GEOGRAPHY 101 Front PageTHE ATMOSPHERE, ATMOSPHERIC HEATING,
AND TEMPERATUREMATERIALS 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 ATLASGENERAL OUTLINE:
IV. The Atmosphere, Atmospheric Heating, and TemperatureA. To classify the Characteristics and Composition of the Atmosphere.
B. To describe the vertical structure of the Atmosphere
C. To compare and contrast Weather and Climate.
D. To list the Elements of Weather and Climate.
E. To identify the Controls of Weather and Climate--(Latitude, Land and
Water Distribution, Ocean Currents, Altitude, topographic barriers or
landform barriers, human activities.)
F. To sketch the impact of Solar Energy and Atmospheric Dynamics. (The key
to this section and other sections is the Electromagnetic
Energy--Electromagnetic Spectrum)
G. To recall the Role of Water in the Atmosphere and the Effects of the
Atmosphere on Solar Radiation.
H. To detail the Heating of the Atmosphere particularly the Methods of Heat
Energy Transfer.
I. To outline the Heat Energy Budget and variations in the Heat Energy
Budget.
G. To compare and contrast the different scales of temperature.
H. To outline Short Term Variations in Temperature, and the difference
between land and water heating.
J. To discern Vertical Temperature Patterns--Know Normal Lapse Rates.
K. To define Temperature Inversions.
L. To compare and contrast Global Temperature Patterns at the Earth's
Surface.
M. To compare and contrast the Annual March of Temperature.THE MATERIAL IN THIS OUTLINE COVERS PAGES 90-114 BUT THERE IS MATERIAL NOT IN YOUR BOOK--KNOW IT--KNOW IT--KNOW IT
ANTICIPATORY SET
How does the Atmosphere affect life on this planet and could it be said that Air could be called an "Ocean of Air" ? What is the Vertical Structure of the Atmosphere? What are the controls of Weather and Climate--Is there an on off switch? What are the major elements of Weather and Climate? What is Solar Energy and what are Atmospheric Dynamics ?
It is important to understand the Electromagnetic Spectrum.What is the Heat Energy Budget for the planet and how does it vary? What is the role of Water ? What are the Short Term Variations in Temperature ? How can Solar Energy be broken down? What is the Vertical Structure of Temperature? What are the Mechanisms for Heat Transfer? How is Temperature Distributed on the Earth's Surface? What are the Global Temperature Patterns and what are the Seasonal Patterns.?
BEHAVIORAL OBJECTIVES
To define the Atmosphere as and Ocean of Air. To compare and contrast Weather and Climate. To recall Advection heat transfer. To describe the Composition of the Atmosphere as a mixture of gases and to point out it is everywhere To recount and list the Elements of Weather and Climate. To describe the Heat Budget To identify the Gases in the Atmosphere and describe the process of Oxidation. To sketch and list the Controls of Weather and Climate To compare and contrast Temperature and Heat. To identify the process of photosynthesis. To depict the Controls of Latitude, Distribution Land and Water, General To recognize the importance to Daily March of Temperature and Atmospheric Obstruction To recall the significance of Carbon Dioxide CO2 and Ozone O3 and point out the importance of the the Ozone layer. Circulation of the Atmosphere, the General Circulation of the Oceans, Elevation, Topography Barriers, Storms To recount the Land and Water Contrasts in heating, cooling, and the implications What are the Particles in the Atmosphere?
To portray the Vertical Structure of the AtmosphereTo identify short and long wave radiation. To recognize reflection and Horizontal Air Movement. To stress the importance of the troposphere--This is where To investigate the Electromagnetic Spectrum To discern the Lapse Rate. the weather happens
To recognize role of the thermosphere once called the ionosphere--Just tune in.To identify a calorie and solar constant. To relate the three forms of water. To describe Temperature Inversions. To identify Latent Heat and use the example of evaporation and condensation. To recount Isotherms and the temperature gradient To compare and contrast Conduction and Convection. To describe the Annual March of temperature INSTRUCTIONAL INPUT
Content Methods:LectureandClassroomdiscussionOVERVIEW:
BREATH EASIER BECAUSE OF THE ATMOSPHERE
WHY AIR?Many years ago Bill Cosby, who at that time was a stand-up comedian, had a routine called "Why Air", it was very funny, but the point of the routine was that air was needed to inflate Basketballs. This is true, but air is more than just inflating Basketballs. Without air there would be no life on this planet. Animals, including man, need oxygen to live, and plants need carbon dioxide. Air is also very important to the water cycle, and helps protect the Earth from ultraviolet rays of the Sun; which would be lethal to life as we know it. The Atmosphere gives color to the skies. Plants need air to pollinate, birds need it to fly, the Atmosphere also conducts sound and the atmosphere acts as a thermostat balancing temperature and air pressure for the planet.
THE ATMOSPHERE IS AN OCEAN OF AIR
Atmosphere is a fancy name for air. The atmosphere should be considered as an Ocean of Air, but a very shallow one. Like the ocean, the atmosphere moves and most of it is below 18,000 feet in elevation or about the elevation of Mount McKinley in Alaska, but part of the atmosphere extends to 6,000 miles. As people in Colorado know it becomes thinner as altitude increases and about 97 percent of it is contained below eighteen miles. At sea level the air pressure is 14.7 lbs per square inches and decrease with altitude. (Chapter five will deal with air pressure.)
