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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 cycle illustrated over image by NASA astronaut Scott Kelly. Ozone is a ubiquitous yet highly reactive molecule in the atmosphere. Such a highly reactive oxidizer would normally be dangerous to life but ozone's concentration at sea level is usually not high enough to be toxic.
The thermosphere (or the upper atmosphere) is the height region above 85 kilometres (53 mi), while the region between the tropopause and the mesopause is the middle atmosphere (stratosphere and mesosphere) where absorption of solar UV radiation generates the temperature maximum near an altitude of 45 kilometres (28 mi) and causes the ozone layer.
Ozone in the ozone layer filters out sunlight wavelengths from about 200 nm UV rays to 315 nm, with ozone peak absorption at about 250 nm. [55] This ozone UV absorption is important to life, since it extends the absorption of UV by ordinary oxygen and nitrogen in air (which absorb all wavelengths < 200 nm) through the lower UV-C (200–280 nm ...
The Weather Channel A hole in our atmosphere more than twice the size of the United States is finally beginning to close up, and might even be completely gone by the end of the century, according ...
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]
Most of the ozone production occurs in the tropical upper stratosphere and mesosphere. The total mass of ozone produced per day over the globe is about 400 million metric tons. The global mass of ozone is relatively constant at about 3 billion metric tons, meaning the Sun produces about 12% of the ozone layer each day. [1]
[9] [10] [11] [7] Biology is the main driver of O 2 flux on modern Earth, and the evolution of oxygenic photosynthesis by bacteria, which is discussed as part of the Great Oxygenation Event, is thought to be directly responsible for the conditions permitting the development and existence of all complex eukaryotic metabolism. [12] [13] [14]