1Chapter 2Heating Earth’s Surface and AtmosphereI. Earth–Sun RelationshipsA. Earth’s 2 Principal Motions1. Rotation : spinning about the axis2. Revolution : orbit around the sunPDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com2Revolutiona. Perihelion :earth closest to sunb. Aphelion :earth farthest from sunB. The seasons- result from variations in the intensity (or amount) of solar radiation striking the earth-Height of noon sun changes-Length of day changesPDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com3Sun Angle-influence intensity of solar radiationSun Angle-influence distance traveled through atmospherePDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com4C. Earth’s Orientation1. Plane of the ecliptic = plane of earth’s orbit around the sun2. Inclination of the axis = tilted 23.5 degreesC. Earth’s OrientationCircle of illuminationPDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com5D. Solstices and equinoxesCircle of illuminationPDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com6Temperature Data at Different Latitudes- annual temperature range increases with latitude- earth-sun geometry is not the only controlII. Energy, Heat, and TemperatureUniverse = composed of matter and energyEnergy = the capacity to do work (move matter)A. Forms of energy1. Kinetic energy: energy of motion (1/2 mv2), atomic level2. Potential energy: potential to do work (ρρρρgh)PDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com7II. Energy, Heat, and TemperatureB. Temperature: a measure of the average kinetic energy of the atoms or molecules in a substance- Fahrenheit, Celsius, and Kelvin (-273)C. Heat: refers to the transfer of energy between substances due to temperature differences- heat flow stops when temperatures are equalIII. Mechanisms of Energy TransferA. Conduction: transfer of heat through electron and molecular collision- poor conductors = insulators- air = poor conductor- metal = good conductorPDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com8III. Mechanisms of Energy TransferB. Convection: heat transfer involving movement or circulation of a substance (liquids & gasses)- thermals = convective cells in atmosphere- convection = up-down movement- advection = horizontal movementConvection Cell ExamplesPDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com9III. Mechanisms of Energy TransferC. Radiation: energy emitted in the form of waves or particles Solar Radiation = electromagnetic radiation- self-propagating wave that can travel through the void of space - classified into types according to the wavelengthPDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com10electromagnetic radiation- order of increasing wavelength: gamma rays, X-rays, ultraviolet radiation, visible light, infrared radiation, microwaves, radio waves2. Laws of radiation- All objects continually emit radiant energy over a range of wavelengths- Hotter objects radiate more total energy per unit area than do colder objectsStefan-Boltzman LawE = σσσσT4σ = 5.67x10-8W/m2K4Sun = 6000 K Earth = 300 KE(S)= 73,483,200 W/m2E(E) = 459 W/m2PDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com112. Laws of radiation- The hotter the radiating body, the shorter the wavelength of maximum radiationWien’s Displacement Lawλλλλmax= C/T C = 2898 µmKλλλλsun= 0.483 λλλλearth= 9.662. Laws of radiation- Objects that are good absorbers of radiation are also good emittersBlackbody = 100% efficientAtmospheric Gasses = selective absorbersPDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com12III. What Happens to Radiation?- absorbed = observed increase in kinetic energy- transmitted = transparent to solar radiation- redirected = reflection and scatteringA. Reflection and scatteringdiffused light = scattered solar radiationalbedo = fraction of radiation that is reflected by a surfacePDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com13Scattering & Diffused LightCrepuscular raysIV. Radiation Emitted by EarthA. Earth radiates energy as a longwave (infrared band, 95%)B. Selective absorption by gassesPDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com14The Greenhouse EffectCO2H2OC. Role of clouds in heating Earth-clouds at night absorb infrared radiation and re-radiate it back to surface-low thick clouds during the day reflect solar radiation, cool the surfacePDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com15V. Heat BudgetVI. Latitudinal Heat Balance PDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com16Electromagnetic radiation is generally described as a self-propagating wave in space with electric and magnetic components. These components oscillate at right angles to each other and to the direction of propagation, and are in phase with each other. Electromagnetic radiation is classified into types according to the frequency of the wave: these types include, in order of increasing frequency, radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays. In some technical contexts the entire range is referred to as just 'light Classically, the electromagnetic field is a physical influence (a field) that permeates through all of space, and which arises from electrically charged objects and describes one of the four fundamental forces of nature - electromagnetism. It can be viewed as the combination of an electric field and a magnetic field. The electric field is produced by non-moving charges and the magnetic field by moving charges (currents); these two are often described as the sources of the field. PDF Created with deskPDF PDF Writer - Trial ::