I THE COMPOSITION OF THE ATMOSPHERE
THE EARTH'S ATMOSPHERE IS MOSTLY NITROGEN AND OXYGEN
A. Most of the atmosphere of the Earth is Nitrogen (about 78 percent) and Oxygen (about 21 percent.) Argon, an inert gas and some trace gases make up the rest. (Take a look at Table 4.1 on p. 92) Nitrogen is critical to nutriment for plant growth and comes from decomposing and burning of organic matter and the breakdown of certain rocks. Oxygen is more than just the air we breath, animals oxidize (burn) the food they eat. Oxidation is a chemical process of oxygen and other materials and is part of the inorganic process as well. Rapid oxidation occurs when things are burned, in addition, great amounts of heat is released. The decomposition of some rocks and organic material are examples of slow oxidation. (What is the most common example of low level oxidation when Fe comes in contact with H 2 O.)
CARBON DIOXIDE AND GLOBAL WARMING
B. Another important gas in the atmosphere is Carbon Dioxide, because it has a major influence on climate. It absorbs infrared radiation from the sun and keeps the lower atmosphere warm. Since the "Industrial Revolution"; which started in England about two hundred years ago, Carbon Dioxide in the Atmosphere has been increasing. At first it was the burning of coal, which fueled the first factories and later the burning of oil, natural gas, and gasoline. These fossil fuels and the Carbon Dioxide they release have possibly been linked to "Global Warming," this is also called the "Greenhouse Effect". Carbon Dioxide makes the atmosphere a little less transparent and according to the theory, the Earth becomes warmer. This will cause massive climatic changes. Not all scientists agree with this theory.
PHOTOSYNTHESIS--AN OPEN SYSTEM
C. If you remember systems, photosynthesis is a good example of the carbon cycle or a system. Green plants convert sunlight (energy), water, and nutriments from the soil, and carbon dioxide to make carbohydrates (sugars and starches) where energy is stored. Oxygen is a byproduct of this process (Take a look at Figure 4.1 on p. 93) Animals use oxygen to oxidize the carbohydrates, freeing the stored energy and a byproduct of this process is carbon dioxide.
OZONE AND OZONE LAYER
D. Another minor but important gas in the atmosphere is ozone. Ozone (O3 ) is different than regular oxygen (O2 ) because it has three atoms of oxygen. Ozone is formed in the upper atmosphere between nine and thirty miles over the surface of the Earth. This ozone layer of the atmosphere filters out ultraviolet radiation. Excessive ultraviolet radiation can cause skin cancer, kill some forms of microscopic life forms, and decrease crop yields. The fragile ozone layer is being attacked by a chemical called chlorofluorocarbons (CFCs.) These are man-made chemicals and are compounds of chlorine, fluorine, and carbon . These are chemicals have been used in air conditioners, aerosols, and refrigerators. (Take a look on the description of Negative Feedback Loop on p.11-12.) These chemicals have created an ozone hole over Antarctica but international treaties limiting their use seem to have slowed this process.
WATER VAPOR IN THE ATMOSPHERE
E. Water is only a small percentage of the atmosphere and varies depending on location and time of the year. It increases near tropical oceans and decrease over the poles and deserts. As a whole, water vapor is almost constant over the atmosphere. Water vapor plays a major role in weather and climate. Besides water vapor, (the gaseous form) liquid water exists in the clouds and solid water (ice) is suspended in the form of ice crystals, snow, or hail.
SOLIDS IN THE ATMOSPHERE
F. Hanging in the atmosphere are solids. One solid is dust particles from natural sources like volcanic ash, wind-blown soil, pollen grains, and salt from the ocean's waves these have been around since the beginning of the planet. Man can also make the problem worse from his own action. Dust does not usually remain in the atmosphere very long. Smaller particles are a different matter and can remain in the atmosphere for months or years. Suspended matter in the atmosphere are called particulates.
PARTICULATES ADVANTAGES AND DISADVANTAGES
G. There are more smaller particles than larger particles. As could be expected the concentrations of particulates are over cities and volcanoes, but they do not stay there. They are moved in the atmosphere by the wind, hundreds or even thousands of miles from their point of origin. A problem with particulates is they can either absorb or reflect sunlight, limiting the amount of solar radiation. Particulates are also hygroscopic, they absorb water and water vapor condenses around them which is the essential step in the development of raindrops.
II VERTICAL STRUCTURE OF THE ATMOSPHERE
A. As we already know, in Colorado the air becomes thinner as altitude increases. Your book mentions Inca ruins in the Andes, mountain climbers in the Himalayas, and skiers in the Rockies. It did forget important things like how a curve ball does not curve very well at Coors Field but more home runs can be hit there. The author's point is it takes time for people to adjust to high-altitude.
TEMPERATURE--KNOW THE PATTERN OF THE ATMOSPHERE
B. The vertical pattern of temperature is complicated. It is more than the temperature decreasing when someone climbs up Pikes' Peak or some other mountain. The atmosphere is a succession of layers. Which either get warmer or cooler in a zig-zag pattern. (Take a look at Figure 4.2 on p. 94 to understand the decreasing and increasing pattern.) It is nice to know all the different layers, their altitudes and characteristics if you are sending a rocket aloft, but with two exceptions outside of the Troposphere, All I want you to know is the pattern.
TROPOSPHERE
C. The Greek name can describe the Troposphere best a mixing or turning zone. It is the layer of atmosphere closest to the surface of the Earth. The focus of the course is on one layer of the atmosphere called the TROPOSPHERE. The air density of the troposphere changes from season to season. It is shallower at the poles and deeper at the equator and ninety percent of the total atmosphere is in this layer. The troposphere is where most living things live (the biosphere) and where interesting things like weather happen. Unlike the other layers it has two important characteristics. First, most of the water vapor and dust particles are found in this layer. Second, in this layer temperatures usually decrease with increased altitude. All a person has to do is watch the local weather to know that usually Colorado Springs has a lower temperature than Pueblo. I'll go into details a little later in this chapter.
