Kivi, E. Larsen, P. Levelt, A. Makshtas, C. McElroy, H. Nakajima, M. Parrondo, D. Tarasick, P. Walker, and N. Unprecedented Arctic ozone loss in Nature , , Bernhard, G. Manney, V. Fioletov, J. Johnsen, T. Koskela, K. The next layer, the stratosphere stratosphere The region of the atmosphere above the troposphere.
The stratosphere extends from about 10km to about 50km in altitude. Commercial airlines fly in the lower stratosphere. The stratosphere gets warmer at higher altitudes. In fact, this warming is caused by ozone absorbing ultraviolet radiation.
Warm air remains in the upper stratosphere, and cool air remains lower, so there is much less vertical mixing in this region than in the troposphere. Most commercial airplanes fly in the lower part of the stratosphere. Health and Environmental Effects of Ozone Depletion. Ozone Layer Research and Technical Resources. Information for students about the Ozone Layer. Addressing Ozone Layer Depletion. Adapting to a Changed Ozone Layer. Phasing Out Ozone-Depleting Substances.
Managing Refrigerant Emissions. Most atmospheric ozone is concentrated in a layer in the stratosphere, about 9 to 18 miles 15 to 30 km above the Earth's surface see the figure below. Ozone is a molecule that contains three oxygen atoms.
At any given time, ozone molecules are constantly formed and destroyed in the stratosphere. The total amount has remained relatively stable during the decades that it has been measured. The ozone layer in the stratosphere absorbs a portion of the radiation from the sun, preventing it from reaching the planet's surface. UVB is a kind of ultraviolet light from the sun and sun lamps that has several harmful effects. It is a cause of melanoma and other types of skin cancer.
It has also been linked to damage to some materials, crops, and marine organisms. The ozone layer protects the Earth against most UVB coming from the sun. It is always important to protect oneself against UVB, even in the absence of ozone depletion, by wearing hats, sunglasses, and sunscreen.
However, these precautions will become more important as ozone depletion worsens. UVB has been linked to many harmful effects , including skin cancers, cataracts, and harm to some crops and marine life. Scientists have established records spanning several decades that detail normal ozone levels during natural cycles. Three years of research proved a group of chemicals known as chlorofluorocarbons or CFCs to be the culprit.
The Montreal Protocol phased out the utilisation of CFCs and in , an amendment to the treaty placed a complete ban on their use. As of this writing, countries have signed up. Had there been no Montreal Protocol, the ozone hole would have covered the earth, meaning a stroll on a bright summer day could have caused a sunburn on exposed skin in less than 10 minutes. Prof Wenger is a walking encyclopaedia when it comes to the ozone layer, its incremental recovery and substances that are impeding it.
The rest of the molecules are mostly nitrogen and oxygen, like the air we breathe. There isn't much of it, but ozone is powerful, able to block the most harmful radiation. Ozone absorbs the most energetic wavelengths of ultraviolet light , known as UV-C and UV-B, wavelengths that harm living things. Oxygen molecules absorb other forms of ultraviolet light, too. Together, ozone and oxygen molecules are able to absorb 95 to When UV light is absorbed by oxygen and ozone, heat is generated, which is why the stratosphere gets warmer with altitude.
The ozone layer in the stratosphere shields life on Earth from most UV-B and UV-C, the most harmful varieties of ultraviolet radiation. Credit: NASA. Ozone and oxygen molecules are constantly being formed, destroyed, and reformed in the ozone layer as they are bombarded by ultraviolet radiation UV , which breaks the bonds between atoms, creating free oxygen atoms.
Free oxygen atoms are highly reactive, meaning that they bond easily with other molecules. If a free oxygen atom bumps into an oxygen molecule O 2 , it will form ozone O 3.
If a free oxygen atom bumps into another oxygen atom, it will form an oxygen molecule O 2.
0コメント