- Industry: Education
- Number of terms: 13055
- Number of blossaries: 0
- Company Profile:
Founded in 1879 and named after Texas' greatest hero General Sam Houston, Sam Houston State University is public shcool within the Texas state university system and located in Huntsville, Texas.
It's a multicultural institution that offers 79 bachelorette degree programs, 54 masters and five ...
H<sub>2</sub>S, hydrogen sulfide is a reducing species, which is relatively unstable but survives for rather a long time owing to its slow reaction with atmospheric oxygen. This sulfur-containing gas is a major participant in gas to particle conversion in the atmosphere. Many sulfur-containing gases are reactive and thus are rapidly converted to sulfuric acid.
Industry:Chemistry; Weather
Having the characteristic of drawing moisture from the atmosphere.
Industry:Chemistry; Weather
HBr, In the stratosphere, ozone is continuously being formed via the Chapman mechanism. However, halogen radicals such as atomic bromine and atomic chlorine (released from anthropogenic and some natural sources) catalyze the breakdown of ozone which results in a net ozone loss:
O<sub>3</sub> + Br ----> BrO + O<sub>2</sub>
A reservoir species is a compound whose formation breaks the destruction cycle by taking the halogen radical out of the cycle. Two examples are HCl and HBr. Unfortunately, the success of HBr as a reservoir species is very limited due to the fact that it, unlike HCl, photodissociates quickly and easily. Thus, the ozone depleting effects of bromine are, atom for atom, more severe than those of chlorine.
Industry:Chemistry; Weather
HCFCs, chemical species slated to replace CFCs in the near future in most Western nations. When the normal chlorofluorocarbons (see above) reach the stratosphere and are photo-decomposed, their released chlorine radicals destroy the natural ozone that acts as our umbrella to shield the Earth from ultraviolet radiation (see chlorine and ozone). With one or more hydrogen-carbon bonds, HCFCs are still useful as replacement for CFCs in most applications. However, this bonding structure makes HCFCs much more chemically unstable--as compared to CFCs--and therefore subject to hydroxyl radical and ozone attack early in their gas phase career in the atmosphere. In fact they react in the troposphere instead of the stratosphere. Their atmospheric lifetime is shorter than CFCs and they, therefore, have a smaller chance of reaching the stratosphere where their chlorine could be released by destructive photolysis and enter the catalytic ozone destruction cycle.
Industry:Chemistry; Weather
HCl, anhydrous hydrochloric acid. Its molecular weight is 36. 47 g/mol; it is a colorless, corrosive gas. Hydrogen chloride is a covalent bonded nonflammable gas and ionizes almost completely when dissolved in water. When dissolved in water, hydrogen chloride forms a strong acid, hydrochloric acid. In the stratosphere, HCl acts as a reservoir species temporarily removing chlorine radicals from a catalytic ozone destruction cycle. (See ozone and chlorine. )
Industry:Chemistry; Weather
Heavy winds characterized by a pronounced seasonal change in direction. Winds usually blow from land to sea in the winter, while in the summer, the flow reverses and precipitation is more common. Monsoons are most typical in India and southern Asia.
Industry:Chemistry; Weather
HF, A clear, corrosive liquid that has an extremely pungent odor and forms dense white vapor clouds if released. Both the liquid and the vapor can cause severe burns to all parts of the body, and medical treatment is required for all exposures. In fact, HF burns covering only 2% of the body can be fatal. If this chemical comes in contact with glass, concrete and other silicon-containing materials, it yields silicon tetrafluoride gas. In general, this chemical is used to produce environmentally safer fluorocarbon products, chemical derivatives, and fluoropolymers. Environmentally speaking, hydrofluoric acid is much too reactive to ever reach the upper atmosphere, and tropospheric sources therefore do not interfere with the ozone layer. Hydrogen fluoride, however, is produced in situ in the stratosphere by the photolytic destruction of anthropogenic CFCs. And while this process also frees atomic chlorine which catalytically destroys ozone, Cl can be sequestered as HCl, and temporarily removed from the O<sub>3</sub> destruction cycle. Analogously HF also forms but unlike the chlorine reservoir species HCl which is eventually broken apart by hydroxyl radical, HF is too stable for th OH dot attack, and so the only significant stratospheric sink is eventual diffusion into the troposphere.
Industry:Chemistry; Weather
High clouds that are formed entirely from ice crystals. They appear delicate and wispy and can reach a height of 35,000 feet (10,700 meters). Other types of cirrus clouds include cirrostratus and cirrocumulus. Cirrostratus is a thin sheet of cloud that often causes a halo to appear around the sun or moon. Cirrocumulus look like many small tufts of cotton; however, these clouds rarely form.
Industry:Chemistry; Weather
Highly reactive atoms or molecules with incomplete (electronic) octets and therefore uneven numbers of electrons. (In the case of hydrogen radical this is an incomplete duet. ) Free radicals species are very electrophilic, will abstract atoms from other molecules to complete their octets, and will, in the process, generate new radicals. In the atmosphere, most free radical species have short life times; however, they can promote the conversion of oxygen to ozone and also take part in the catalytic cycle of ozone destruction (see chlorine and chlorine monoxide). (Also see radicals. )
Industry:Chemistry; Weather
HNO<sub>3</sub>, this is a corrosive, non-volatile, and inorganic acid. It is a strong acid (dissociates completely in aqueous solution) and is also an oxidizer. In the atmosphere it is formed by the conversion of nitrogen monoxide into nitrogen dioxide, and ultimately into nitric acid:
2NO + O<sub>2</sub> --> 2NO<sub>2</sub>
3NO<sub>2</sub> + H<sub>2</sub>O --> 2HNO<sub>3</sub> + NO
Nitrogen monoxide in this process most often come from (fossil fuel-based) combustion processes that use atmospheric air (containing 78. 1% N<sub>2</sub>) which combines with atmospheric oxygen in those high temperature combustion process (see nitrogen monoxide and nitrogen dioxide entries below). Nitric acid is highly water soluble. This solubility with water allows easy removal of nitric acid from the troposphere by atmospheric precipitation. Commonly, this is referred to as acid rain or snow. Nitric acid has a relatively low concentration in the atmosphere but provides an important role in the production of sulfuric acid. It acts as a catalyst in the conversion of sulfur dioxide to sulfuric acid. Sulfuric acid is usually formed within cloud droplets by oxidation of dissolved sulfur dioxide again most often released by fossil fuel combustion.
Industry:Chemistry; Weather