STRATOSPHERE & THE OZONE LAYER
D. The Stratosphere is the second belt of atmosphere and starts about eleven miles above the Earth and ends about thirty miles higher (Some sources vary about the thickness of this layer.) Temperature range is about -70š F and it is in this layer that ozone (O 3) is concentrated.
THERMOSPHERE=IONOSPHERE
E. According to your text this zone of atmosphere was once called the ionosphere, but is now called the thermosphere. Other current sources still use the old name. I'll use both so pay attention. The thermosphere/ionosphere lies between 40 and 250 miles up. The significance of the thermosphere/ionosphere is the molecules and atoms in this zone are electrically charged and are called ions. These molecules reflect radio waves and make some long-distance communication possible in the AM band. They work better at night that is why a station like KOA from Denver can be heard in Mexico City. (Why does it work better at night?) This layer of atmosphere is where the Northern lights, an electrical phenomena, can be seen if you are far enough north, they are also called the Aurora Borealis.
III WEATHER AND CLIMATE KNOW THE DIFFERENCE
WEATHER--SHORT TERM
A. The atmosphere is affected by several factors and reacts in different ways depending on those factors. The state of the atmosphere at any given time for a specific area is called the weather. The area could be as large as a major city or a very small location. Weather is short term and passes in a few weeks or months. It is always changing. Remember it is troposphere, the lowest layer of the atmosphere, where the action is, as far as weather is concerned. The scientific study of the atmosphere is called meteorology.
CLIMATE--LONG TERM
B. Climate is weather for a long period of time. It is not just the general tendencies of a given place, but the radical changes as well. Weather data, which has only been collected over the last hundred years in some places, is the best measure of climate. Climate takes into account the variations and extremes of weather, the seasonal averages, and also factors in things like storms. Climate does change over time, sometimes due to natural causes, other times because of man-made causes. The scientific study of different climates is called climatology. This study includes past and current climates and tries to predict future climates.
C. It almost goes without saying that weather and climate have a direct influence on living patterns. Agriculture you can't grow certain crops in certain places. It might be too hot or too cold, or the precipitation is not the right amount, or the soil is wrong for certain crops. This list is almost endless. Sometimes people move to better climates. In recent years many people in the United States have moved to the Sun Belt, the southern tier of states. A major reason was to escape the cold northern winters. Depending on the climate, the physical landscape can change.
THE ELEMENTS OF WEATHER AND CLIMATE
D. Weather and climate is an intricate machine. It could be called the great "Weather Machine" (In this case I'm using Weather in its broadest sense and climate would be part of this definition), and like any machine it can be understood by looking at its systems. Both weather and climate have five major elements. Know the Elements of Weather and Climate.
1. Insolation, sunlight, solar energy
2. Temperature which can be expressed in Fahrenheit or Celsius
3. Air Pressure (This can be expressed either by Barometric pressure or in
millibars depending on how scientific want to be.)
4. Wind which can be expressed by miles, kilometers, or knots
5. Precipitation and Moisture content (humidity)The intensity and duration of insolation is the determining factor in weather for a given place. The next time you watch the weather report you will hear about temperature, highs and lows, the Barometric pressure, the wind speed, and the humidity (water vapor). You might listen to whether it might rain, snow, or something in between. There might even be some type of storm coming as well. Depending on how they are interacting might determine what you are going to wear for the day or whether you should you take a trip to the mountains, or buy several days of food.
IV THE CONTROLS OF WEATHER AND CLIMATE
A. Like an automobile or any other machine weather and climate have controls. These are variables in the weather and climate pattern. These controls interact between each other and cause the differences in climate and weather. There are six controls on weather and climate. I going into details on each one so know the controls of weather and climate.
1. Latitude
2. Distribution of land and water
3. General circulation of the oceans
4. Elevation or Altitude
5. Topographic barriers or Landform barriers
6. Human activityLATITUDE
B. The most critical control for weather and climate is latitude. Since the Earth and the Sun change positions during the seasons, the amount of sunlight can vary and the radiant energy can be different at different times. Remember the inclination and parallelism of the Earth and how the tropics receive more intensity and for a longer duration of insolation than places north or south from them. The control between latitude and the elements of weather and climate is temperature. Temperate usually declines from lower latitudes to higher latitudes.(Take a look again at Figure 3.14 on p. 87. You also might examine Table 4.2 on p. 96.) Like many things in geography there is an exception. Near the equator, where we might expect the highest temperatures this is not the case. The temperature near the equator is modified because of the extensive cloud cover. However, areas just a little north and south of the equator because of clear skies have higher temperatures.
DISTRIBUTION OF LAND AND WATER
C. The world ocean is a great storehouse for water on planet Earth, but they also hold immense reservoirs of heat. All things heat up or cool down at different rates as a generalization land heats and cools faster than water. The land is made up of solid materials and the heat remains near the surface. In short, it is the nature of the surface itself which determines the rate of cooling and heating. Soils, forests, grasses, snow, and cities, all have different rates of cooling and heating. (What is the warner air called over a city?)
WATER AND HEAT
D. Water dissipates heat in several ways: First, by evaporation, a cooling process. Second, water is moved or mixed by the wind and ocean currents. Third, the specific heat of water is four times that of land which means water can absorb heat. Just think of water as great heat sponge. Fourth, certain light waves can pass through certain materials like clear glass. This is called transmission. Clear materials are better transmitters than solids. Water is a very good transmitter. If you want a less technical reason, water is transparent.
E. There is a very big difference between maritime climates and those of continents. The oceans of the world do not show as much temperature change as the land. Areas along seacoasts generally have less changes in temperatures than places along the same line of latitude further inland. Since the spatial arrangement of oceans and continents are irregular, they are a major control of the elements of moisture and temperature.Your book uses the specific example of Seattle and Minneapolis which are on the same latitude but have very different climates.
