s dense atmosphere. Notably, these free radicals have unknown spectroscopic properties which could make them responsible for the orange color of the upper atmospheric layers. 

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