Search results
Results from the WOW.Com Content Network
As mentioned above, when such ozone-depleting chemicals reach the stratosphere, they are dissociated by ultraviolet light to release chlorine atoms. The chlorine atoms act as a catalyst, and each can break down tens of thousands of ozone molecules before being removed from the stratosphere. Given the longevity of CFC molecules, recovery times ...
This means that over a 20-year span, the global warming potential of tropospheric ozone is much less, roughly 62 to 69 tons carbon dioxide equivalent / ton tropospheric ozone. [75] Because of its short-lived nature, tropospheric ozone does not have strong global effects, but has very strong radiative forcing effects on regional scales.
Oxygen and ozone continuously interconverted. Solar UV breaks down oxygen; molecular and atomic oxygen combine to form Ozone. 3. Ozone is lost by reaction with atomic oxygen (plus other trace atoms). The ozone–oxygen cycle is the process by which ozone is continually regenerated in Earth's stratosphere, converting ultraviolet radiation (UV ...
Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by absorption of light or photons. It is defined as the interaction of one or more photons with one target molecule that dissociates into two fragments.
Mass extinctions are very important to how life evolved on Earth. For example, when an asteroid hit the Earth 66 million years ago, the resulting dinosaur extinction led mammals to take their place.
The ozone depletion potential (ODP) of a chemical compound is the relative amount of degradation to the ozone layer it can cause, with trichlorofluoromethane (R-11 or CFC-11) being fixed at an ODP of 1.0. Chlorodifluoromethane (R-22), for example, has an ODP of 0.05. CFC 11, or R-11 has the maximum potential amongst chlorocarbons because of the ...
Many ozone-depleting substances are also greenhouse gases, some are thousands of times more powerful than carbon dioxide on a per-molecule basis over the short and medium term. [35] The increases in concentrations of these chemicals have produced 0.34 ± 0.03 W/m 2 of radiative forcing, corresponding to about 14% of the total radiative forcing ...
While there are many abiotic sources and sinks for O 2, the presence of the profuse concentration of free oxygen in modern Earth's atmosphere and ocean is attributed to O 2 production from the biological process of oxygenic photosynthesis in conjunction with a biological sink known as the biological pump and a geologic process of carbon burial involving plate tectonics.