09circulationpatterns

GEOGRAPHY 101 Front Page
CIRCULATION PATTERNS
MATERIALS NEEDED FOR CLASS:
Daily Lesson Plans. H.K.C--Take roll and announcements. TEXT: Essential of Physical Geography: 6th Edition, Robert E. Gabler, Robert J. Sager, Daniel L. Wise, and James Peterson. Saunders College Publishing, Harcourt Brace College Publishers 1999. Rand McNally GOODE's WORLD ATLAS
GENERAL OUTLINE:
VI. Circulation Patterns
A. To investigate the General Circulation of the Atmosphere, the Global Surface Wind Systems.
B. To theorize about the Idealized Model of Atmospheric Circulation.
C. To describe the Major Wind Systems--The Condition Within Latitudinal Zones.
D. To examine the Effects of Seasonal Migration on Wind Patterns and the Longitudinal Difference in the Winds.
E. To describe the General Circulation of the Ocean Currents and to discuss El Nino and the Southern Oscillation.
F. To identify Sub global Surface Wind Systems--Localized Wind Systems.
G. To point out the significance of Upper Wind Patterns.
THE MATERIAL IN THIS OUTLINE COVERS PAGES 130--151 BUT THERE IS MATERIAL NOT IN YOUR BOOK--KNOW IT--KNOW IT--KNOW IT

ANTICIPATORY SET

What starts the process which moves the winds? What is El Nino and the Southern Oscillation?

Where are the Global Surface Wind Systems and how do they work? What are Sub-Global Wind Systems?

How does the General Circulation of the Atmosphere act as a thermostats for the entire planet? How are the Modifications of the General Circulation important to places like India?

How many Wind belts are there? What are the Localized Wind Systems?

Where are the Ocean Currents and what do they do? What are the Upper Air Winds?

BEHAVIORAL OBJECTIVES These are the fast ones.

To trace the General Circulation of the Atmosphere in theory. To point out the connection between pressure systems and wind systems.

To evaluate the Trade Winds. To identity polar easterlies, westerlies, and trade winds. (Each hemisphere has matching systems.)

To locate the Intertropical Convergence Zone also called the Doldrums. To investigate El Nino and the Southern Oscillation.

To classify and locate Subtropical Highs. To sketch El Nino and Global Weather and the Atlantic Cycle.

To describe the Westerlies. To evaluate the importance of Monsoons

To compare and contrast the polar front jet stream and subtropical jet stream. To outline Localized Wind Systems.

To identity Polar Winds and Polar Front. To identity Land and Sea Breezes, Valley and Mountain Breezes, and Drainage Winds or Katabatic Winds.

To investigate Seasonal Variations in Location To identify the bora, mistral, and the Taku.

To outline Ocean Currents and their general pattern. To review Foehn winds like

To list the oceans of the World. Chinook and Santa Ana Winds .

To identify gyres. To describe Upper Air Winds like the Jet Streams.

To discuss the influences of Cold and Currents on, fishing climate, navigation and the Land masses To identify the polar jet stream, subtropical jet stream and Rossby waves.