GENERAL CIRCULATION OF THE OCEANS
CORIOLIS EFFECT--AGAINF. Oceanic currents aid in the heat transfer of warm water to the poles, and cold water to the tropics. It could be said that the oceans act as a thermostat for the entire planet.They can loosely be called rivers in the ocean. In the Southern Hemisphere the currents run counterclockwise, while the currents in the Northern Hemisphere the run clockwise. This effect is called the Coriolis Effect. The Coriolis Effect is mainly caused by the Earth's rotation, but the wind does play a part. (Take a look at Figure 4.3 on p. 98.)
OCEAN CURRENTS
G. Some currents warm the lands they touch, like the Gulf Stream and its extension, the North Atlantic Drift, warms Western Europe. Labrador which is the same Latitude as Great Britain a has very different climate. Labrador is on the North-East coast of Canada and is very cold. Temperatures can get below freezing, even in summer and the ports are ice bound for six months. Great Britain and the rest of Western Europe is very mild in comparison and most of the ports remain ice free, at least those which face the Atlantic.
ELEVATION
H. Living in Colorado all one has to do is to drive up Pikes' Peak to see the changes of climatic zones. The weather elements temperature, pressure, and moisture decrease with elevation. If you do take the drive you will notice that they have the temperature at the base of the mountain and a much cooler temperature at the top. This is for tourists who think they can wear shorts at 14,000 feet. What also should be mentioned is carburetors sometimes malfunction if they are are adjusted for low altitudes.
TOPOGRAPHIC BARRIERS OR LANDFORM BARRIERS
I. Mountain ranges or even large hills can sometimes be barriers to the wind. The wind literately hits a stone wall and must rise over it. In doing so the moisture laden air gets cold and either rainfall or snowfall happens. In many cases the windward side of mountains get more precipitation then the sheltered or leeward (sheltered) side. In North America most of the mountain ranges, Rockies, Cascades, or the Sierras run north-to-south and obstruct the moisture laden air from the Pacific. On the eastern leeward sides of these mountains there are deserts. This is called the rain shadow effect. (I've talked about this before in passing and will mention when I discuss precipitation.) (Take a look a Figure 7.14 on p. 175.)
THE NORTH AMERICAN EXAMPLE
J. The location of the mountain ranges allows Arctic air to slide down moving southwards in winter and dropping temperatures in the heart of the continent. This usually affects the Midwest and the Northeast but sometimes can cause freezes as far south as Florida. During the spring and summer the warm moist air comes up from the Gulf of Mexico traveling northward and mixes with the Arctic air. The result can be cold fronts with thunderstorms and killer tornadoes in the Central United States.
K. People are a control on weather and climate. They build cities, burn fossil fuels, drain swamps, devastate forests, and build large dams. These things can change the climatic patterns on the local scale and perhaps the climate of the planet. However, they can make parks in cities, turn to other fuel sources or use them more efficiently, replant forests, and tear down dams. I think I remember something called Space Ship Earth.
V SOLAR ENERGY AND ATMOSPHERIC DYNAMICS
ENERGY FROM THE SUN
A. Essentially, all the energy comes from the Sun, in the shape of electromagnetic energy which travels at light speed to the Earth. This energy reaches Earth in the form of electromagnetic waves, unlike other waves, they pass through space unchanged and only takes 8 minutes for these waves to reach Earth. (There are other sources of heat energy like geothermal but they are insignificant.) As I've mentioned, the Sun makes life on this planet possible and on the cosmic scale, the Sun is only average. What makes the Sun different is it's nearness by cosmic terms, to the Earth. (Take a look at Figure 4.5 on p. 99--Also take a quick look about the total Electromagnetic spectrum in Chapter 2.)
REMEMBER THE ELECTROMAGNETIC SPECTRUM
B. Isolation from the Sun is mostly in the visible part of the spectrum, according to your text about 41 percent, (Other texts place it at high as 47 percent.) but does contain infrared and ultraviolet waves. Solar radiation is shortwave radiation, while cool bodies like Earth radiate long waves. All radiation from Earth is long wave radiation. Long wave radiation will become very important (Take a look at Figure 4.5 on p. 99. This time look at the two arrows above the main graphic and read the cutline.)
C. Electromagnetic waves of various lengths or frequencies make up the electromagnetic spectrum and can be called radiation or energy. Other parts of the Electromagnetic spectrum can not be seen by the human eye, but can be detected by special instruments. The most familiar forms are radio waves and light waves which are used for communications and in the field of remote sensing. Less familiar are infrared, ultraviolet light, X-rays, and gamma rays.
ELECTROMAGNETIC SPECTRUM IN PHYSICAL GEOGRAPHY
D. There are three bands of the electromagnetic spectrum which concern Physical Geography. The first is Ultraviolet waves, which is too short to be seen by the human eye. Most ultraviolet waves are screened by the atmosphere in the Ozone layer, but should more of them reach Earth most life on this planet might die. The second is Visible Light, this is the light we can see but of the entire electromagnetic spectrum only about three percent is visible to the human eye. The third type of wave or radiation is infrared waves. These waves can pass through some objects like glass, while other parts of the spectrum are blocked. This is how a green house works, the infrared waves are also called heat waves. I'll talk more about this later.
INTERCEPTED ENERGY--THE SOLAR CONSTANT
E. The insolation from the sun at the top of the atmosphere is a relative constant (an average) over the year but there some minor swings. This steady amount of insolation is called the solar constant. This intercepted energy equals 1.97 calories per square centimeter per minute. A calorie is the amount of heat required to raise the temperature of 1 gram of water 1š C. (There are other units of measurement like langleys, watts, and joules just in case you are interested.) The solar constant has been calculated by several satellites and is a concern for long term climate patterns.
