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Energy Flow in Global Systems


Unit 4 Energy Flow in Global Systems Systems three types depending on their interactions with its surroundings. open system energy and matter can enter and leave. – PowerPoint PPT presentation

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Title: Energy Flow in Global Systems

Unit 4
  • Energy Flow in Global Systems

  • three types depending on their interactions with
    its surroundings.
  •  open system energy and matter can enter and
    leave. Ex a tree
  • closed system energy can enter and leave but
    matter can not. Ex the earth
  • isolated system neither energy or matter may
    enter or leave. Ex the universe

The Biosphere
  •   the layer around the earth in which living
    organisms are found
  •    three parts
  •   atmosphere air
  •   lithosphere land
  • hydrosphere water

  • is the process by which solar energy reaches
  • visible light reaches the Earths surface
  •   some of the visible light
  •    is absorbed heating the surface
  •   is reflected
  • the warmed objects on the surface emit infrared

Radiation continued
  • infrared radiation may be temporarily trapped in
    the atmosphere but eventually is lost to space
  •   Earth maintains an energy and temperature
    balance by radiating as much energy into space as
    it absorbs
  • dark surfaces absorb more energy and light
    surfaces reflect energy

Radiation continued
  • the reflectivity of a surface is called albedo
  •  the greenhouse gases in the atmosphere absorb
    infrared radiation keeping the surface warm
    during the night
  • the greenhouse gases include water vapour,
    carbon dioxide, methane, nitrous oxide, ozone,
    CFCs and HFCs

Climates and Seasons
  • climate is the trend in temperature, atmospheric
    pressure, humidity and precipitation over many
  • weather is these same factors at a certain time
    and place
  • the tilt of the Earths axis and the curvature of
    the surface result in differing amounts of solar
    radiation absorbed

Climates and Seasons cont
  • tilt of the Earth angle of inclination
    determines the length of day and night at
    different latitudes
  • the Earth travels around the sun in an
    elliptical orbit
  • for ½ the year we are tilted away from the sun
    and ½ the year we are tilted toward the sun

Climates and Seasons cont
  • the three main factors that affect heating at
    the surface are
  • 1. surface conditions - albedo
  • 2. tilt - seasons
  • 3. latitude angle of incoming solar radiation
  • (amount absorbed/reflected)

Specific Heat Capacity
  • is the amount of heat required to raise the
    temperature of 1 g of a substance by 1 ºC 
  • Q mc?T Q amount of heat (J)
  • m mass in g
  • c specific heat capacity (J/gºC)
  • ?T change in temperature (C)

Transfer of Energy
  • several mechanism of energy transfer play a role
    in heating the atmosphere
  • 1.   conduction transfer of energy from one
    molecule touching another
  • energy always moves from the warmer object or
    molecule to the cooler one

Transfer of Energy cont
  • 2.   convection air circulates and distributes
  • warm air is lower density than cooler air and so
    will rise and carry heat with it
  • 3.   radiation the greenhouse gases absorb the
    long wave radiation given off at Earths surface
  • all molecules will lose heat by radiation

Phase Changes
  • when a phase change occurs energy is gained or
    lost with not change in temperature
  • for example water at 0C loses energy in order
    to freeze
  • heat of fusion (Hfus)amount of energy required to
    melt one mole of a substance

Phase Changes cont
  • or the amount of energy lost to freeze 1 m of a
  • Q nHfus

Phase Changes cont
  • heat of vaporization(H vap) the amount of energy
    required to convert one mole of a substance from
    a liquid to a gas
  • the amount of energy lost convert 1 m of a
    substance from a gas to a liquid 
  • Q n Hvap

Unique Properties of Water
  • water has a high specific heat capacity ( 4.19
  • large amounts of heat has to be lost or gained
    to change the temperature of large bodies of
  • as a result bodies of water have a moderating
    effect on nearby land

Unique Properties of Water
  • water has a high heat of vaporization (40.68
  • water has a high heat of fusion (6.01 kJ/mol)
  • water expands when heated and contracts when
    cooled reaching its greatest density at 4 C

Unique Properties of Water
  • below 4 C water begins to expand resulting in
    ice that has lower density than liquid water
  • this explains why ponds and lakes freeze on the
    surface allowing aquatic organisms to survive the
    winter below the ice

Hydrologic Cycle
  • look at the diagram on page 386 and sketch in
    your notes
  • Work Pg 387 1-5

