Wednesday, February 1, 2012

Chapter 18-19 Notes

18.1 Water in the atmosphere,

Key concepts
  • Water vapor is the most important gas in the atmosphere for understanding atmospheric processes.
  • The process of changing state requires that energy is transferred into the form of heat.
  • When saturated, warm air contains more water vapor than cold air.
  • Relative humidity is a ratio of the airs actual water vapor content compared to the amount of water vapor needed for saturation at the current temperature & pressure.
  • When the water vapor content of air remains constant lowering air temp. causes an increase in relative humidity and raising air causes a decrease in relative humidity.
18.2 Cloud Formation,
  • When air is allowed to expand, it cools, and when its compressed it warms up.
  • Four mechanisms that can cause air to rise are orthographic lifting, frontal wedging, convergence, & localized connective lifting.
  • Stable air tends to remain still while unstable air rises.
  • For any kind of condensation to occur, the air must be saturated.
19.1 Understanding Air Pressure
  • Air pressure is exerted in all directions. up, down, and sideways. The air pressure pushing down on the object exactly balances the air pressure pushing up on it.
  • Wind is the result of horizontal differences in air pressure. Air flows from areas of higher to areas of lower pressure.
  • Three factors combine to control wind: pressure differences, the Coriolis's effect, & friction.
  • The Coriolis effect depicts how the rotation of the earth offsets the winds destination by 15 degrees.
19.2 Regional Wind Systems
  • The local winds are caused by topographic effects or by variations in surface composition -land & water- in the immediate area.
  • In the united states, the westerlies consistently move weather from west to east across the country.
  • When surface temps in the east pacific are colder than average, a La Nina event is triggered that has a distinctive set of weather patterns.

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