F. The intercepted energy from the sun is just the beginning of a set of complex reactions between the Earth and the Sun. The atmosphere reflects some of the energy back to space, some of it is refracted by the atmosphere, some of it is absorbed by clouds, and some it is changed in form. This energy cascade is the topic of not only this chapter but some others as well. However, other things must be discussed before we can get to them.
VI THE ROLE OF WATER
TEMPERATURE RANGE OF WATER
A. Water is amazing in many ways and yet it is so common. Water is the only substance that can occur in all three stages of matter; as a solid, liquid, and a gas at the normal temperature range of the planet. In the atmosphere, it can exist as water vapor, a clear odorless gas, but it can also exist as a liquid in the atmosphere or as a solid as well. Most of the water on the Earth is in the form of liquid and is contained in the world ocean and other bodies of water, but it is also in plants, animals, and underground. Water is solid in snow and ice in the atmosphere as it is locked in the great sheets of ice near the poles or on high mountains. Yes, I know every school child knows most of this material already, some things are hard in this course some things are easy, just wait there is much harder material to come.
LATENT HEAT-- KNOW THE TECHNICAL PROCESS
B. Water is stored in all three forms of matter, but can change form very quickly. (Take a look at Figure 4.6 on p. 100. Like many things in this course the graphic can be more important than the words.) These changes of water into different forms also involve exchanges of energy. The quantity of heat absorbed or released by a substance undergoing a change of state is called latent heat. Water vapor can be changed to liquid water by condensation. In gaseous state of water the molecules move faster than a liquid state so in the process of condensation the molecules slow down and some of the energy is released. (590 calories per gram) The molecules of solid water moves even slower than the liquid form so when liquid water is in the process of freezing to ice latent heat is released (80 calories per gram.)(YOU NEED TO KNOW THE PROCESS OF LATENT HEAT NOT THE NUMBERS)
SUBLIMATION
C. The process is the opposite in melting which needs increased energy (80 calories per gram.) Evaporation demands even more energy (590 calories per gram.) There is another process called sublimation (know the two sides of sublimation) Sublimation is the process when water goes from the gaseous stage directly to a solid state and bypasses the the liquid state, however it can go from solid state (ice) to the gaseous stage just as easily. The key is latent heat or whether it is being released or stored. (Depending on which direction the plus or minus energy exchange is 670 calories per gram.) It is the application of this process which makes freeze-dried foods.
VII EFFECTS OF THE ATMOSPHERE ON
SOLAR RADIATIONTHE HEAT PROCESS IN THE ATMOSPHERE
A. The process of heat transfer must be understood before we look at what happens to that process in the Atmosphere. There are several factors involved as insolation reaches the Earth's surface. The first is location on the surface of the Earth, the second time of day and time of year, but the condition of the atmosphere is also a factor. When heat or energy reaches Earth it can be reflected, scattered, or absorbed by the atmosphere.
B. Reflection is when an object can deflect or bounce off incoming radiation and is not a factor in heating the atmosphere and the best analogy is a mirror. Twenty-six percent of insolation is reflected back into space by clouds and the land surfaces. Another eight percent is scattered by particles in the atmosphere and returns to space. (Take a look at Figure 4.7 on pp 102-103 and read the cutline several times.)
SCATTERING OR DIFFUSE RADIATION
C. Twenty percent of insolation reaches the Earth's surface but is changed by diffuse radiation or scattered light. This light is multidirectional and is shadowless on the surface. To understand scattering we again have to look at the visible light spectrum (Figure 4-5 on p 99.) Sometimes particulates in the atmosphere deflect incoming light waves, especially violets and blues more than reds and oranges. This is why the sky is blue and not red except for sunrises and sunsets. This process is called Scattering, it changes the direction of the light, but not the wavelength. A rough analogy might be the break in a game of pool, but there would be several cue balls of different sizes and the size of the balls would vary. The wavelength of the light varies as do the particulates in the atmosphere and thus the scattering.
D. About 27 percent reaches the Earth as direct insolation and 19 percent is absorbed or filtered, by the ozone layer in the stratosphere, dust, and by water vapor. (Take a look at Figure 4.7 on pp 102-103 and read the cutline several times.) The average of 47 percent of insolation reaches the surface.
VIII HEATING THE ATMOSPHERE
A. About 19 percent of insolation, (energy) is held in the atmosphere and stored by clouds and the ozone layer and does not heat the troposphere. The 47 percent of solar radiation which reaches the surface is moved from land and water back to the atmosphere in several physical processes:
1. Radiation. 4. Advection 2. Conduction. 5. The Latent heat of
Condensation.3. Convection I'm going into details on each one, so know each of the examples and how they work.
WHY DOES THE EARTH WARM UP--IT IS NOT WHAT YOU MIGHT THINK
B. Radiation is the transfer of electromagnetic energy (heat) from the sun to the Earth. All things emit a certain amount of heat this is Radiation. It could be described as an energy stream from one thing to another, on Earth its has to go through the air. Like many things, temperature is one factor. The warmer a body is the more energy (heat) it will release and the shorter the wavelengths of the emission. The Sun is much warmer than the Earth and radiates energy at shorter wavelengths. (Take a look at Figure 4.5 on p. 99. This time look at the two arrows above the main graphic and read the cutline.) Most the the Earth's radiation is the longer wavelengths.
SHORT AND LONG WAVE RADIATION--KNOW THE PROCESS
C. What happens when heating the planet is the short wave radiation from the sun penetrates the atmosphere and heats the surface, since the surface of the planet is cooler it surrenders energy in the form of long wave radiation. This long wave radiation (terrestrial energy) is reflected back from the surface back to the lower atmosphere where the reradiated terrestrial energy is trapped and is again reflected back to the ground. In short the heat you feel on a summer day is long wave, or terrestrial energy, and not direct sunlight, which makes it warm. Perhaps a useful analogy in describing the heating of the atmosphere is think of like an old-fashioned steam radiator with the Earth being the radiator. Of course, there is just a little more to it that what I've described. By the way if you are thinking of the "greenhouse effect" just keep thinking about it.
