The Ozone Layer

Describe the chlorine catalytic cycle?

Cl+O3=ClO ClO+O=Cl

In the 1980s, scientists discovered that the ozone layer was thinning in the lower stratosphere, with particularly dramatic ozone loss—known as the "ozone hole"—in the _______________________________

Antarctic spring (September and October). At the poles, CFCs attach to ice particles in clouds. When the sun comes out again in the polar spring, the ice particles melt, releasing the ozone-depleting molecules from the ice particle surfaces. Once released, these ozone-destroying molecules do their dirty work, breaking apart the molecular bonds in UV radiation-absorbing ozon

The ozone hole is especially large over___________

Antarctica.

polar vortices

During the continuously dark polar winter, the air inside the polar vortices becomes extremely cold, a necessary condition for polar stratospheric cloud formation.THE POLES BECOME VERY COLD

The chlorine catalytic cycle can______________

RE-OCCUR thousands of times!

How is the one destroyed ?

1)UV+CFC=>Cl 2)Cl+O3=>Cl and O2 STEP CONTINUES TO REPEAT UNTIL CFC decays

Where is smog ozone?

10% of the ozone is in the trophospherIe. It is found in the lower atmosphere (troposphere) and has nothing to do with the "ozone hole."e.

In which season is the Antarctic Ozone Hole especially?

Spring (Sep, Oct...in Antarctica)

ozone depletion is facilitated by the _________

polar vortex

Polar stratospheric clouds

reate the conditions for drastic ozone destruction, providing a surface for chlorine to change into ozone-destroying form. They generally last until the sun comes up in the spring.

Global warming leads to__________

stratospheric cooling, exacerbating the loss of ozone.

Besides CFCs what else contributes to ozone loss?

sulfur containing volcanic aerosols

Ozone Depletion:What are chlorofluorocarbons (CFCs)?

- Long-lived gases used as refrigerants and in other industrial applications.

How fast are CFCs declining?Why haven't we seen a return to conditions that existed before these chemicals were first introduced?

-CFCs are exceedingly long lasting in the atmosphere -Once emitted, they will reside in the atmosphere for about 60 to 200 years -In short, they are STILL contributing to stratospheric ozone depletion!

The term 'ozone hole' refers to_______________

the depletion of the protective ozone layer in the upper atmosphere (stratosphere) over Earth's polar regions. People, plants, and animals living under the ozone hole are harmed by the solar radiation now reaching the Earth's surface—where it causes health problems, from eye damage to skin cancer.polar vortices

Why is there a slow decline of CFCs since protocol?

they have a long half life

Does the ozone hole cause global warming?

-The ozone hole doesn't contribute to global warming. • Yet CFCs are effective greenhouse gases. • Global warming cools the stratosphere, which can enhance the ozone loss (see what happened in Sep 2015). • The ozone hole "might" affect winds and cloud formation over Antarctica, possibly impacting the "regional" climate.

What happens after CFCs are emitted, and reach the ozone layer?

1)CFCs are emitted, and reach the ozone layer 2)CFCs are broken down by the sun's UV rays, and chlorine atoms are released into the ozone layer, thus causing a chain resolution of the ozone layer 3) harmful ultraviolet rays reaing the Earth increase.

WHY does the ozone hole form over Antarctica, and WHY especially in this season?

1)Polar stratospheric clouds form in winter. 2)The presence of reactive chlorine (Cl) and bromine (Br) etc. form in the spring. Why? CFCs 3)The presence of light (UVC) splits bonds.

What happens when UV strikes CFCs?

A carbon-chlorine bond breaks, producing a chlorine (Cl) atom. The chlorine atom then reacts with an ozone (O3) molecule, breaking it apart and destroying the ozone.

Does global warming have an impact on the stratospheric ozone layer?

In other words, heat-trapping gases contribute to creating the cooling conditions in the atmosphere that lead to ozone depletion. Greenhouse gases absorb heat at relatively low altitudes and warm the surface--but they have the opposite effect in higher altitudes because they prevent heat from rising. In a cooler stratosphere, ozone loss creates a cooling effect that results in further ozone depletion. UV radiation releases heat into the stratosphere when it reacts with ozone. With less ozone there is less heat released, amplifying the cooling in the lower stratosphere, and enhancing the formation of ozone-depleting polar stratospheric clouds, especially near the South Pole.

The Montreal Protocol was__________

The Montreal Protocol was fairly successful.

WHY? Didn't the protocol work?

The Montreal Protocol worked, and the scientists were right about CFCs. • However, it was due to unusually COLD temperatures in the stratosphere. • 2015 was a year when an El Niño occurred, and global warming caused a stratospheric cooling effect.

Formation of the Ozone Laye in the stratosphere: Chapman Cycle

Use UV to split oxygen into two free atomic following reactions: oxygen radicals, and then make Ozone. 1)O2 + ultraviolet light->O + O -High energy UV radiation strikes an oxygen molecule..... and causes it to split into two free oxygen atoms 2)O + O2->O3 -The free oxygen atoms collide with molecules of oxygen....to form ozone molecules

In 2015, Antarctic ozone hole _______________

expanded to near-record size