INSTRUCTIONAL INPUT
Content Methods:Lecture andClassroomdiscussion
OVERVIEW:
The winds are created indirectly by unequal radiation of Sun producing differences in temperature, which create pressure patterns, the invisible hand for weather, which moves the winds. You probably have figured out that everything is connected. This is why it looks like I'm repeating myself so often. The circulation patterns of air and water, point out the connections that Chapter One tried to stress. The theme of this chapter is the General Circulation of the Atmosphere (the winds) and its counterpart the circulation of the oceans. Both systems act as a thermostat in the transfer of heat of the entire planet.
I GLOBAL SURFACE WIND SYSTEMS
A. It is the pressure systems which move the winds and convey heat and water across the planet. The circulation of air in the atmosphere can be thought of as a thermostat for longitudinal and latitudinal heat transfer. Like many things in geography a model can be used to display the movement of the winds. In this model the continents and the seasons are ignored and the Earth has only a uniform (homogeneous) surface.
THE IDEALIZED MODEL OF ATMOSPHERIC CIRCULATION
B. The Atmosphere is very energetic and is in constant motion. The patterns in the atmosphere displays several major semipermanent conditions of wind and pressure. The global winds are moved by these pressure cells (Take a look Figure 6.1 on p. 135 and compare the pressure systems marked by arrows and the zonal wind system.) The properties of convergence (rising air) and divergence (falling air) are critical in comprehending atmospheric circulation. It should be remembered that the pressure gradient causes, surface winds move from zones of high pressure to zones of low pressure systems, (It could be said they flow down hill,) surface air diverges from zones of high pressure and converges on areas of low pressure.
C. If the Earth did not rotate it would be a simple pattern of north-south or south-north air flows from the cooler air at the poles going to the Equator and warm air at the Equator going to the poles. The Earth does spin, and has a diverse surface.
D. The model factors differences in heating and cooling, the rotation of the Earth, and other atmospheric conditions. Wind does not flow in a linear north-south direction, but because of the Coriolis Effect is defected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
POLAR EASTERLIES
E. The model of Atmospheric Circulation has six wind zones, compared to the seven zones of air pressure. (Take a look at Figure 6.1 on p. 135 and count up or down from the poles) Two wind systems, one in each hemisphere, the winds drift down from the polar high pressure cells (down the pressure gradient) to subpolar lows. Depending on what hemisphere, they are deflected to the right or the left and form polar easterlies in each hemisphere.
SUB-TROPICAL HIGHS--GREAT WIND MACHINES
WESTERLIES AND TRADES
F. The Sub-Tropical Highs (STH's) can be called great wind machines because the four wind systems, two in the Northern Hemisphere and two in the Southern, are formed from divergent winds of the Sub-Tropical highs. The wind flow is in a poleward direction in both hemispheres, toward the subpolar lows. Since the prevalent direction is from the west, the winds of the upper and midlatitudes are called westerlies. Winds coming off the sub-tropical highs toward the equator are called the trade winds, which flow in an easterly direction. As a result of the Coriolis effect, they blow from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere.
LOCATIONS OR MAJOR WIND AND PRESSURE SYSTEMS
G. Despite a complicated interrelated system certain patterns for pressure and wind do exist from the poles to the equator. From the poles to the equator the pattern is:
(Wind Systems are in bold)

