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The ozone layer visible from space at Earth's horizon as a blue band of afterglow within the bottom of the large bright blue band that is the stratosphere, with a silhouette of a cumulonimbus in the orange afterglow of the troposphere. The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet ...
Ozone is formed in the stratosphere when oxygen gas molecules photodissociate after absorbing UVC photons. This converts a single O 2 into two atomic oxygen radicals. The atomic oxygen radicals then combine with separate O 2 molecules to create two O 3 molecules. These ozone molecules absorb UVB light, following which ozone splits into a ...
The highest levels of ozone in the atmosphere are in the stratosphere, in a region also known as the ozone layer between about 10 and 50 km above the surface (or between about 6 and 31 miles). However, even in this "layer", the ozone concentrations are only two to eight parts per million, so most of the oxygen there is dioxygen, O 2 , at about ...
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 ...
In the absence of plants, the rate of oxygen production by photosynthesis was slower in the Precambrian, and the concentrations of O 2 attained were less than 10% of today's and probably fluctuated greatly. The increase in oxygen concentrations had wide ranging and significant impacts on Earth's biosphere.
The ozone layer is contained within the stratosphere. In this layer ozone concentrations are about 2 to 8 parts per million, which is much higher than in the lower atmosphere but still very small compared to the main components of the atmosphere. It is mainly located in the lower portion of the stratosphere from about 15–35 km (9.3–21.7 mi ...
Decreases in ozone amounts lead to increases in UV radiation. Calculations of UV irradiance based on relationships with total ozone and total irradiance suggest that UV irradiance has increased since the early 1980s by 6-14% at more than 10 sites distributed over mid- and high latitudes of both hemispheres.
The ozone hole was much more seen as a "hot issue" and imminent risk compared to global climate change, [13] as lay people feared a depletion of the ozone layer (ozone shield) risked increasing severe consequences such as skin cancer, cataracts, [23] damage to plants, and reduction of plankton populations in the ocean's photic zone. This was ...