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Unit One GG101 Notes w/ Study Quiz

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Wilfrid Laurier University
William Bill Quinton

Part I: The energy-atmosphere system Part I_2 What controls strength of sun waves? Distance of the sun. earths revolution around sun and its tilt, atmosphere filtering effect. Solar Constant Solar constant of 1400 w/m once sun rays get to earth Equinox position:  Everywhere has 12 hours of day and 12 hours of night  When sun sees both poles at same time  Sub solar point at equator  Happens twice in a year. Fall and spring  Equal amount of light hitting north and south. North=south Winter solstice:  Sub solar point is the condition of the earth where sun is directly over head.  90 degrees over on horizon.  Axis line is 23.5* north of light  24 hour darkness in North  Sub solar point 23.5* south of equator Summer Solstice  Sub solar point Is 23.5* north of equator  24 hour darkness in South Geometric positions are important because they control position of sub solar point and therefore angle of indication. Angle of incidence is important because energy from sun is diluted in low angle positions and less diluted in high angle positions. Tilt of the axis causes seasons. Seasons are effective way of distributing energy. If no tilt than we would have hotter equator and colder poles. Sun degree is 26* during Winter, 50* during Spring, fall and 73* during Summer solstice. Time of day/year (Check slides for graph) What Controls Angle of Incidence? Latitude, time of day, time of year Solar Energy to Earth and the Seasons How  does  solar  radiation  flow  through  Earth’s  atmosphere? 1. Nature and forms of radiation Wavelength is a measure of solar radiation. - Long wave and short wave 2. Laws governing energy flows Energy is in equilibrium. Moves from surplus to deficit Rate of energy movement is proportional to energy gradient. Energy moves through colder things faster Energy cannot be created or destroyed (conservation of energy) I= t+a+ α 3. Laws Describing Radiation from surfaces The Electromagnetic Spectrum Long waves are in lower half. Short waves are top half. Both can be broken down into components. Short wave is the light that we can see. 1) Inverse relationship between temperature of an object and wavelength it emits Weins’  Law:  (Delta)max  =  b/T b is constant  and  T  is  surface  temperature.  b  =  2898,  T  =  temp  [K]…  kelvin Explains horizontal difference in graph 2) Flow of radiant energy from a surface is directly related to the surface energy to the fourth power. Increase temperature of the surface a little bit, you increase the temperature of radiation by a lot. The wavelength of maximum intensity radiation grows longer as the absolute temperature of the radiating body decreases. 4 Stefan-Boltzman law: M = σT Explains vertical difference in graph 4. Budgets of radiation and energy Earth’s  atmosphere  transmits,  absorbs  and  reflects  the  suns  energy  (t+a+α) Atmosphere  is  an  “energy  filter” With filter 1400 w/m square radiation but around 500 is transmitted. If no filter than all is transmitted Filter causes radiation to be transmitted, absorbed or reflected. The ground does the same thing. Depends on ground properties. Ex. Snow has better reflective properties than asphalt. Atmosphere also varies. About 10000km deep, 97% within ground and 30km above.  78% nitrogen  21% oxygen  1% argon, Carbon Dioxide, Water vapour Green house gasses (absorb long waves). Increase the absorption of energy and warms atmosphere.  Warm air  Photosynthesis – respiration  Vary in concentration  Combustion If  there  is  an  increase  in  ‘a’,  than  temperature is going to rise. How  does  “atmospheric  filter”  vary  with  time? Clouds can cause absorption of 5-20% and reflection of 35-60%. So only 45-10% reaches the ground. Filter is not a constant thing, but is more dynamic. Atmospheric filter: - reduces by absorbing and reflecting energy - It also transforms absorbed short wave energy into long wave energy. If reflected it stays short wave. - It also scatters energy. Direct and diffuse. I= T+a+alpha - ‘Alpha’  is  reflected  energy  that  stays  short  wave.    Diffuse  if it reflects off something in atmosphere and doesn’t reach the ground. - ‘t’  is  Direct  energy  that  makes  it  through  atmosphere  to  ground. - ‘a’  is  energy  that  is  absorbed  and  reemitted  as  long  wave.  Greenhouse  gasses  are  good  at   absorbing the long wave energy. GG101 Lecture part 1_3: Radiation and Energy Balances Albedo Albedo (α): Ratio of the amount of radiation reflected by a body to the amount incident upon it. Varies according to colour of surface. Bright surfaces are good reflectors such as snow. Transmission varies. Over opaque surface is low but on water surface it can be up to 50%. If good reflector  than  you’re  a  bad  absorber.  Inverse  relationship. Incoming is downward directed arrow. Outgoing is upward directed arrow. Net all-wave radiation (radiation balance) – Q* = (S˅ – S˄) + (L˅ – L˄) Q* = S* + L* = 100 units S is short wave, L is long wave. Energy balance: Q* = Qe+Qh+Qg Qe - This part of the energy balance changes the phase of water. Latent heat flux. Latent heat causes evaporation. Latent heat is the heat released or absorbed by a chemical substance or a thermodynamic system during a change of state that occurs without a change in temperature, meaning a phase transition such as the melting of ice or the boiling of water. Latent heat flux: the flux of heat from the Earth's surface to the atmosphere that is associated with evaporation or transpiration of water at the surface and subsequent condensation of water vapour in the troposphere. Qh - Goes to heat the air above the ground. Sensible heat flux. Molecular conduction – Energy transferred from particle to particle. Molecular convection – Movement of the heated particles or molecules. Heat that goes to warming up the air. Qg – goes vertically downward to heat the ground below the surface. Ground heat flux. Conduction and occasionally convection with moving water. Phase Changes of Water Release latent heat. Absorb latent heat: Takes energy out of something like taking money from a bank. Sublimation is solid to vapour. That is why sublimation is evaporation and melting added. Day-time & Night-time Fluxes During night time there is only long wave. During day time you must incorporate short and long. Evaporation is pointed upwards because its making energy away from balance. Day: Energy is directed away from surface. During day there is +deltaQ. Flux convergence when +deltaQ Night: More energy going away from ground than into ground. Reverse form day. Energy is going back. During night there is -deltaQ. Flux divergence when -deltaQ To have evaporation you need energy and water. So does not work in deserts. At a farm Qe term is dominant because energy is being put into evaporation. Partitioning of Solar Radiation Q* = 48 + (-16) Different ground surfaces heat up air above it differently. Part 1_4: Global Temperatures Profile of the Atmosphere Temperature changes throughout the atmosphere Atmospheric Composition Heterosphere – outer atmosphere - From 80km and above: same as thermosphere - Layer of gasses. Sorted by molecular weight of gas molecules Homosphere – inner atmosphere - Surface to 80km - Gasses evenly blended Atmospheric Pressure Less pressure as you go up the atmosphere – molecules are farther apart as you go up. - Starts at 1000 millibars and goes to zero as it goes higher. - 1000-175 Millibars in troposphere, 175-0.78 in stratosphere, 0.78- 0.0
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