1. Polar highs 2. Polar Easterlies 3. Subpolar lows 4. Westerlies

5. Subtropical highs 6. Trade Winds 7. Intertropical Convergence Zones.

II THE TRADE WINDS
A. Since Atmospheric circulation has no great beginning or ending, a description can begin almost anywhere. The Sub-Tropical highs (STHs) of the five ocean basins are a good place to start. It can be said that they are the "source" of four major surface wind systems of the planet. Spinning off from the equatorward sides, either north or south of the STH's are the trade winds. The Trade Winds blanket the planet between the latitudes 5š and 25š , but are broken up over the continents. Since most of the planet in the tropics is oceanic the trades are more important than any other wind system.
DIRECTION OF TRADE WINDS
B. Trades Winds are primary easterly winds, they blow from east to west. Sometimes they are called tropical easterlies. Remember Winds are defined from the direction which they blow. Latitude plays a part in the general pattern, in the Northern Hemisphere, they generally come from the Northeast in a clockwise direction. In the Southern Hemisphere they come from the Southeast in a counterclockwise direction.
C. The Trade Winds are the most dependable of all wind systems. They are generally unvarying in direction and speed, both during the night and day, summer and winter. They do shift a few degrees of latitude north or south because of the seasons. It is not surprising that during the "Age of Discovery" they were christened the Trade Winds. They were the fastest way to go from Europe to the New World. They were also used when the first Europeans sailed in the Pacific. (What group of people sailed the Pacific centuries before the Europeans and made very long voyages knew about the trades and the westerlies?)
TOPOGRAPHIC BARRIERS
D. These winds are a warming and drying wind and evaporate vast amounts of water from the tropical seas. They carry this water which has the capacity for great amounts of precipitation. This is not realized until the winds meet some topographic barriers or some sort of pressure system. Very low islands in the trade wind zones have little rainfall and are called desert islands but if islands in the trade wind area have the slightest increase in elevation then rainfall can be extensive. An example is the windward slopes of Hawaii, which moderate temperatures even though Hawaii is south of the Tropic of Cancer. (What pressure system and related phenomenon begins in late Summer to early Fall, and how did it effect American History in the late summer of 1781? )
III DOLDRUMS SUBTROPICAL HIGHS
AND WESTERLIES
DOLDRUMS--INTERTROPICAL CONVERGENCE ZONE
A. The doldrums are a zone of low pressure and calm weather located near the equator.Trade Winds from the north and south meet near the equator in a belt called the doldrums. This is an equatorial trough or tropical low. This is an area of light, variable winds and calms. It is a narrow belt around the equator of rising air which pumps huge amounts of heat and water into the Atmosphere, remember the film. This heat and moisture moves towards the poles in one of the great circulation patterns of the Earth.
B. The location of Doldrums is about 5š N and 5š S and is also called the Intertropical Convergence Zone, ITC, and it has other names like equatorial front and intertropical fronts. The doldrums is a belt of convergence and weak horizontal air flow. (What is the name of the very long poem which describes being becalmed in the doldrums. You can look it up in the book on p. 136.)
SUBTROPICAL HIGHS
C. Located about 25š to 35š N and S latitude over each of the five ocean basins are extensive semipermanent high pressure cells called a subtropical high, STH. These cells are immense anticyclones and encompass an area on the average of about 2,000 miles.
D. In the center of each STH the weather is calm, clear, sunny and warm, but more important they are without wind. They are at the same latitudes as most of the major deserts of the world. This area of the world's oceans are also called the horse latitudes, in the 16th and 17th centuries sailing ships sometimes became becalmed and if they were carrying horses, they were jettisoned to save drinking water.
WESTERLIES--THE MAJOR WIND SYSTEM OF MIDLATITUDES
E. The Westerlies are a major wind belt which begin from the poleward fringes of the Subtropical STH's. The basic pattern is west to east between the latitudes 35š and 65š north and south, the Earth is narrower at these latitudes. The Westerlies are less expansive than the trades, but they do blanket a great deal of the planet at midlatitudes. Most of the United States, excluding Florida, Hawaii, and Alaska, are blanketed by the Westerlies.
F. The Westerlies near the surface and are not as reliable as the trades. Sometimes they can come from any direction and are equivalent to the currents and eddies of a river. These differences in the western air flow are caused by surface friction, topographic barriers, and the shifting of the pressure systems. The Westerlies are tied to stormy weather. (There is more to it than just the prevailing wind pattern, but this will come later in the notes.)
