Atmosphere water vapor, carbon dioxide

The atmospheric attenuation factor takes into account the influence of absorption and scattering by water vapor, carbon dioxide, dust, and aerosol particles. One can assume, as a conservative position, a clear, dry atmosphere for which = 1. 

Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases ... 

Radiation from the sun is in part reradiated as long wavelength (infrared) radiation from the Earth s surface and is absorbed by small amounts of water vapor, carbon dioxide, ozone, and other compounds in the atmosphere (Table 9.4). The ability of these components to intercept infrared radiation is shown in Figure 9.3. The upper boundary of the stippled area is the emission of the ocean s surface, whereas the lower boundary is the radiation measured at the distance of satellites. The difference is the net energy absorbed and trapped in the lower atmosphere. On a global average annual basis, this trapped infrared radiation is equal to 153 watts per square meter of the Earth s surface. 

Thinking Criticaiiy Which of the following gases would you expect to behave most like an ideal gas at room temperature and atmospheric pressure water vapor, carbon dioxide, helium, or hydrogen Explain. 

A minor constituent of the atmosphere. The most important trace gases contributing to the greenhouse effect are water vapor, carbon dioxide, ozone, methane, ammonia, nitric acid, nitrous oxide, ethylene, sulfur dioxide, nitric oxide, dichlorofluoromethane or Freon 12, trichlorofluoromethane or Freon 11, methyl chloride, carbon monoxide, and carbon tetrachloride, transient tracers... 

As infrared radiation heads away from Earth back toward space, about 84% of it is reabsorbed by molecules (water vapor, carbon dioxide, and methane) in our atmosphere and then reradiated back to Earth. This greenhouse blanket is critical to the balance of incoming and outgoing radiation that keeps our Earth s temperature tolerable for life. Thankfully, this phenomenon warms the surface of Earth to a comfortable average temperature of 15°C or about 59°F (compared to about 270°G in outer space) and allows us to flourish here. Without this warming, our oceans would be frozen solid ... 

To protect polymers while under severe conditions, such as high temperature, by an inert atmosphere (nitrogen, water vapor, carbon dioxide) welding of plastic materials is usually done by heated inert gases. 

Along with water vapor, carbon dioxide is the principal regulator of climate on Earth. Earth gives offbeat into outer space in the form of infrared radiation in order to maintain a state of thermal equilibrium. Carbon dioxide and water are both good absorbers of infrared radiation and contribute to what is called the greenhouse effect (see Chapter 29). Without those gases in the atmosphere, too much heat would be lost to outer space and Earths surface would be too cold to support the presence of liquid water. Life might still exist on Earth, but the cUmate would not be at the comfortable levels to which humans have become accustomed. 

In a vacuum, uncoated molybdenum metal has an unlimited life at high temperatures. This is also tme under the vacuum-like conditions of outer space. Pure hydrogen, argon, and hehum atmospheres are completely inert to molybdenum at all temperatures, whereas water vapor, sulfur dioxide, and nitrous and nitric oxides have an oxidizing action at elevated temperatures. Molybdenum is relatively inert to carbon dioxide, ammonia, and nitrogen atmospheres up to about 1100°C a superficial nitride film may be formed at higher temperatures in the latter two gases. Hydrocarbons and carbon monoxide may carburize molybdenum at temperatures above 1100°C. 

Both factors depend on the respective partial vapor pressures of water and carbon dioxide and upon the distance to the radiation source. The partial vapor pressure of carbon dioxide in the atmosphere is fairly constant (30 Pa), but the partial vapor pressure of water varies with atmospheric relative humidity. Duiser (1989) published graphs plotting absorption factors (a) against the product of partial vapor pressure and distance to flame (Px) for flame temperatures ranging from 800 to 1800 K. 

Atmospheric O2 has a partial pressure of 0.20 bar, and atmospheric water vapor is saturated with carbon dioxide. This dissolved CO2 forms carbonic acid, which generates a hydronium ion concentration of about 2.0 X 10 M. The Nemst equation allows calculation of the half-cell potential for the reduction of 02(g) under these... 

The atmosphere of modern Earth is thought to be very different from that of early Earth. Scientists conjecture that Earth s first atmosphere consisted of carbon dioxide, water vapor, nitrogen, and hydrogen sulfide, with trace amounts of ammonia and methane. The gases in the atmosphere are thought to have been released from the interior of the planet by volcanic eruptions. At this early... 

This is how to cope with any interference caused by the presence of atmospheric water vapor and carbon dioxide. Air samples are irradiated by light at two different wavelengths, one, which corresponds to a strong absorption band of water vapor and the other of carbon dioxide. From these measurements it is possible to compensate each measurement for interference from these two gases. It is of major importance that the water vapor interference compensation is accurate, which is ensured by a thorough calibration procedure. 

A Beckman IR-2 infrared spectrometer equipped with a sodium chloride prism was used. The wave-length scale was calibrated against known absorption maxima of liquid toluene and of atmospheric water vapor and carbon dioxide. Wave lengths are accurate to 0.02 fi. 

The orthonitrates, for example, sodium orthonitrate, readily react with atmospheric water vapor and carbon dioxide ... 

With the catalytic ozone analyzer described, ozone concentration can be measured by the temperature differential between two thermistors placed in the gas stream. One of the thermistors is coated with a catalyst promoting the decomposition of ozone the other is uncoated and is used as reference to the temperature of the gas. The two thermistors are part of a bridge circuit, the output of which is fed directly to a recorder. The instrument is not affected by the presence of water vapor, carbon monoxide, chlorine, nitrogen dioxide, sulfur dioxide, organic peroxides, hydrocarbon vapors, and combustion smokes at their usual concentrations in polluted atmospheres. 

FIGURE 11.42 Under atmospheric conditions, solid carbon dioxide does not melt it only sublimes. The cold carbon dioxide gas (—78°Cj causes nearby water vapor to condense and form a fog. 

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