Distributing Heat - Oceans
  • oceans are large heat reservoirs
  • water has low albedo and absorbs more than 90 of
    the solar energy striking it
  • oceans cover 70 of the Earths surface
  • ocean currents carry warm water to different
    latitudes affecting coastal areas and influencing
    worldwide climate Gulf Stream which becomes the
    North Atlantic Drift

Distributing Heat - Oceans
  • Gulf Stream is part of a global ocean current
    called the thermohaline circulation or Great
    Ocean Conveyor Belt
  • El Nino Southern Oscillation (ENSO) is a
    disruption of the ocean-atmosphere system
  • occurs every 3 to 7 years

Distributing Heat - Oceans
  • during El Nino the wind direction over the south
    Pacific reverses
  • read pg 389-390
  • La Nina causes an increase in strength of the
    normal patterns of westward moving winds

Patterns of Wind Movements
  • low pressure occurs as warm air expands becoming
    less dense and rises
  • high pressure occurs as cold air contracts,
    becomes denser, and descends
  • a convection current is created when warm air
    rises at one location cools and contracts sinking
    to the surface at another location

Patterns of Wind Movements
  • there are actually three separate convection
    currents in each hemisphere
  • warm air rises at the equator and sinks at 30 (N
    and S)
  • warm air rises at 60 (N and S) and sinks at the

Patterns of Wind Movements
  • convection currents veer sideways from their
    original path due to the rotation of the Earth on
    its axis this is called the Coriolis Effect
  • this creates
  • 1. Polar Easterlies
  • 2. Prevailing Westerlies
  • 3. Northeast Trade Winds
  • 4. Doldrums quiet area of little winds

Jet Streams
  • are currents of extremely fast-moving air about
    10-15 km above the Earths surface
  • flow from west to east
  • form at boundaries of warm and cold air
  • intense winds in the jet stream influence
    precipitation and thunderstorms

Oceans and Mountains
  • sea breezes are formed when in the morning the
    sun warms the land before the water and the air
    over the land rises and over the water the cool
    air sinks creating a convection current

Oceans and Mountains
  • land breezes are formed in the evening when the
    water stays warmer longer so now the warm air
    rises over the water and sinks over the cooling
    land again creating a convection current
  • Prevailing Westerlies bring warm moist air
    onshore in BC, as this air is forced to rise
    higher to get over the mountains the air cools,
    the moisture condenses and falls as precipitation
    orographic precipitation

Oceans and Mountains
  • the cool dry air moves down the eastern side of
    the mountains warming up due to the increase
  • little rain occurs here in the rain shadow
  • in the winter this warm westerly wind is called a
    Chinook (snow eater) as it melts and evaporates
    or sublimates the snow as it goes

  • temperature is a critical element in defining
  • altitude is also important temperature drops
    4.5 ºC for every kilometre increase in altitude
  • humidity is the amount of water vapour in the air

Climate continued
  • at higher temperatures more water molecules have
    enough kinetic energy to exist as a vapour
  • if the humidity is low organisms dry out
  • the temperature at which water condenses and
    begins to fall as rain or snow is called the dew

  • is a graphical representation of climate data for
    a specific region and time period
  • includes average monthly temperature and total
    monthly precipitation
  • do investigation 11-A page 405

  • can be defined as a major geographic region with
    similar environmental conditions and life forms
  • freshwater and ocean or aquatic biomes dominate
    the biosphere
  • 6 distinct terrestrial biomes will be examined
  • look at page 407

Adaptations and Biomes
  • an adaptation is any characteristic that enables
    an organism to better survive and reproduce in an
  • 1. physiological adaptations occur inside an
    organism, eg the changes when animals hibernate
  • 2. structural adaptations physical features of
    an organism, eg fur for warmth

Adaptations and Biomes
  • 3. behavioural adaptations things the organism
    does to survive, eg migration
  • Using your text book make notes on the 6
    terrestrial biomes

  • is the study of past climates
  • Geological Survey of Canada has completed
    reconstructing Canadas Paleoclimate from 6000
    years ago
  • they discovered the vegetation zones

  • causes of natural climate change
  • o  Earths tilt
  • o  Earths orbit
  • o   continental drift
  • o   weathering (breaks rocks into smaller pieces)
  • o   catastrophic events meteors, volcanoes
  • feedback

  • rapid climatic changes sometimes resulted in
    mass extinctions
  • slower climatic changes may explain animal
    migrations, evolution of physical
    characteristics, changes in diet, decreases in
    populations and forests moving north and south