POLAR WINDS OR POLAR EASTERLIES AND
G. Polar Winds or Polar Easterlies are another world-wide wind system located between the polar highs around 60š latitude and they are cold and dry, but are very variable. There are few weather stations in the polar regions so satellites are used.
POLAR FRONT--
H. Another element of the atmospheric circulatory system is in areas of low pressure at 50š to 60š latitude in both hemispheres. In the Northern Hemisphere the subpolar lows are the Aleutian low and the Icelandic low. The polar front marks the location where westerlies and polar easterlies meet. When cold winds of the polar easterlies and warmer winds of the westerlies meet, fronts can develop. The narrow boundary between the warm air masses of the westerlies and the cold air masses is the polar front. Fronts are narrow bands of changing weather (storms) between two different air masses. Many storms which track in the midlatitudes are born at polar front. (We are not there yet but I've mention this in passing before if you want to take a look at Figure 8.1 on p. 186 you'll get a better idea on what I've been trying to tell you.)
THE EFFECTS OF SEASONAL MIGRATION
D. As could be expected there are many differences to the general circulation pattern. The seven surface factors, check the list of p. 4, move northwards during summer in the Northern Hemisphere. This is the latitudinal shift of summer and the opposite happens in winter with a shift of winter southwards. In the polar regions and the tropics show little change of weather. In some areas that have Mediterranean climates like Southern California the change is from warm, rainless summers, to frequent storms in winter but this is not a vast change.
IV OCEAN CURRENTS
REVIEW: MECHANISMS OF HEAT TRANSFER
A. I've used the term "Mechanisms of Heat Transfer" or "Earth's Weather Machine" the terms mean the same and it is the process which is important. Both the air and the waters of the Earth are moved in the same manner, by convection currents which move them from one place to another. These currents transfer heat between warm areas and cooler areas. If you know the basic process in one, you will know the basic process in the other, only the details vary.
THE TWO SYSTEMS ATMOSPHERIC AND OCEANIC
B. Of the two great circulation systems, Atmospheric circulation is more important. Despite the many ways the wind blows, there is a worldwide framework. The pattern of Atmospheric circulation and Oceanic Circulation are interrelated and are mechanisms of heat transfer. The oceans have some problems that the atmosphere does not in heat transfer because of the location of the land masses. The example is warm Pacific Ocean water is hindered from entering the Arctic ocean by the Bering strait. Compare this with the most less restricted flow from the Arctic into the North Atlantic (Labrador Current .) The continents also block the free flow of oceanic currents except the circumpolar ocean current in the Southern Hemisphere, the West Wind Drift. (Take a look at Figure 6.5 on p. 139 and Table 6.1 on p. 140. No you do not need to know the list, but if a current is bold faced know that one.)
INFLUENCES ON CURRENTS
C. The circulation of water in the ocean are called currents. They can loosely be called rivers in the ocean. Major surface currents are set in motion by the winds but are so big that it takes months for them to respond. Most of the time they are mirror images of the wind conditions. Other factors like temperature salinity, tides, and wave action have some effect on ocean currents.It could be said that the oceans act as another thermostat for the entire planet. As you might have suspected all the world's great oceans are part of one system and are interconnected.
OCEANIC CIRCULATION --THE BASIC PATTERN
ELLIPTICAL SPIRAL--GYRES
D. However, because of the location of the continents and the pattern of atmospheric circulation it is handy to think of five ocean basins. The five basins are: The North and South Pacific, The North and South Atlantic, and the Indian. All show a parallel pattern, the pattern is a chain of great elliptical spirals and are elongated east to west. Except for the Indian Ocean they are located at about 30š of latitude, the Indian is centered at the Equator. The spirals are called gyres. In the Southern Hemisphere the currents run counterclockwise, while the currents in the Northern Hemisphere run clockwise. This effect is called the Coriolis Effect. The Coriolis Effect is mainly caused by the Earth's rotation.A rule of thumb surface currents do not cross the equator (Take a look at Figure 6.4 on p. 139 for the basic pattern)
WARM CURRENTS
E. In the Northern Hemisphere two warm currents the Gulf Stream and the Kuroshio are diverted to the right and move eastward across the ocean and become the North Atlantic Drift and the North Pacific Drift.(On tests I'll try to use both the Gulf Steam and North Atlantic Drift..) Some currents like the Gulf Stream/North Atlantic Drift warms Western Europe, the British Isles, and even keeps some ports in Norway ice free.
COLD CURRENTS
