ESS SL topic 6.4 Stratospheric Ozone (new syllabus)

Electromagnetic radiation (6.4.1)

Energy transmitted through space as waves traveling at light speed. Solar energy reaching Earth including visible light and infrared.

Wavelength (6.4.1)

Distance between consecutive peaks or troughs in a wave. Blue light measures 450 nanometers; red light 700 nanometers.

Frequency (6.4.1)

Number of wave cycles passing a point per second. FM radio operates at 100 megahertz frequency.

Ultraviolet (UV) radiation (6.4.2)

High-energy electromagnetic waves shorter than visible light wavelengths. Solar radiation causing skin tanning and sunburn.

UVA (6.4.2)

Longest UV wavelengths (315-400 nm) penetrating skin deeply. Radiation causing premature skin aging and wrinkles.

UVB (6.4.2)

Medium UV wavelengths (280-315 nm) causing direct DNA damage. Primary radiation responsible for sunburn and skin cancer.

UVC (6.4.2)

Shortest UV wavelengths (100-280 nm) with highest energy. Germicidal radiation completely absorbed by stratospheric ozone.

Stratospheric ozone (6.4.3)

Three-oxygen molecules concentrated 15-35 kilometers above Earth's surface. Ozone layer protecting ecosystems above Nairobi, Kenya.

Photosynthesis (6.4.4)

Process converting light energy into chemical energy in organisms. Phytoplankton producing oxygen in Antarctic Southern Ocean.

DNA mutation (6.4.4)

Permanent alteration in genetic material's chemical structure. Thymine dimer formation from excessive UV exposure.

Cancer (6.4.4)

Uncontrolled cell growth resulting from genetic damage. Melanoma skin cancer in Australian coastal populations.

Sunburn (6.4.4)

Inflammatory skin response to excessive UV radiation exposure. Redness and pain after midday sun exposure.

Cataracts (6.4.4)

Clouding of eye lens reducing vision clarity. Vision impairment in elderly Chilean fishermen from UV.

Phytoplankton (6.4.4)

Microscopic photosynthetic organisms forming oceanic food web base. Diatoms in Southern Ocean supporting krill populations.

Steady state equilibrium (6.4.5)

Balanced condition where formation and breakdown rates equal. Natural ozone maintained at 300 Dobson Units.

Ozone formation (6.4.5)

Creation of three-oxygen molecules from oxygen gas. UV radiation splitting O₂ in tropical stratosphere.

Ozone destruction (6.4.5)

Breakdown of three-oxygen molecules into oxygen gas. Natural breakdown through UV absorption or chemical reactions.

Ozone-depleting substances (ODSs) (6.4.6)

Human-made chemicals accelerating stratospheric ozone breakdown. CFC-12 from refrigerators and air conditioners.

Ozone depletion (6.4.7)

Reduction in stratospheric ozone concentration below natural levels. Antarctic ozone hole reaching 25 million square kilometers.

Ozone hole (6.4.7)

Region with ozone concentrations below 220 Dobson Units. Antarctic stratosphere during September-November spring period.

Polar regions (6.4.7)

High-latitude areas near Earth's geographic poles. Antarctica and Arctic regions above 60 degrees latitude.

Montreal Protocol (6.4.8)

1987 international agreement phasing out ozone-depleting chemicals. 198 countries committed to eliminating CFC production.

Chlorofluorocarbons (CFCs) (6.4.8)

Synthetic compounds containing carbon, chlorine, and fluorine atoms. CFC-11 formerly used in aerosol spray cans.

International treaty (6.4.8)

Legally binding agreement between multiple sovereign nations. Paris Agreement on climate change with 195 signatories.

Planetary boundary (6.4.9)

Threshold beyond which Earth system changes become irreversible. Stratospheric ozone depletion limit of 5% reduction globally.