Earth atmospheric composition

The condensed phases also are important to the physical processes of the atmosphere however, their role in climate poses an almost entirely open set of scientific questions. The highest sensitivity of physical processes to atmospheric composition lies within the process of cloud nucleation. In turn, the albedo (or reflectivity for solar light) of clouds is sensitive to the number population and properties of CCN (Twomey, 1977). At this time, it appears impossible to predict how much the temperature of the Earth might be expected to increase (or decrease in some places) due to known changes in the concentrations of gases because aerosol and cloud effects cannot yet be predicted. In addition, since secular trends in the appropriate aerosol properties are not monitored very extensively there is no way to know... 

Meteors form when meteoroids enter the atmosphere. The mean orbital velocity of the Earth around the Sun is 29.7 kms-1, so a particle stationary in space will enter the Earth s atmosphere at this velocity. Gravity will further attract the particles up to a maximum of 11 kms-1 (the escape velocity) to make an entry velocity of order 40 kms-1 plus whatever additional velocity the particle may possess. This energy is converted into heat by the drag on the atmosphere, producing temperatures of order 2000 K - the glow seen from a shooting star. The final temperature depends on the properties of the particle, the atmospheric composition and the angle of incidence with the atmosphere. 

The mass spectrometer on the Pioneer mission in 1978 measured the atmospheric composition relative to CO2, the dominant atmospheric constituent. The and ratios were observed to be close to the Earth value, whereas the... 

POLLUTION (Air). Prior to the Industrial Revolution (circa 1840s). the composition of pure air making up Earth s surrounding atmospheres essentially remained constant for several thousand years. True, certain natural phenomena, such as volcanic eruptions, may have altered the atmospheric composition over relatively short lime spans. 

In addition to the transition phenomena mentioned so far in the present section, a variety of even larger scale processes might have operated during chemical evolution, namely, instabilities and bifurcations in the very atmospheric environment within which life emerged. As shown in the paper by Marcel Nicolet, the earth s atmosphere is the theater of a variety of complex chemical and transport phenomena. Moreover, as explained by Stanley L. Miller, the composition of the primordial atmosphere has certainly affected deeply the chemistry in the primitive oceans. Conversely, once life emerged the properties of the atmosphere changed radically, and this must have affected the further course of evolution. We refer to Prather et al.41 and North et al.42 for an account of present views on large scale transitions in the earth-atmosphere system. 

Studies of atmospheric properties using IR spectroscopy techniques have been reported in the literature for nearly 100 years. This paper presents a brief historical review of the development of this area of science and discusses the common features of spectrographic instruments. Two state of the art instruments on opposite ends of the measurement spectrum are described. The first is a fast response iri situ sensor for the measurement of the exchange of CO2 between the atmosphere and the earth s surface. The second is a rocketborne field-widened spectrometer for upper atmosphere composition studies. The thesis is presented that most improvements in current measurement systems are due to painstakingly small performance enhancements of well understood system components. The source, optical and thermal control components that allow these sensors to expand the state of the art are detailed. Examples of their application to remote canopy photosynthesis measurement and upper atmosphere emission studies are presented. 

At a certain altitude in the upper atmosphere, the temperature is estimated to be —100°C and the density just 10-9 that of the earth s atmosphere at S.T.P Assuming a uniform atmospheric composition, what is the pressure in torr at... 

Figure 10.48. Trends in the solar luminosity and temperature of the Earth. The upper temperature curve is calculated for an atmospheric composition like that of today whereas the lower temperature curve is for an airless Earth. The difference between the curves (the shaded region) represents the magnitude of the greenhouse effect. It is likely that atmospheric CO2 concentrations were higher in the earlier Precambrian and, consequently, temperatures were higher than shown. (After Kastinget al 1988.)...

Answer This hypothesis assumes that the rubisco reaction is the most important chemical reaction in determining the composition of the earth s atmosphere. This may once have been true, but in the modem world, many other processes, such as the burning of fossil fuels and destruction of tropical forests (by burning and other means), probably have at least as large an impact on atmospheric composition. To the extent that C4 plants contribute to global C02 fixation, they also tend to counterbalance the effect of rubisco on the balance of C02 and 02 in the atmosphere. 

Kasting JF, Howard MT. Atmospheric composition and climate on the early Earth. Phil. Trans. R. Soc. B 2006 361 1733-1742. 

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