NOTES
Links to summaries of key issues for each topic
VISUALS
Links to images employed in lectures on a topic-by-topic basis
TEXT
Link to chapter outlines at online learning center at McGraw Hill.
NOTES
Links to summaries of key issues for each topic
|
|
The Ocean and Atmosphere
(contd.)
|
Notes on Topic:
The notes represent summaries
of key issues for each topic
They emphasize the terminology used to
describe the various phenomena.
| 3. The Atmosphere in Motion: |
| Learning Objectives: |
- Understanding how the Earth's rotation controls wind patterns
- Recognition of the characteristics of atmosphere circulation
- Appreciation of the coupling between seasonal winds and climate features
|
| Winds on a Rotating Earth, Coriolis Effect: |
- Winds on a Non-rotating Earth:
- hemispherical atmospheric circulation system
- large cells in each hemisphere
- warm air rises at equator, cools with water vapor, condensing as rain
- dry air, cooled than sinks at poles
- surface winds blow from poles to equator
- The effects of rotation:
- equator moves eastward at 1700km/hr
- speed decreases with increasing latitude:
- creates deflection relative to Earth's surface:
- right in N. hemisphere
- left in S. hemisphere
- Coriolis Effect
- air affected more by centrifugal force than Earth's surface.
|
| Wind Bands: |
- Six-celled atmospheric circulation
- deflection of air by Coriolis effect
- equatorial warm air rises, sinks at ~30°N
- at 30°N some moves back towards equator as trade winds
- NE in N. hemisphere
- SE in S. hemisphere (directions from which they blow)
- trade winds converge at equator
- intertropical convergence zone (ITCZ).
- at 30°N remaining air flows towards poles as westerlies
- westerlies meet colder, dense air flowing from poles towards equator
- these air masses converge at Polar (Antarctic) Front
- Jet stream:
- narrow band of strong winds at polar front
- winds vary seasonally, as cells migrate
- Winds influence climate (long-term averaged weather)
- mid-latitudes:
- low rainfall, high evaporation
- light variable winds (horse latitudes)
- high atmospheric pressure;
- equatorial regions:
- high rainfall, cloudiness
- light variable winds (doldrums)
- low atmospheric pressure.
- Cells called:
- Hadley (0 - 30°), Ferrel (30 - 60°) and Polar (60 - 90°)
|
| Seasonal Variability in Winds: |
- Seasonal changes:
- caused by differential solar heating of ocean and land
- product of high heat capacity of water
- Summer:
- low pressure areas over land caused by rising air
- high pressure over ocean
- Winter produces the opposite effect
- Monsoons
- regional seasonal changes in winds
- a result of continent configurations
- Summer:
- warming land with rising air draws cooler, moist air from ocean
- yielding monsoon rains
- Winter:
- winds reverse, cool continental air is drawn towards ocean
- dry weather.
- Sea breezes:
- warm land air rises, replaced by cool sea air
- land breezes: warm sea air rises, replaced by cool land air
- occur daily
|
| Effects and Feature of Winds: |
- Topographic effect of mountains on surface winds
- winds rise, cool, leading to condensation of water vapor
- precipitation on windward side of islands
- dry air on leeward side (rain shadow)
- Jet Streams:
- high speed winds of upper troposphere
- polar jet streams at 60°N and 60°S; westerlies
- sub-tropical jet streams at 30°N and 30°S
- greatest oscillation in winter
|
Department of Geological Sciences,
1001 E. Tenth Street, Bloomington, IN 47405-1403
Phone: (812) 855-5582 Last updated: 7 October 2000
Comments: simon@indiana.edu
Copyright
2000, The Trustees of Indiana University
|