F. There are also cold currents in the North Atlantic, like the Labrador Current. The cold currents are important in their effects on climate, navigation, and fishing.One of the world's best fisheries is just off the coast of Iceland because of the Labrador Current. In the case in the North Atlantic, the Labrador Current also brings icebergs to the busy shipping lines of the North Atlantic. (Icebergs, shipping lanes, is there a connection to any major maritime disaster?)
G. The pattern for Oceanic currents is similar to Atmospheric currents. Warm waters from the tropics move toward the poles while cooler waters from the poles move toward the tropics.Warm currents increase humidity and warm east coasts of continents. The quality of cool currents are drying and cool the west coast of continents.
UPWELLING
H. The cold currents along the west coast of continents in subtropical latitudes are regularly strengthen by upwelling caused by the trade winds driving surface waters offshore (the trade winds literally drag the surface waters away from the coast) and colder waters rise up filling the gap and bring with them many small marine organisms that support fish in shallow waters and create great fishing grounds. Examples are the California, Humboldt, Canary and Benguela Currents. (What small fish is caught off the Humboldt, off the coast of Peru and Ecuador, is is wonderful on Pizza? Read on about El Nino in the book and you will know.)
V EL NINO
NORMAL EL NINOS
A. Review the the section I just wrote about the effect of the trade winds off the coast of Peru and Ecuador and the upwelling of the Humboldt current. This is the normal condition for most the year, but in December and January about two and a half months, the trades decrease and even reverse themselves. Since the upwelling of cold water is stopped so does fishing.The local fishermen have adjusted their life-style and repair their nets and boats during this period. The routine is so predictable the it has been given the name El Nino around Christmas time for the Christ Child. It is a normal event.
EL NINO AND THE PROTRACTED EL NINO
B. Sometimes the El Nino does not last just for two and a half months but is protracted for much longer. In the last decade through the poplar press has used the term El Nino for the protracted El Nino and not the normal condition . I do not want to confuse you so I will use the same term but I do want you to know the difference. El Ninos have been documented since the 1726 and in the last fifty years ten El Ninoshave been recorded. These events change not only the temperature of the region but influence the weather all over the world.
EL NINO--SOUTHERN OSCILLATION
C. Sometimes the events half a world away have effects on our daily lives.The El Nino phenomenon is no exception. In the 1930s a British meteorologist made a connection between sea level pressure on both sides of the Pacific.A rise in sea level pressure in the eastern Pacific frequently was coincided with a fall in sea level pressure in the western Pacific.This colossal seesaw is called the Southern Oscillation and was thought for many years to be just another boring science fact.The connection between the Southern Oscillation and El Ninos is so intense it is regarded as one event and is called ENSO (El Nino/Southern Oscillation.) I've talked about the normal conditions when I discussed upwelling. The key is the Southern Oscillation and the change of the pressure gradient which diminishes or even reverse the Trades. Why this happens is still unknown butEl Nino events seem to be increasing and becoming more intense.
EL NINO AND GLOBAL WEATHER
D. Other than seeing flooding in Peru and hearing about the cost of anchovies going up what is the big deal about El Nino? Cold oceanic waters hinder cloud formation which generally located over the western Pacific but during an El Nino the clouds shift to the east and cover the total equatorial waters of the Pacific. (Take a look at Figure 6.7 on p. 142) These are high-altitude clouds reaching as high as 59,000 feet which interfere with high-altitude air flow. (High-altitude air flow will be in another section of these notes.) El Nino has been connected to droughts in Australia, India, Indonesia, the Philippines, Mexico, Central America, and southern Africa. It has also been linked to floods in the western and southern United States, Cuba, northwestern South America, and hurricanes in Tahiti and Hawaii where, normally they are rare. Also hurricanes in the western coast of Mexico became stronger. Snowstorms in the Northeast of the United States were more frequent and more intense in El Nino years. El Nino can be a real boy despite its name.
ATLANTIC CYCLE
E. Since meteorologists began studying El Nino in earnest a similar phenomenon to the Southern Oscillation has been observed in the Atlantic called the Atlantic Cycle which tends to increase rainfall and temperatures in the southeast United States. Atmospheric circulation and Oceanic Circulation are interrelated and the concept of one Earth system is only confirmed by events like El Nino.
VI SUB GLOBAL SURFACE WIND SYSTEMS
MONSOON WINDS
