Stratospheric Ozone Depletion Flashcards
Describe the structure and thermal patterns of Earth’s atmosphere, and explain where the ozone layer is located
Troposphere: This is the layer closest to the Earth’s surface, extending from the surface to an altitude of approximately 7-20 kilometers. The troposphere is where weather occurs, and it contains most of the Earth’s atmospheric gases.
Stratosphere: Found above the troposphere, about 20 to 50 kilometers above the Earth’s surface.
Ozone Layer Location: Primarily situated within the stratosphere. It is most concentrated between approximately 30 and 35 kilometers above the Earth’s surface. This region is known as the “ozone layer.”
Describe the role of stratospheric ozone in the atmosphere
Filters out harmful ultraviolet (UV) radiation from the sun.
Explain how the ‘hole’ in the ozone layer was first discovered, and recognize how ongoing research monitors ozone levels
The “hole” in the ozone layer was first discovered through scientific research. Ongoing research monitors ozone levels using instruments that measure the total amount of ozone in Dobson Units (DU). Areas with values less than 220 DU are considered to have experienced severe ozone destruction. Researchers noticed a hole in ozone in Antarctica each spring
Explain the three conditions needed to enable ozone destruction
UV radiation, extremely low temperatures, and a surface for the ozone-destruction process.
Describe the basic chemistry of how stratospheric ozone is created and destroyed
Ozone is created when high-energy ultraviolet (UV) radiation from the sun breaks apart molecular oxygen (O2). An oxygen atom then combines with an oxygen molecule (O2) to form ozone (O3). Ozone is destroyed when ODSs release chlorine or bromine atoms in the stratosphere, which then react with ozone molecules, breaking them down.
Identify the control variable and planetary boundary for stratospheric ozone depletion
The control variable for stratospheric ozone depletion is the concentration of stratospheric ozone measured in Dobson Units (DU). The planetary boundary for stratospheric ozone depletion is set at maintaining less than a 5% reduction from the preindustrial level of 290 DU.
State the main goal of the Montreal Protocol as well as why it was amended over time, and describe some of its outcomes
The main goal of the Montreal Protocol is to phase out the production and use of ODSs to protect the ozone layer. It was amended over time to include additional ODSs and to accelerate the phase-out schedules. Outcomes of the protocol include a significant reduction in the production of ODSs, contributing to the recovery of the ozone layer.
Reflect on the factors that made the Montreal Protocol an environmental policy success story
The Montreal Protocol is considered an environmental policy success story due to factors such as global cooperation, the participation of all countries, and the amendment to include new substances like hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). The protocol’s success is evidenced by the expected recovery of the ozone layer by the mid-21st century.