CONDUCTION
D. Conduction works on the molecular level. Heat is transferred from one point, molecule by molecule in a chainlike matter, to another object when they are in contact. The hot molecule is excited and bumps into the cooler molecule and in the process, makes the cooler molecular hot and the process continues until both reach the same temperature. There are two examples in the book, my example is similar. Try picking up a frying pan after it has been on the burner, for a while, if it does not have some type of insulating handle wood in the old days or plastic today you will get burned. Metals are excellent conductors, that is why they are used to conduct electricity. It is the same principle but the amount of power is regulated and the wires, usually copper, are insulated.
E. Conduction is only a minor element in atmospheric heating because air is not a very good conductor of heat. Air is a good insulator, this is the principle of storm windows, a thermos bottle, and sleeping bags and ski parkas.
CONVECTION
CONVECTION IS THE THE MORE IMPORTANT OF THE THE TWO
BECAUSE OF THE CONVECTION CURRENTS OF THE ATMOSPHERE AND THE OCEANF. Another form of heat transfer is convection. Heat is moved from one place to another by the movement of heated molecules from one place to another. Like many things in science the technical definitions sometimes can be confusing. Convection is a process of circulation in an air or liquid body. Heated material rises while cooler material sinks. The process is the same whether it is the interior of the Earth, in a pan of water, some of the currents in the atmosphere or ocean. Remember that certain materials radiate heat differently, sometimes the one surface becomes warmer than the surrounding area. It is convection which makes things interesting as far as weather goes, because of the mixing of different air temperatures by convection. It is this constant motion of air and water vapor directed by the heat of the sun which moves the weather of this planet in an unbroken chain. On example of convection currents in the atmosphere are thermals which are warm updrafts of air. (What animals use them?)
ADVECTION
G. Most of the time the movement of convection is perpendicular but sometimes there is some horizontal movement. This lateral movement is called advection. The two principle advection mechanisms in the Earth-atmosphere systems are the winds and the ocean currents. They convey heat (energy) between the tropics and the poles keeping an equilibrium in the systems. Both the winds and the oceans can be thought of as thermostats for the entire planet.
REMINDER
The difference between convection and conduction: is molecules move in space (air or water) from the original heat in convection while in conduction they stay put.
LATENT HEAT OF CONDENSATION
H. As the process of evaporation occurs, a substantial quantity of heat (energy) which is stored in water vapor as latent heat is released. (Take a look at Figure 4.6 on p. 100--Again) The water vapor is moved by advection or convection to other places, where the process of condensation develops and the stored energy is discharged. This is a major process in the exchange of energy. The heat (energy) needed for evaporation cools the atmosphere. The flip-side of evaporation is the latent heat of condensation, it warms the atmosphere. (This will be discussed in further detail in another chapter.) The latent heat of condensation is the generator of many storms on the planet especially hurricanes. (What is the name of the huge hurricane which hit the East coast of the United States in the late summer of 1999?)
IX THE HEAT ENERGY BUDGET
TRANSMISSION AND THE GREENHOUSE EFFECT
A. One of the major themes of this text is the systems approach. The Heat Energy Budget of the planet is an open system and is in dynamic equilibrium. As you might recall, I look at several texts to write these notes when all three have the same analogy it might not be a bad idea to use the same analogy of a parked car and the atmosphere.
B. Sometimes certain light waves can pass through certain materials like clear glass. This is called transmission. Clear materials are better transmitters than solids. Certain wavelengths, like short wave radiation can pass through glass very easily, while long waves do not. An example would be a parked car in the sunlight with the windows up. The inside of the car can become very hot. This is called the greenhouse effect and the same process can happen in the Atmosphere, but with carbon dioxide and water vapor trapping the heat.
VARIATIONS IN THE HEAT ENERGY BUDGET
C. Despite the daily and seasonal variations in temperature in most parts of the world and the extreme temperatures in different parts of the planet, the temperature for the entire planet remains about the same. It is in optimal balance and called Heat Balance or Heat Budget. There are many places on the Earth that are too cold, too hot, too dry, or too wet. The imbalances are caused by the differences in the heat received on different places on the Earth. The difference in heating is due to latitudinal, or spatial and seasonal variations. (Take a look at Figure 4.9 on p. 105)
TEMPERATURE AND HEAT
D. The words temperature and heat have very close meaning but they are different. Heat is a form of energy based on the speed of vibration of the atoms. The faster the vibrations, the more heat generated. Temperature is the average expressed by degree of the hotness or coldness of a substance. There is a difference between the two. The oceans have moderate temperatures but high heat (energy) reserves, while match has high temperatures, but hardly any heat reserves.
SCALES
E. The only major country still using the Fahrenheit scale for temperature is the United States. The rest of the world and the scientific community use the Celsius scale which is part of the metric system. (Only if you want to learn how to covert from one to another there is a good scale and conversion factors on Figure 4.10 on p. 106.)
X SHORT-TERM VARIATIONS IN TEMPERATURE
DAILY EFFECTS OF INSOLATION--DAILY MARCH OF TEMPERATURES
A. Differences in temperature are caused by several factors, depending on how insolation is received or dissipated. Different places on the Earth receive different amounts of sunlight during the course of the year because of the declination of the Earth. Daily changes are caused by the rotation of the planet. As you know, insolation starts at dawn, reaches its zenith at solar noon, and stops and dusk. Perhaps you have noticed that usually the highest temperatures are in the early afternoon. The factor involved is not maximum insolation but when maximum of insolation is absorbed by the surface of the Earth and radiated back to the atmosphere. At night the heat stored during the day escapes and there is no heating of the atmosphere and reach their lowest point just before dawn. These temperature patterns can be plotted, (assuming no other factors are involved) and is called the daily march of temperature.
