Green Glossary: Ozone Layer

The ozone layer has swiftly become something we all talk about but don't necessarily understand fully. So, let's see if Jane McGrath from HowStuffWorks can help. "The ozone layer gets its name from ozone gas, an allotrope, or form, of the element oxygen," writes McGrath. "Ozone gas has become so synonymous with the ozone layer that people now refer to the layer as 'the ozone'."

However, the ozone layer isn't just ozone gas. "Oxygen gas, another allotrope of oxygen, is abundant in the ozone layer, as well," McGrath adds. "Oxygen gas is essential for the creation of ozone gas, and it absorbs ultraviolet light, preventing that light from reaching the earth's surface. The ozone layer forms naturally in the stratosphere, where ozone and oxygen gas are always converting into each other." McGrath likens this to a continual "reapplying" of the earth's "sunscreen."

But what about the infamous hole in the ozone layer? Jonathan Shanklin of the British Antarctic Survey explains how humans have "introduced chemicals into the atmosphere that are capable of destroying ozone through photochemical processes." These processes have occurred mostly over the past half-century thanks to ozone depleting substances like chloro-fluoro-carbons (CFCs), halons (bromo-fluoro-carbons), and methyl bromide. "In certain circumstances," Shanklin writes, "the chlorine or bromine from these substances can react with ozone to turn it back into oxygen. In most parts of the world the reactions are very slow and there is little damage to the ozone layer, however over the Antarctic a dramatic hole opens in the ozone layer every spring and fills in again by mid-summer. This is created by the unusual atmospheric conditions that exist during the Antarctic winter."

Can you say uh-oh?

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