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Lecture

GG.docx

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Department
Geography
Course Code
GG101
Professor
Bina Mehta

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Description
Week#2 (first class) Jan.15th Great circle: any circle which divide circle into two equal half. a plane interacting the globe along a great circle divides the globe into equal halves and passes through its center. Small circle: a plane that intersects the globe along a small circle splits the globe into unequal sections-this plane does not pass through the center of the globe. 20°W(0 o'clock) and 160°E(12o'clock) was designed for the time zone. (non-standard time) time increase from the left to the right in Canada, the standard time is New fenland time Modern international time zones  national boundaries and political considerations distort time boundaries. Map, Scale and Projections  map - a generalized view of an area, as seen from above and reduced in size  scale - ratio of map units to ground units  projection - process of transforming spherical Earth to flat map The scale of maps 1:250 000 ( one centimeter = 2.5 kilometres) three common expressions of map scale--representative fraction, graphic scale 图示比例尺, and written scale. [written scale: one centimetre equal 2.5 kilometres] Projecting a Globe on to a Flat Map Map projection (Mercator projection-cylindrical) when we convert from a globe to a flat map. in this example we fill in the gaps at high latitudes. on the map, this makes the land areas at high latitudes look larger than they actually are, distorting distance. In this projection we do not even see land above the 80th parallel because there is too much distortion. Mapmaker cut it off. Great circle routes a) gnomonic projection b) Mercator projection(conformal, true shape) -- accurate Great circle-shortest distance between two points  does not maintain constant direction Rhumb line- line of constant direction  also known as a loxodrome, not the shortest distance between two points. Remote Sensing 遥感 Active remote sensing  The instrument sends out its own energy, which is reflected back to it  most common: Radar, Lidar Passive remote sensing  The instrument receives reflected solar energy or emitted energy  most common: visible light, near and middle infrared energy, thermal energy Week#2 (second class) Jan.17th The Solar System, Sun, and Earth --Solar system formation and structure  Gravity地心引力 - mutual attracting force exerted by mass 質量 on all other objects [the further distance, the less gravity]  planetesimal 小行星體 (dust-cloud) hypothesis 星子假說 - suns condense from (凝結) nebular星雲 clouds  proto-planets accumulated in eddies within nebula [八大行星]  energy travels outward from sun to planets Dimensions and distances  Light is one form of energy received from the Sun  Can use speed of light as a measure of distance - 299792 kilometres per second (about 300000km/s) - Milky Way Galaxy 100000 light-years across - Our Solar System 11 light-hours across - Our Moon is 1.28 light-seconds away  Earth's orbit 軌道 - Average distance from Earth to the Sun is 150000000 km in an eliptical orbit - Perihelion (closest distance in our orbit) - closest at January 3, 147225000 km - Aphelion (farthest distance in our orbit) - farthest at July 4, 152083000 km - Earth is 8 minutes 20 seconds from the Sun at the speed of light - Plane of Earth's orbit is plane of the ecliptic(黃道面) [the angle of plane of the ecliptic and equatorial plane 赤道面 is 23 °26 ′] Solar Energy: From Sun to Earth  Solar Wind(太陽風:太陽表面放射離子組成的離子流) is comprised of clouds of electrically charged particles  Sunspots are caused by magnetic storms on the Sun  Sunspots activity cycle of about 11 years  Coronal mass ejections 日冕物質拋射 send matter from the Sun out into space Aurora Australis and Aurora Borealis For up to date information on solar flaresy 耀斑 and solar wind see http://astronomynorth.com/aurora-forecast/ or http://spaceweather.com/ Wavelength and Frequency 波長和頻率  the shorter the wavelength, the higher the frequency Energy travels in waves Electromagnetic Spectrum of Radiant Energy -visible light -- red(0.647-0.710), orange(0.585-0.647), yellow(0.575-0.585), green(0.491-0.575), blue(0.424-0.491), violet(0.400-0.424). [micrometers] 0.4-0.7 all six colors mix together will become white. X-Ray use for medication All of them come from the Sun Week#3 (first class) Jan.22nd Electromagnetic Spectrum of Radiant Energy  Wavelength of radiated energy depends on the temperature of the radiating body (Stefan- Boltzmann law) - Sun is hotter, so radiates shorter wave energy, mainly visible and near infrared Solar and Terrestrial Energy To describe the Sun -- 6000k blackbody radiation To describe the Earth -- 273k balckbody radiation 12-15 degrees -- the temperature of the earth and get warmer Earth wave length wave energy Sun waves short wave energy some of the energy absorption by - oxygen and ozone - water vapour and carbon dioxide - carbon dioxide, water and other radiatively active gases Earth's Energy Budget Earth output waves are wave-longer than Earth incoming waves. INPUT Solar radiation to Earth Concentrated in shorter wavelengths OUTPUT Uneven Distribution of Insolation 太陽直射  Tropics receive ore concentrated insolation(energy per unit area) - Due to Earth's curvature  Tropics receive 2.5 times the amount received at the poles Oblique斜照 Direct 直射 Daily Insolation at the Top of the Atmosphere 南北極圈,南北半球,赤道部分受日光照射不均 Global Net Radiation 全球淨輻射 incoming minus outgoing -- balance North Pole and South Pole: all negative The Seasons  Seasonality - Sun's alttude - angle above horizon - Declination - location of the subsolar point 太陽直射點位於南回歸線,為冬季,日照時間短 太陽直射點位於北回歸線,為夏季,日照時間長 太陽直射點位於赤道附近,為春或秋季,日照時間均為 12h - Variations in Daylength  Reasons for Seasons - Revolution 公轉 a) Earth revolves around the Sun b) Boyage takes one year(actually 365.24 days) c) Earth's speed is 107 280 km/h - Rotation 自轉 a) Earth rotates on its axis once every 24 hours b) Rotational velocity at equator 1674 km/h(40 075 km long) c) Rotational velocity diminishes with distance north and south of the equator (rotational velocity reduced to 838 km/h at 60°N, 20038 km long) - Tilt of Earth's axis a) Axis is the tilted 23.5° from plane of ecliptic - Axial parallelism a) Axis maintains alignment during orbit around the Sun b) North Pole always points toward the North Star (Polaris) - Sphericity - same as stated earlier with the concentration of energy at the equator and spread at the higher latitudes.  Annual March of the Seasons December 21-22 Winter solstice 23.5°S March 20-21 Vernal equinox 0° June 20-21 Summer solstice 23.5°N September 22-23 Autumnal equinox 0° Week#3 (Second class) Jan.24 Earth's Modern Atmosphere  Atmospheric Composition, Temperature, and Function - Atmosphere extend to 32 000 k from surface - Can be divided into shells (layers) by 1. Composition (divide to 2) 2. Temperature (divide to 4) 3. Function (divide to 2) most important  Atmosphere Layers  Each layer called a "sphere" ex. Atmosphere Profile Atmospheric Pressure way to measure the atmosphere right out of space. (Millibar--mb)  Variable Atmospheric Composition N₂ O₂ Ar CO₂ Week#4 Jan.29 Atmosphere Temperature  Thermosphere 熱大氣層  from 80 km outwards  roughly same as heterosphere  Mesosphere中間層  50-80 km altitude  Stratosphere 同溫層/平流層  18-50 km altitude  Troposphere 對流層  surface to 18 km  Contain 90% of the mass of atmosphere  temperature changes with altitude  environmental lapse rate -- actual local rate of cooling with altitude  normal lapse rate -- cooling at rate of 6.4℃ /km  Average of environmental lapse rates for many areas Temperature Profile of the Troposphere deceasing temperature with increasing altitude Atmospheric Function  lonosphere  altitude of thermosphere and mesosphere  Absorbs cosmic rays, gamma rays, X-rays, some UV rays  Ozonosphere  Within stratosphere  Ozone(0₃) absorbs UV energy and converts it to heat energy Variable Atmospheric Components  Natural Sources  Natural Factors That Affect Air Pollution  Anthropogenic Pollution  Carbon monocide  Phorochemical smog  Industrial smog and sulfur oides  Particulates Week#4 (second class) Jan.31 1372 W/m² -- Chapter 4 : Atmosphere and Surface Energy Balances  Energy Essentials  Energy Pathways and Principles
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