GE15

• Atmosphere


  The layered ocean of air that extends upward about 500 km, with the lowest 10-12 km being the troposphere where weather occurs
• Troposphere


  • The layer of air immediately adjacent to the Earth's surface where air circulates in great vertical and horizontal convection currents, constantly redistributing heat and moisture around the globe
  • Its depth ranges from about 18 km over the equator to about 8 km over the poles
  • Contains about 75 percent of the total mass of the atmosphere
  • Air temperature drops rapidly with increasing altitude, reaching about -60°C at the top
• Stratosphere


  • Extends from the tropopause up to about 50 km
  • Much more dilute than the troposphere
  • Has almost no water vapor and nearly 1,000 times more ozone
  • Ozone absorbs specific wavelengths of ultraviolet solar radiation, warming the atmosphere toward the top
• Mesosphere


  • The third layer of the atmosphere directly above the stratosphere and directly below the thermosphere
  • Temperature decreases as altitude increases
  • Begins at the top of the stratosphere and ends at the mesopause, the coldest part of the Earth's atmosphere with temperatures below -143 degrees Celsius
• Thermosphere


  • Begins at about 80 km
  • A region of highly ionized (electrically charged) gases, heated by a steady flow of high-energy solar and cosmic radiation
  • In the lower part, intense pulses of high-energy radiation cause electrically charged particles (ions) to glow
• Temperature


  A measure of thermal energy, which is the kinetic energy of atoms and molecules in a substance
• Water vapor content


  Varies from less than 1% to about 4% by volume, depending on air temperature, air pressure, and availability of water vapor from the surface
• Greenhouse effect


  • Naturally a good thing, warming the planet to its comfortable average of 15 degrees Celsius and keeping life on earth livable
  • The problem is, mankind's voracious burning of fossil fuels for energy is artificially amping up the natural greenhouse effect
• Weather


  A description of the physical conditions in the atmosphere (humidity, temperature, air pressure, wind, and precipitation) over short time scales
• Climate


  The average weather and usually refers to average weather conditions over long periods, at least seasons, but more often years or decades
• Historical Records


  • Paleo-proxy
  • Ice Cores
  • Tree Rings
  • Sediments
  • Corals
  • Carbon-14
• Paleo-proxy


  Proxy data refers to scientific data that are not strictly climatic but can be correlated with climate data, such as the temperature of the land or sea
• Ice Cores


  Polar ice caps and mountain glaciers have an accumulation record of snow that has been transformed into glacial ice over hundreds to thousands of years, containing small bubbles of air deposited at the time of the storm, allowing measurement of atmospheric gases like CO2 and CH4
• Tree Rings


  The growth of trees is influenced by climate, both temperature and precipitation, with wider rings indicating good growth conditions and narrower rings indicating poor conditions, providing a proxy record of climate variability over 10,000 years
• Sediments


  Biological material, including pollen from plants, is deposited on the land and stored for very long periods in the lake, bog, and pond sediments and, once transported downstream to the coast, in the oceans, allowing study of past climates
• Corals


  Have hard skeletons composed of calcium carbonate, which contains isotopes of oxygen and trace metals that have been used to determine the temperature of the water in which the coral grew, revealing the chronology of climate change
• Carbon-14


  Radioactive carbon-14 is produced in the upper atmosphere by the collision of cosmic rays and nitrogen-14, with the abundance of cosmic rays varying with the number of sunspots, providing a measure of solar activity and climate change