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Geo%20D%20Unit%206%20Lecture

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Geo D Unit 6 Lecture Chapter 11 pages 271-282, all of Chapter 12, and Chapter 14 pages 559-363 and pages 370-377 – PowerPoint PPT presentation

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Title: Geo%20D%20Unit%206%20Lecture


1
Geo D Unit 6 Lecture
  • Chapter 11 pages 271-282, all of Chapter 12, and
    Chapter 14 pages 559-363 and pages 370-377

2
CHAPTER 11 PAGES 271-282
3
Key Atmospheric Gases
  • The atmosphere is made up of many gases
  • 99 nitrogen and oxygen
  • Water vapor and carbon dioxide determine
    temperature
  • Particulates are solids floating around in the
    air that water vapor can condense on

4
Ozone
  • 3 oxygen molecules bonded together
  • Located in the stratosphere
  • Absorbs UV rays and protect us from the sun

5
Layers of the Atmosphere
  • Troposphere- closest to Earth, where most of the
    weather occurs, gets colder as your go higher
  • Stratosphere- contains ozone, gets warmer as you
    go higher
  • Mesosphere- very few molecules, coldest layer,
    gets colder as you go higher
  • Thermosphere- hottest layer, gets hotter as you
    go higher

6
  • Beyond the thermosphere is the exosphere which
    leads us into space

7
Solar Fundamentals
  • Radiation
  • The sun radiates onto Earth
  • 50 absorbed by the surface
  • 15 absorbed by atmosphere
  • 25 reflected from clouds back into space
  • 4 reflected by surface back into space
  • 6 reflected by atmosphere back into space

8
  • Conduction
  • Transfer of heat to solids
  • Done by contact
  • Convection
  • Transfer of heat to liquids and gases
  • Creates convection cells in the atmosphere

9
Temperature verses Heat
  • Temperature
  • Measure of the average kinetic energy of
    molecules
  • Heat
  • Transfer of energy because of a difference in
    temperature
  • Moves from high to low

10
Measuring Temperature
  • In the United States we use Fahrenheit
  • For science class we will use Celsius or Kelvin
  • To convert from Celsius to Kelvin, simply add 273
  • 0 C 273 K (freezing point of water)
  • 100 C 373 K (boiling point of water)

11
Dew Point
  • Dew point is the temperature when air reaches
    saturation
  • Once dew point is reached, condensation happens
    (water vapor forms into water drops)

12
Vertical Temperature Changes
  • In the troposphere, temperature decreases as
    elevation increases
  • Cooling of 10 C for every 1000m increase
  • This is the dry adiabatic lapse rate
  • The height at which condensation occurs is called
    the lifted condensation level (LCL)
  • Above the LCL, air cools more slowly

13
Air Pressure and Density
  • The density of air is proportional to the number
    of particles present
  • The density of air decreases as you move from the
    crust out into the atmosphere

14
Pressure Temperature Density Relationship
  • Temperature is directly proportional to pressure
  • Temperature decreasespressure decreases
  • Ex Moving higher up Mt. Everest
  • Pressure and density also directly proportional
  • Pressure decreasesdensity decreases

15
Temperature Inversions
  • An exception to the rule that pressure and
    temperature decrease with height in the
    troposphere is an inversion
  • Commonly happens when cities are in a basin and
    pollution becomes trapped there

16
Wind
  • Caused by unequal heating of the earths surface
  • Cool air sinks, warm air rises and allow for
    areas with differences in air pressure
  • Wind speeds increase with altitude because there
    is less friction with objects and the earth

17
CHAPTER 12
18
Meteorology
  • Meteorology is the study of atmospheric phenomena
  • Hydrometeors are the items that contain water
    like clouds, rain, fog, etc
  • Lithometeors are condensation nuclei like smoke
    and dust
  • Electrometeors are the items that are a visible
    or audible manifestation of electricity like
    thunder and lightning

19
Weather verses Climate
  • Weather
  • Current state of the atmosphere
  • Short term
  • Climate
  • Long term variations in weather for a particular
    area

20
  • The continual motion of air and water reallocates
    heat energy among Earths surface, oceans, and
    atmosphere and helps keep balance

21
Air Masses
  • Air masses are large bodies of air over a certain
    area
  • Those that form over land are drier than those
    over water

22
  • Warm and dry cT continental tropical
  • Warm and humid mT maritime tropical
  • Cold and dry cP continental polar
  • Cold and humidmP maritime polar
  • Arctic A
  • All 5 air masses can be found in N America
  • Modification happens when they move away from
    their source regions

23
Weather Systems
  • The Coriolis Effect is the deflection of air to
    the right in the N Hemisphere and to the left in
    Southern
  • Caused by the rotation of the earth

24
Global Wind Systems
25
  • At the equator are the doldrums where ships would
    become stranded due to weak winds
  • Trade winds occur above and below the equator
  • Moves to the west
  • Also known as the Hadley cell

26
  • Between the trades and the westerlies is a calm
    belt with weak winds called the horse latitudes
  • Boats become stranded here
  • The prevailing westerlies blow to the east
  • The polar easterlies blow to the west

27
Jet Streams
  • Jet streams are narrow bands of fast, high
    altitude winds
  • Move up to 185 km/h
  • Two main jet streams
  • 1. polar jet stream
  • 2. subtropical jet stream

