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Creating an
Earth System II

Creating an Earth System II:

Learning about the Ozone

Reviewing the Earth's Atmosphere - The Radiation Medium

Origin of the Atmosphere

  • Impacts (e.g. comets) that brought water, CO2, and other gases to Earth in a frozen form.

  • Internal sources that were vented during volcanic eruptions.

Structure of the Atmosphere

The atmosphere consists of subdivisions according to temperature:

Troposphere: The lowest layer, where humans live and weather happens. Temperature drops roughly 3.5°F for each 1000' of elevation gain.

Stratosphere: Home of the ozone layer, which absorbs UV radiation (heating this layer a bit).

Mesosphere & thermosphere

The Ionosphere contains plasma that absorbs most wavelengths of radiation. Thus these wavelengths are very hard to study from Earth itself.

images courtesy www.nasa.gov

The Ozone Layer

The Sun's UV radiation is absorbed by the ozone layer. Ozone consists of oxygen atoms bonded in threes (O3); we breathe oxygen that's bonded in pairs, or O2. Ozone forms in the mid-stratosphere.

Without the ozone layer, the Earth's surface would be sterilized by UV radiation. The breakdown of the ozone layer increases skin cancer and cataracts in humans, impairs immune systems of all animals (including humans), and interferes with phytoplankton productivity in the oceans.

Humans have impacted the ozone layer: Chlorofluorocarbons (CFCs) used for refrigeration, cleaning solvents, and aerosol sprays since the 1950s help destroy ozone. Ozone became strongly depleted over the Earth's polar regions in the later part of the 20th century.

Video: Ozone

This video Resource: Sun Splash Ozone

This NASA video explains ozone depletion using computer graphics and animation. An educational narrative explains how stratospheric ozone protects us from UV radiation and demonstrates how chlorofluorocarbons cause destruction of the Earth's ozone layer. The video is appropriate for grades 5-8, 7 minutes in length, closed-captioned, and sells for $10.00. It is available from NASA CORE: Visit NASA CORE or e-mail: nasaco@leeca.org.

Activities:

  1. Whole Body Ozone Chemistry an activity that illustrates the formation and destruction of ozone molecules.

  2. The Ultraviolet Project Chemistry an activity that uses UV sensitive beads to illustrate the effects of the Sun's ultraviolet rays.

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