CFCs rise and gradually accumulate in the stratosphere where they are broken down by the sun's ultraviolet light, so releasing chlorine atoms. The chlorine attacks the ozone, one chlorine atom can help to destroy , ozone molecules. The Montreal Protocol banning CFCs was signed by leading industrial nations in though the ozone layer continued to thin for the next decade as countries sought to reduce their use.
As reported in The Independent in 'China raised its emissions from 29, tons in to 51, in ; South Korea from 8, to 9, tons and the Philippines from 1, to 2, tons'. But it's not just with ozone that CFCs wreak havoc, they're also a potent greenhouse gas. In research published in the journal Nature Geoscience linked the ban to a 'pause' or slowdown in temperature increases since the mid s. India bets its energy future on solar—in ways both small and big.
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UVB is mostly absorbed by ozone, although some reaches the Earth. UVC is completely absorbed by ozone and normal oxygen. Scientific Assessment of Ozone Depletion: The Earth's atmosphere is composed of several layers.
The lowest layer, the troposphere troposphere The region of the atmosphere closest to the Earth. The troposphere extends from the surface up to about 10 km in altitude, although this height varies with latitude. Almost all weather takes place in the troposphere. Everest, the highest mountain on Earth, is only 8. Temperatures decrease with altitude in the troposphere. As warm air rises, it cools, falling back to Earth.
This process, known as convection, means there are huge air movements that mix the troposphere very efficiently. Virtually all human activities occur in the troposphere. Everest, the tallest mountain on the planet, is only about 5. 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.
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