A. So far I've discussed major world systems of heating and cooling which change air pressure and moves the weather. However, there is a smaller scale, or a sub global scale which is just as important. This is the monsoon winds which are seasonal changes in temperature over a very large section of the world. Even more important is precipitation which is a matter of life or death.
B. The most important change in the worldwide framework of circulation is the monsoons in southern and eastern Asia. If your geography needs a little refresher the area most associated with the monsoon is the Indian subcontinent. The word monsoon comes from Arabic, meaning season, but it could also mean life. The monsoon is a reversal of winds from the normal trade wind pattern blowing from northeast called offshore flow, to the southwest. When the winds shift to the southwest they carry vast amounts of water called onshore flow. It is a 180š shift of the directions of the wind caused by the changes in air pressure from high pressure in winter to low pressure in summer. There is also a shift of the Intertropical Convergence to a location over southern Asia. The warm moist air like all trade winds rushes into the low pressure system. Like other low pressure systems the warm moist air will only release its water when it encounters some turbulences or a landform barrier. (What is the topographic barrier influences the precipitation over the Indian subcontinent?) For a visual reminder (Take a look at Figure 6.8 on p. 144.)
THE IMPORTANCE OF THE MONSOON
C. The mechanism of the monsoon is still not fully understood and may be connected to the jet stream. However, the importance of the Monsoon is understood because over half of the population of the world lives in regions which depend on the monsoon for survival. It is this time of year when the rice patties are planted in many parts of Asia. These are "underdeveloped" countries and rely on agriculture. If the monsoon fails or even if it is late there is the possibility of famine.
MONSOON SYSTEMS
D. There are two major systems of monsoons and two minor systems.I've already discussed the monsoon system of the Indian subcontinent. The other major system has even more people and that system waters China, Korea, and Japan.The system is the same but not as intense.There are two minor systems, one in northern Australia, and the other off West Africa.Like many things in geography not all text books agree on all points. Some regions like the southern United States have "monsoonal tendencies." The local weather men talk about monsoon during the summer, but these are more "monsoonal tendencies." (Why does the southern United States and even Colorado only have "monsoonal tendencies" and not true monsoons?)
VII LOCAL WINDS
A. The chapter so far has only covered the major wind belts, which predominance the climate of the planet but there are some important local wind systems.These winds are like the major wind systems but on a much smaller scale. Like their big brothers they are formed from pressure gradients and topographic features. They work with the more important systems. They are: Land Breeze-Sea Breeze, Mountain Breeze-Valley Breeze, Drainage Winds or Katabatic Winds, and Foehn Winds.
SEA AND LAND BREEZES
B. Sea breezes and Land Breezes are very widespread in the tropics but less developed during the summer in midlatitudes. (Take a look at Figure 6.9 on p. 145 for the daily pattern.) Sea breezes come in from the sea during the day and land breezes blow out from the land at night. It is like other systems, it works on convection caused by the difference between land and water heating.
This sea breeze and land breeze is not limited to just coastal cites but cities like Chicago and Milwaukee on the Great Lakes or other bodies of large fresh water.
MOUNTAIN AND VALLEY BREEZES
C. In many mountain areas like Colorado, the daily conduction and Re-radiation from the land causes the air to rise near the mountain slopes, more than the surrounding low lying areas. The warm air rises, creating a low-pressure area and the cooler air flows from the valley floor up the slopes of the mountain. This is called a valley breeze or upslope conditions. Clouds are created around the peaks and afternoon drizzles occur almost daily. Sometimes you can even see the clouds creeping up the mountain from the mid-morning to early afternoon. In some places you can almost count on a drizzle around 4:00 pm. during the summer. (Take a look at Figure 6.10 on p. 145 for the daily pattern.)
D. The pattern is reversed at night when the slopes quickly lose heat and cool the air. Mountain breezes of cool air falls down the slope and stays in the valley. Mountain breezes can happen in summer, but are more common in winter and are called air drainage. I discussed this before in the last set of notes concerning inversions.
DRAINAGE WINDS OR KATABATIC WINDS
E. A more common and commanding type of air drainage are the katabatic winds. Their source is in cold upland areas and fall into lower elevations, remember cold air is denser than warm air. These very cold winds are very widespread in Greenland and Antarctica and come off the ice sheets. When channeled through a valley they can become very destructive.They can happen in other places as well like the mistral which roars down France's Rhone Valley from the Alps to the Mediterranean Sea. There are other similar winds like bora in the Adriatic (Yugoslavia) and the taku in southeastern Alaska.
