The Ozone Shield 13.2
The Ozone Shield Ozone is a layer of the stratosphere that absorbs UV light from the sun (like sunscreen).
Chemicals That Cause Ozone Depletion CFC’s = chlorofluorocarbons When these break apart in the ozone, they destroy parts of it.
thinning of ozone during spring over the north and south poles caused by cold temperatures and CFC’s
The Ozone Hole (credit: NASA) 2005 Ozone Layer Hole
How Does the Ozone Hole Form?
How Does the Ozone Hole Form? During the dark polar winter, strong circulating winds over Antarctica, called the polar vortex, isolate cold air from surrounding warmer air. Air within the vortex is extremely cold.
Polar stratospheric clouds form at high altitudes. composed of water vapor and nitric acid
On the surfaces of polar stratospheric clouds, the products of CFCs are converted to molecular chlorine.
When sunlight returns to the South Pole in the spring, molecular chlorine is split into two chlorine atoms by UV radiation. The chlorine atoms rapidly destroy ozone.
Ozone from pollution may stay in the troposphere and react with other chemicals.
Effects of Ozone Thinning on Humans UV light damages DNA Effects of Ozone Thinning on Humans
Causes: increase in skin cancer
Premature aging of skin
Cataracts – clouding of the lens
Effects of Ozone Thinning of Animals and Plants
Kills phytoplankton and disrupts food chain
Kills amphibian eggs
Interferes with photosynthesis in plants
Protecting the Ozone Layer 1987 – Montreal Protocol Limits the use of CFCs
Review – The Ozone Shield What is the ozone layer and what is its function? What is ozone made up of? What are CFC’s? How do CFCs affect ozone? What is the ozone hole? What is a polar vortex? Explain how the ozone hole forms? Name 3 ways ozone thinning affects humans. Name 3 ways ozone thinning affects plants and animals. How are we protecting the ozone today?
Chemicals That Cause Ozone Depletion CFC’s chlorofluorocarbons When these break apart in the ozone they destroy parts of it. Ozone Hole: thinning of ozone during spring over the north & south poles. (caused by cold temperatures + CFC’s) 4. Problems: damage to plant & animal life
How Does the Ozone Hole Form? You may be thinking, “If ozone is also being produced as air pollution, why does this ozone not repair the ozone hole in the stratosphere?” The answer is that ozone is very chemically reactive. Ozone produced by pollution breaks down or combines with other substances in the troposphere long before it can reach the stratosphere to replace ozone that is being destroyed.
How Does the Ozone Hole Form? When sunlight returns to the South Pole in the spring, molecular chlorine is split into two chlorine atoms by UV radiation. The chlorine atoms rapidly destroy ozone. The destruction of ozone causes a thin spot, or ozone hole, which lasts for several months.