Ozone Layer: Composition and Formation

Study Notes

The ozone layer is a region in the stratosphere (15-30 km above Earth's surface) where ozone (O₃) is concentrated.
Ozone is a molecule composed of three oxygen atoms (O₂ + O → O₃).
The ozone layer contains approximately 90% of the atmosphere's ozone.

Ozone is formed through the interaction of ultraviolet (UV) radiation and oxygen molecules (O₂) in the stratosphere.
UV radiation breaks down oxygen molecules, releasing individual oxygen atoms, which then combine with other oxygen molecules to form ozone.
Ozone is destroyed through various mechanisms, including:
- Ultraviolet radiation: breaks down ozone molecules into oxygen atoms and molecules.
- Chlorofluorocarbons (CFCs) and other halogenated gases: react with ozone, breaking it down into oxygen molecules and releasing chlorine or bromine atoms.
- Nitrogen oxides: react with ozone, breaking it down into oxygen molecules and releasing nitrogen dioxide.

The ozone layer acts as a shield, absorbing most of the sun's harmful UV-B radiation, protecting life on Earth from its detrimental effects.
Ozone layer depletion can lead to:
- Increased UV-B radiation reaching the Earth's surface, causing skin cancer, cataracts, and damage to crops and ecosystems.
- Disruption of marine food chains and ecosystems.

The ozone layer has been depleted due to the release of CFCs and other ozone-depleting substances into the atmosphere.
The Montreal Protocol (1987) aimed to reduce and phase out the production and consumption of ozone-depleting substances.
As a result, the ozone layer has started to recover, with some regions showing signs of improvement.

Ozone layer is a region in the stratosphere (15-30 km above Earth's surface) where ozone (O₃) is concentrated.
Ozone is composed of three oxygen atoms (O₂ + O → O₃).
The ozone layer contains approximately 90% of the atmosphere's ozone.

Ozone is formed through the interaction of UV radiation and oxygen molecules (O₂) in the stratosphere.
UV radiation breaks down oxygen molecules, releasing individual oxygen atoms, which then combine with other oxygen molecules to form ozone.
Ozone is destroyed through various mechanisms, including:
- UV radiation breaking down ozone molecules into oxygen atoms and molecules.
- CFCs and other halogenated gases reacting with ozone, breaking it down into oxygen molecules and releasing chlorine or bromine atoms.
- Nitrogen oxides reacting with ozone, breaking it down into oxygen molecules and releasing nitrogen dioxide.

The ozone layer acts as a shield, absorbing most of the sun's harmful UV-B radiation, protecting life on Earth from its detrimental effects.
Ozone layer depletion can lead to:
- Increased UV-B radiation reaching the Earth's surface, causing skin cancer, cataracts, and damage to crops and ecosystems.
- Disruption of marine food chains and ecosystems.

The ozone layer has been depleted due to the release of CFCs and other ozone-depleting substances into the atmosphere.
The Montreal Protocol (1987) aimed to reduce and phase out the production and consumption of ozone-depleting substances.
As a result, the ozone layer has started to recover, with some regions showing signs of improvement.