CLOUDS
B. Another factor in solar radiation is Atmospheric Obstruction. It is a technical term for two factors, the first is cloud cover and the second are the particulates in the atmosphere. According to weather satellites, 50 percent of the Earth's surface is covered with clouds. They are the most variable factor in temperatures. Clouds can diminish the amount of insolation and lower temperatures during the day, while at night they have an insulating effect and keep temperatures warmer. They are moderating influences on temperature. (Take a look at Figure 4.12 p. 108 and read the cutline.)
DIFFERENTIAL HEATING OF LAND AND WATER
MARITIME LOCATIONS AND CONTINENTAL LOCATIONSC. As mentioned in another section of the notes water heats and cools slower than land. (From time to time I may look like I'm repeating myself, but this is the nature of the material.) The air over the land or water is influenced by what is below it. Temperatures are moderated by bodies of water or those areas near them which receive westerly winds. Such locations are called maritime climates. (Where are maritime climates located in North America?) Summers are hotter and Winters are colder over the landmasses even if they are at the same latitude as a maritime location. This condition is called continentality. The concept is simple geography the further from the ocean the less the influence of maritime conditions. If you are looking for example reread the section on Controls of Weather and Climate on p. 8 of these notes or p. 96-7 of the text. (This is not the last time you will see this concept of maritime and continental climates.)
REFLECTION--ALBEDO
D. I've mentioned reflection in passing in an earlier section of these notes. The reflective quality of a surface is it albedo. Surfaces with a high albedo reflect a higher percentage of insolation back into space and do not take part in the heating process. As you may figure out this effects temperatures. Another important factor is its color. Dark objects have low albedos while than light colored ones have high albedos. The extremes of albedos can be seen in Colorado very easily. Snow and ice are good reflectors, and have albedos up to 95 percent. A forest has a albedo of about 10 to 12 percent. A city has a albedo of 10 percent and grass lands run about 10 to 25 percent. The albedo of water depends on the angle of the sun and can range from 2 percent to 90 percent.
HORIZONTAL AIR MOVEMENT
E. Remember how advection, the horizontal or lateral movement of air, is a major means of transfer of heat in the atmosphere. The same principle applies on the small scale as well. A movement of air can have short term effects on temperature. Sometimes in the midlatitudes large amounts of polar air can drop down and make temperatures drop dramatically.
XI VERTICAL DISTRIBUTION OF TEMPERATURE
A. It should be remembered that the atmosphere is warmed from the bottom up because of long-wave radiation, conduction and convection. As a general rule temperatures in the troposphere are usually higher at the surface while they decrease with elevation. As with many things in Geography there are exceptions to rules. In the first few hundred feet of elevation temperatures are variable. (Why are temperatures variable in first hundred feet of elevation?)
NORMAL LAPSE RATE--ENVIRONMENTAL LAPSE RATE
B. However, there is a general rule called the Normal Lapse Rate. It is only an average figure, other factors can come into play. The Lapse Rate is for every 1,000 feet in altitude the temperature decreases 3.6 Fš for every decrease in elevation it increases 3.6 Fš. (Just in case some people think in metric the Normal Lapse Rate is 6.4šC per 1000 meters or one kilometer.) One factor that could change the general rule is the air must be at rest. (Take a look Figure 4.13 on p. 109)
MATH QUESTIONS YOU CAN USE A CALCULATOR
I generally don't ask math questions, but since this is Colorado I thought this might be useful because there is over 10,000 feet difference between the lowest elevation in Colorado and the highest. I will pick a place and a given temperature and elevation then another place with elevation you will give me the temperature. This is almost like a bonus question but since math is involved it is scientific. (What is the lowest place in Colorado and what is the highest place. What are the approximate elevations.)
TEMPERATURE INVERSIONS
C. The most common phenomenon, which is the exception to the lapse-rate model are temperature inversions. A temperature inversion happens when the temperature increases with increasing altitude. The significance of a temperature inversion is that precipitation can decrease but a more important problem is air pollution is not dispersed, but hangs over an area like a deadly shroud.
UPPER AIR INVERSIONS
D. Some inversions take place three to six thousand feet above the surface of the Earth when a layer of warm air blocks the normal lapse rate. In inversions of this type the air is very stable (not moving up) and both precipitation and storms are prevented. Some upper air inversions are the result of air sinking from above and are called subsidence inversions. The air is compressed as it subsides and rises in temperature becoming more stable. (Take a look at Figure 4.14 on p. 110)
THE LOS ANGELES AREA
E. Another type of upper-air inversion is common in Southern California when cool marine time air comes in from the the Pacific and advances under the stable warm air. This type of inversion can last a long time. The cooler air can not rise, it is trapped by the warmer air, and the pollutants are trapped with it. This type of inversion is even worse in the Los Angeles area because the air is trapped not only from above but the mountains to the east make it difficult for the air to escape horizontally. (Take a look at Figure 4.15 on p. 110 and read the cutline.)