28
Fronts
  • A front is a narrow region separating two air
    masses of different densities
  • Their interaction brings dramatic changes in the
    weather
  • 4 types of fronts
  • 1. cold front
  • 2. warm front
  • 3. stationary front
  • 4. occluded front

29
Cold Front
  • Cold, dense air displaces warm air
  • Forces the air up along a steep front
  • Clouds, showers, sometimes thunderstorms
  • Drawn as a solid blue line with solid blue
    triangles

30
Warm Front
  • Advancing warm air displaces cold air
  • Develops a gradual frontal slope
  • Extensive cloudiness and precipitation
  • Drawn as a solid red line with solid red
    semicircles

31
Stationary Front
  • Small temperature and pressure difference between
    two air masses
  • The boundary between them stalls
  • Mild weather patterns
  • Drawn as a combo of warm and cold front symbols

32
Occluded Front
  • Cold air moves so fast that it wedges warm air
    upward
  • That cold air collides with an advancing cold
    front
  • Precipitation is common
  • Drawn as alternating purple triangles and semi
    circles

33
Pressure Systems
  • High Pressure
  • Air moves outward in a clockwise direction in N
    Hemisphere
  • Fair weather
  • Low Pressure
  • Moves inward in a counter-clockwise direction in
    N Hemisphere
  • Clouds and precipitation

34
Gathering Weather Data
  • Thermometers measure temperature
  • Barometers measure air pressure
  • Anemometers measure wind speed
  • Hygrometer measures humidity
  • Ceilometer measures the height of the clouds

35
  • Radiosonde measures temperature, air pressure,
    and humidity
  • Sends radio signals back to the ground station
    from heights of 30,000m

36
Doppler Radar
  • The Doppler effect is the change in frequency
    based on movement towards or away from the
    observer
  • Doppler radar plots the speed that raindrops
    moved toward or away due to wind

37
Weather Satellites
  • Weather satellites use both visible light and
    other forms of radiation to observe the
    atmosphere
  • Infrared satellites detect changes in thermal
    energy
  • Allow scientists to determine the temperature of
    a cloud to determine its type and height

38
Weather Analysis
  • A station model is a record of weather data for a
    particular site at a particular time
  • Isopleths are lines that connect points of equal
    values
  • Temperature isotherms
  • Pressure isobars, closer together are stronger
    winds

39
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40
Forecasts
  • Short term
  • Digital forecasts
  • Done by high speed computers
  • Uses numerical data
  • Analog forecasts
  • Use past events
  • Long term
  • Less accurate
  • Less detailed
  • Vague
  • Used more for seasonal forecasts

41
CHAPTER 14 PAGES 359-363 AND 370-377
42
Climate
  • Climate describes the long term weather patterns
    of an area
  • Variations in temperature, precipitation, wind,
    etc

43
  • Data is such as daily high and low temps,
    rainfall, wind speed and direction, humidity, and
    air pressure is collected
  • Averaged on a monthly or annual basis for 30
    years
  • This determines the normals (standard value)

44
Causes of Climate
  • 1. latitude
  • The closer to the equator, the more direct the
    suns rays hit and therefore receives more solar
    radiation

45
  • 2. topography
  • Closeness to lakes and oceans
  • Warmer in winter and cooler in summer than inland
    areas
  • Mountain climates cooler than sea level
  • Windward side of mountains are wet and cool,
    leeward side is dry and warm

46
  • 3. air masses
  • Warm and dry cT continental tropical
  • Warm and humid mT maritime tropical
  • Cold and dry cP continental polar
  • Cold and humidmP maritime polar
  • Arctic A

47
Short term climate changes
  • Seasons are short term periods of climate change
    caused by variations in daylight, temperature,
    and weather patterns

48
El Nino
  • El Niño is a warm ocean current that develops off
    the western coast of S America
  • When the high pressure system and its trade winds
    weaken, changes in weather occur
  • Causes stormy weather to normally dry places and
    drought conditions to normally wet

49
Natural Changes to Climate
  • 1. solar activity
  • The suns sunspot cycles last about 11 years
  • A period of low sunspot activity is called a
    Maunder Minimum, causes colder temperatures

50
  • 2. Earths orbit
  • Earths orbit becomes more elliptical then more
    circular and so on back and forth
  • When the orbit elongates, the earth is closer to
    the sun, and temperatures become warmer

51
  • 3. Earths tilt
  • Angle varies from 22.2 degrees to 24.5 every
    41,000 years
  • Differences in angle could cause seasons to
    become more severe

52
  • 4. Earths wobble
  • By the year 14,000 Earths axis will point toward
    the star Vega instead of Polaris
  • This will cause more extreme seasons

53
  • 5. volcanic activity
  • When volcanoes erupt, they send out immense
    quantities of dust into the atmosphere which
    blocks incoming solar radiation

54
The Human Factor
  • The greenhouse effect allows for life to survive
    on earth, because a small portion of radiation is
    not allowed to reflect back into space
  • This effect is impacted by the amount of
    greenhouse gases in the atmosphere
  • These include carbon dioxide, methane, and water
    vapor

55
Global Warming
  • Temperatures have increased over the past 200
    years
  • This warming is causes a melting of the polar ice
    caps
  • This would then causes a rise in sea level
  • Scientists are not all in agreement about what is
    causing global warming
  • Most blame our carbon dioxide output due to
    burning fossil fuels
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