How Does Weather Work?

Weather as a Feedback Loop

• Unequal distribution of radiation due to earth axis tilt is the ultimate driver of the weather.

• Heat, energy flow is generally from the equatorial regions to the polar regions.

• Rotation of the earth sets up large scale circulation cells called Hadley Cells As well as Rossby Waves To learn more about this go here

• Ocean currents and temperature influence the temperature of the air and hence its capacity to hold moisture

• Large Scale climate is set up by the constant exchange of moisture and energy between the ocean and the circulating atmosphere. These determines large scale pattern of High and Low pressure areas

• Pacific Coast Pacific Maritime Climate Cold Current, strong ON shore flow of dry air in the Summer no humidity!

• East Coast Warm current, lots of moisture, Bermuda High brings it a shore -summers suck!
  • Let's see the Movie which shows the seasonal evolution of these currents

Climate Change:

• Periodic Ice Ages ---> Glacial-Interglacial Periods
  • Major Period: ---> 100,000 years; 9 degree F decrease
  • Minor Period: ---> 12,000 years; 5 degree F decrease
  • Smaller Periods??: ---> 1,000 years; 3 degree F decrease

  We currently are nearing the end of a small, minor interglacial period

• Major Ice Ages: Most of the Planet is Covered
• Minor Ice Ages: 40 Latitude and Above
• Little Ice Age: (1000-1850 AD; Irish Potato Famine; Nisqually Glacier)

Effects of Ice Ages

• Changes sea level by 100 meters exposes continental shelfs
• changes continental shelf composition due to increased deposition during melt
• changes hydrological cycle through less evaporation
• changes landscape Great Lakes; Seattle; Stoss and Lee
• Changes drainage patterns
• changes topsoil characteristics
• massive flooding episodes --> Eastern Washington

Causes of Ice Ages --> needs to be PERIODIC!

• Solar Cycle --> no evidence
• Volcanic Dust in Atmosphere --> why periodic?
• CO Cycle --> why periodic? --> factor 2 reduction causes 7 F drop
• Increased precipitation at poles due to changing orientation of continental land masses
• Changes in mean temperatures of ocean currents --> what mechanism?

The most Probable Cause:

• Orbital Variations of the Earth!

• Eccentricity variation 90,000 years 5 variation around mean value. This is due to Jupiter.
• Change of tilt of axis 24,000 years

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The Electronic Universe Project

e-mail: nuts@moo.uoregon.edu