SURFACE INVERSIONS
F. One type of surface inversion is called a radiational inversion. They are consequence of rapid radiational cooling. This usually happens during winter nights when the land gives off long-wave radiation quickly. The land becomes colder than the air then cools the air above by conduction and radiation. Because there is only a short day for warming and a long night, they are more likely to happen in higher and mid-latitudes. Many times the condition is promoted by snow cover and advection of cool dry air into the area during calm air conditions. This problem occurs at cities high altitude cities like Denver, Colorado. This is the reason for high oxygen fuels that must be used during the winter months, Pueblo just misses by reason of altitude of being forced to use high-oxygen fuels. (Take a look at Figure 4.16 on p. 111)
COLD AIR DRAINAGE INVERSIONS
G. There is still another type of surface inversion it is a cold air drainage inversion. This development happens when cold air falls down a mountain slope into a valley dislodging the warm air. It is commonplace in some mid latitude areas. All one has to do is look at the San Luis Valley which is surrounded by mountains. The cold air stays there until the land warms up and can force the cold air out.
H. The example in your book discuss fruit trees along the Pacific Coast and how the crop can be decimated when a cold air drainage inversion is accompanied by frost. Fruit growers sometimes plant their trees on hill sides and avoid the valleys, but irrigation and the best soils are usually in the valleys. Sometimes they try to blanket the trees with straw, cloth, or some other form of insolation to replace water vapor. Fans are also used to stir the air and break-up the inversion,(Take a look at Figure 4.17 on p. 111.) In large operations orchard heaters are used, which have replaced smudge pots which put out a great deal of black heavy smoke. (In what area of Colorado would cold air drainage be a problem for fruit growers?)
XII TEMPERATURE DISTRIBUTION AT THE EARTH'S
ISOTHERMS AND TEMPERATURE GRADIENT
A. Temperature is displayed by isotherms, lines which link dots of equal value to form lines of equal temperature. As everyone in Colorado knows temperature varies because of altitude. It would be confusing if altitude was used to plot a global temperature map. Maps communicating global temperatures are qualified or modified maps. Data from these maps are figured as if the temperatures were at sea level by using the lapse rate, plus or minus 3.6 F, depending on increase or decrease of 1,000 altitude.The rate of temperature change on an isothermal map is called the temperature gradient. Lines that are close denote a steep gradient, (fast temperature changes over distance), it is the same principle as a contour map.
LATITUDE
B. Examine the two maps, (Take a close look at Figure 4.18 and Figure 4.19 on p. 112) these are global temperature maps. The maps indicate the high and low temperature extremes of summer and winter July and January. Even a rough glance at a world temperature map east to west the isotherms have a pattern. Take a look at these patterns approximated the lines of latitude running east to west. As could be expected the temperatures reflect the seasons highest temperatures are in July in the Northern Hemisphere and the lowest in January. It is reversed in the Southern Hemisphere with the highest temperatures in January and the lowest in July. The major factor in temperature is latitude because of the direct rays of the Sun. If we took a map which identified certain regions and overlayed it over the temperature map, we would find deserts at about the same places, or savannas, or polar areas but would be ball park figure, because of other factors in temperature.
SEASONAL PATTERNS
C. (Again take a look at Figure 4.18 and Figure 419 on p. 112) they show the latitudinal changes of isotherms, in short they reflect the changing seasons, and are amplified more in higher latitudes and over land. In short they shift north or south more over land and in high and mid-latitudes. Isotherm lines are closer, like elevation on a contour map, in winter than summer over the continents. The oceans show much less contrast, the lines are further apart, in both seasons.
LAND-WATER CONTRASTS
D. The isotherms in the maps are not straight seem to bend pole wards when they leave the continents. The reason the correlation between the heating and cooling of water and land-- Land-Water Contrasts. The landmasses are warmer in the summer and cooler in the winter, while temperatures over the oceans show little shift. The distribution of the land is also uneven, there is more of it in the Northern Hemisphere. Some of the noticeable changes in the isotherms exist near the coasts, where cool or warm ocean currents intensify other isotherms caused by land-water contrasts. The currents are diverted, warm currents head toward the poles, while cool currents flow to the equator. An example of warm currents modifying a climate is the Gulf Stream during Winter in the North Atlantic.
ANNUAL MARCH OF TEMPERATURE
E. The reason why isothermal maps are drawn using July and January temperatures is that there is a time lag of about a month from the solstices. The annual lag of temperature is comparable to the daily lag of temperatures. It takes some time for the Earth to cool or heat up after the solstices.
CLIMOGRAPHS
F. The yearly cycle of temperatures graphed from reports taken at weather stations. (Take a look at Figure 4.20 on p. 114 and compare to Figure 9.2 on p. 215) The first one does not have the precipitation on the bottom, but in all other ways they are identical except for the locations depicted. Geographers love maps, give them a chance they draw you a map. Climatologists whose who study climates, have the same type of love affair with Climographs. Climographs are charts showing average monthly temperatures, the range of temperatures and precipitation amounts. The text uses these Climographs a great deal, you might even get sick of them in the course of the chapter on climate.
GUIDED PRACTICE Questions during the lecture. INDEPENDENT PRACTICE Readings at home Culmination Does Temperature, Pressure, and the Why is the Atmosphere called an "Ocean of Air"? Composition of gases vary in the Atmosphere What are the two major gases in the Atmosphere ? Is there a Vertical Structure? The Particles in the Atmosphere what is there source How does the Atmosphere react to Solar Radiation and create Weather--Where does How does the Vertical Structure of the Atmosphere work give some examples? the heat come from? Solar Energy be broken down into radiation, conduction, convection, advection, latent heat of condensation--The Mechanisms for Heat Transfer. Describe each one and which ones are the most important? List the major elements of Weather and Climate? Does the Heat Energy Budget for the planet and how does it vary? What are the three forms of water, and what is latent heat? List the Short Term Variations in Temperature? The Atmosphere has a Vertical Temperature Range. What is the Normal Lapse Rate--Go figure. What are Inversions. Describe how TemperatureDistributed on the Earth's Surface? Delineate the Global Temperature Patterns and the Seasonal Patterns.?