The Ozone Layer

The Ozone Layer

OZONE LAYER

• Area in the stratosphere where ozone is highly concentrated.

  
  

• Absorbs most of the UV (ultraviolet) light from the sun

  
  

• "is like sunscreen for the Earth"

Ozone

• a molecule made of three oxygen atoms

• a colorless gas

Two Types of Ozone

• Good Ozone - ozone in the stratosphere that protects human health and the environment

• Bad Ozone - ground-level ozone which is a respiratory irritant (emissions mixed with heat and sunlight)

Multiple Choice

The role of the Ozone layer is to...

• protect Earth from infrared radiation

• protect Earth from ultraviolet radiation

• protect Earth from gamma radiation

Chemicals that cause Ozone Depletion

depletion - reduction in the number or quantity of something

Chlorofluorocarbons (CFCs)

- used as coolants

- chemically stable at Earth's surface

- break apart in the stratosphere and destroy the ozone layer

Multiple Choice

Depletion of ozone layer is caused by...

• methane

• UV rays

• gamma rays

• chlorofluorocarbons

The Ozone Hole

formed when CFCs are converted to chlorine, which breaks up ozone

Antarctic Ozone Hole (Sept 20, 2020)

The severe depletion of the Antarctic ozone layer known as "the ozone hole" occurs because of the special atmospheric and chemical conditions that exist there and nowhere else on the globe.s

Multiple Choice

The hole in the ozone layer is located..

• over Antarctica

• over the Arctic

Effects of Thinning Ozone on Humans, Plants, and Animals

• Humans - damages DNA, causes skin cancer

• Plants - interferes with photosynthesis

• Animals - kills eggs (off springs)

Multiple Choice

UV rays can...

• damage the DNA of organisms

• damage eggs

• cause cancer

• all of these

Protecting the Ozone Layer

• 1985 - Vienna Convention for the Protection of the Ozone Layer

• 1987 - Montreal Protocol - nations agreed to sharply limit their production of CFCs

• 1992 - Copenhagen, Denmark - developed countries agreed to eliminate most CFCs by 1995

  
  

• US pledged to ban all substances that pose significant danger to ozone by 2000

Still a Battle

• CFC molecules remain active in the stratosphere for 60 to 120 years

• CFCs released 30 years ago are still destroying the ozone today

• CFCs released from leaky air conditions still exist

• Many years will be needed before the ozone layer completely recovers.

HCFC (hydrochlorofluorocarbon) - a fluorocarbon that is replacing (CFC) chlorofluorocarbon as a refrigerant and propellant in aerosol cans; considered to be somewhat less destructive to the atmosphere

Ozone Depletion and Climate Change

• Global warming (climate change) and ozone layer depletion are two different problems.

• Global warming is caused by the "greenhouse effect", while ozone depletion is caused by "ultraviolet (UV) rays"

Climate change and ozone depletion are both examples of changes to the planet’s environment caused by human civilization releasing substances into the atmosphere.

They also both have consequences that could be harmful on a global scale.