FOEHN/CHINOOK WINDS
F. Foehn wind has several names depending on what part of the world that does the naming. The most famous is the chinook winds, which move down the eastern slopes of the Rockies. Sometimes on the weather reports you can hear about up slope or down slope winds, chinook winds are down slope winds. Chinook Winds begins when a steep pressure gradient develops on the windward side of a mountain and there is a low-pressure trough on the leeward side. The air is forced over the mountain because of pressure. As the air flows down the leeward side it is compressed and heated and is dry and warm because it has lost moisture on the windward side. (Take a look at Figure 6.11 on p. 146)
G. The Chinook is called the snow-eater. These winds not only increase temperatures, but are drying as well and can suck up moisture. Part of the problem during the Dust Bowl was caused by Chinook winds. The foehn (pronounced "fern") are the same type of winds, but occur in the Swiss Alps. Similar winds are called Santa Anas, very dry foehn-type wind, in California which can fan brush fires usually in late summer and fall. For what it is worth, some research that suicides and crimes of passion increase when these winds are blowing. It has been used a successful defense in many parts of the world.
VIII UPPER AIR WINDS
A. The notes so far have discussed surface wind systems. Even more important are the wind systems above the Earth's surface. According to your text high-altitudes begin above 16,500 feet in the upper troposphere. It is as good as any place to start. The circulation of upper air winds is simple compared to surface level winds. They flow in a geostrophic pattern in the upper troposphere and two patterns can be seen which are the same pattern as surface winds. The first is the upper air westerlies, and are located about 15š to 20š in both the Northern and Southern Hemisphere between 15š and 20š North and South are the upper air easterlies which are extensions of the trade wind system.
THE DISCOVERY OF THE JET STREAM
B. It was during World War II, when American B-29s flying a high altitudes on missions to bomb Japan discovered that air speed and ground speed were different. They were almost standing still because of head winds (they were headed east) but coming back from their missions their speed almost doubled because of tail winds (they were headed west). Later investigations sometimes using weather balloons; which have been mistaken for UFO's, have confirmed the observation of American bombers. What was discovered was the polar jet stream in the upper air westerlies.
THE POLAR JET STREAM
C. The Polar Jet Stream is perhaps the best known of the Jet Streams in North America because it is typically featured on weather broadcasts.(It would not be a bad idea to carefully watch the nightly weather broadcasts, perhaps some of the things I've talk about in class might make better sense.) This jet stream is found between 25,000 to 35,000 feet, 7600 to 10,700 meters in altitude and can be 25 to 100 miles wide, and one to two miles, one to three kilometers deep.(Different text books vary just a little bit on the specifics, but they are all close.) They can be thought as faster moving current in the upper westerlies the predominate wind flow in midlatitude locations. Perhaps the best way to visualize the jet stream is as a tunnel of very faster air in the upper westerlies.
SUBTROPICAL JET STREAM
D. The jet streams are not an individual wind but zones of intense winds. The speed of the jet stream is usually around Sixty knots, but some speeds of over 300 knots, 350 miles per hour, have been recorded. The polar jet stream is not the only jet stream over the Northern Hemisphere. There is the subtropical jet stream, although it is about the same altitudes as the polar jet stream it is generally weaker of the two jet streams. (Take a look at Figure 6.15 for the location of each jet stream) The subpolar is a little closer to the poles than the rest of the westerlies, while the subtropical jet stream is just a little closer to the equator.
ROSSBY WAVES
E. The polar jet stream changes its latitudinal position north and south during the seasons. The reason for this meandering is due to Rossby waves they normally divide zones of cold air (polar air) from warm (tropical air.) However, there are oscillations (long waves) in the Rossby waves which cause the cold polar air to drift down to lower latitudes. (Take a look at Figures 6.16 a, b, and c on p. 149) Like many things dealing with the weather it is not completely understood why these oscillations occur.
THE IMPORTANCE OF THE JET STREAM.
F. The location and speed of the jet stream is important to aircraft, because it can cut time and save fuel, but is also important in weather forecasts because some storms track just below the jet stream. Others things in the air are also influenced by the jet streams the ash from Mount St. Helens and the Nuclear fallout from Chernobyl were carried across the oceans.
GUIDED PRACTICE
Questions during the lecture.
INDEPENDENT PRACTICE
Readings at home

