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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 ...
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 ...
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 ...
Ozone remains depleted in the midlatitudes of both hemispheres. The global-average total column ozone amount for the period 1997-2001 was approximately 3% below the pre-1980 average values. Models capture the observed long-term ozone changes in northern and southern midlatitudes.
The formation of the ozone layer is also caused by photodissociation. Ozone in the Earth's stratosphere is created by ultraviolet light striking oxygen molecules containing two oxygen atoms (O 2), splitting them into individual oxygen atoms (atomic oxygen). The atomic oxygen then combines with unbroken O 2 to create ozone, O 3. [17]
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 ...
The null cycle can be broken in the presence of certain molecules, leading to a net increase or decrease in ozone in the stratosphere. One important example is NO x emissions into the stratosphere. The NO x reacts with both the atomic oxygen and ozone leading to a net decrease in ozone. [2] This is particularly important at night when NO 2 ...
The United Nations designates a specific theme each year for the International Day for the Preservation of the Ozone Layer to highlight different facets of ozone protection. 2015: 30 Years of Healing the Ozone Together. [6] 2016: Ozone and climate: Restored by a world united. [7] 2017: Caring for all life under the sun. [8] 2018: Keep Cool and ...