Culmination

List the processes which moves the winds? How are the Modifications of the General Circulation important to places like India?

What is the model of the Global Wind systems? Localized Wind Systems can be important --How do they work?

How is it connected to pressure belts? What are the Upper Air Winds and the jet stream?

The Atmosphere acts as a thermostats for the entire planet--Explain?

How many Wind belts are there?

Ocean Currents move the waters of the world know about the warm ones and cold ones.

El Nino and the Southern Oscillation--Why?

Front Page

ANTICIPATORY SET
What starts the process which moves the winds?	What is El Nino and the Southern Oscillation?
Where are the Global Surface Wind Systems and how do they work?	What are Sub-Global Wind Systems?
How does the General Circulation of the Atmosphere act as a thermostats for the entire planet?	How are the Modifications of the General Circulation important to places like India?
How many Wind belts are there?	What are the Localized Wind Systems?
Where are the Ocean Currents and what do they do?	What are the Upper Air Winds?
BEHAVIORAL OBJECTIVES	These are the fast ones.
To trace the General Circulation of the Atmosphere in theory.	To point out the connection between pressure systems and wind systems.
To evaluate the Trade Winds.	To identity polar easterlies, westerlies, and trade winds. (Each hemisphere has matching systems.)
To locate the Intertropical Convergence Zone also called the Doldrums.	To investigate El Nino and the Southern Oscillation.
To classify and locate Subtropical Highs.	To sketch El Nino and Global Weather and the Atlantic Cycle.
To describe the Westerlies.	To evaluate the importance of Monsoons
To compare and contrast the polar front jet stream and subtropical jet stream.	To outline Localized Wind Systems.
To identity Polar Winds and Polar Front.	To identity Land and Sea Breezes, Valley and Mountain Breezes, and Drainage Winds or Katabatic Winds.
To investigate Seasonal Variations in Location	To identify the bora, mistral, and the Taku.
To outline Ocean Currents and their general pattern.	To review Foehn winds like
To list the oceans of the World.	Chinook and Santa Ana Winds .
To identify gyres.	To describe Upper Air Winds like the Jet Streams.
To discuss the influences of Cold and Currents on, fishing climate, navigation and the Land masses	To identify the polar jet stream, subtropical jet stream and Rossby waves.

1. Polar highs	2. Polar Easterlies	3. Subpolar lows	4. Westerlies
5. Subtropical highs	6. Trade Winds	7. Intertropical	Convergence Zones.

Culmination
List the processes which moves the winds?	How are the Modifications of the General Circulation important to places like India?
What is the model of the Global Wind systems?	Localized Wind Systems can be important --How do they work?
How is it connected to pressure belts?	What are the Upper Air Winds and the jet stream?
The Atmosphere acts as a thermostats for the entire planet--Explain?
How many Wind belts are there?
Ocean Currents move the waters of the world know about the warm ones and cold ones.
El Nino and the Southern Oscillation--Why?