GEOG 1414 Chapter 1-3 Notes
GEOG 1414 Chapter 1-3 Notes GEOG 1414
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This 6 page Class Notes was uploaded by Megan Hanson on Wednesday March 2, 2016. The Class Notes belongs to GEOG 1414 at University of Minnesota Duluth taught by Tongxin Zhu in Spring 2016. Since its upload, it has received 28 views. For similar materials see Physical Geography in Geography at University of Minnesota Duluth.
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Date Created: 03/02/16
1/14/16 Physical Geography is a combination of atmosphere, hydrosphere, lithosphere, and biosphere. CHAPTER 1 Shape of the earth: Oblate ellipsoid – not a perfect sphere: ns 7900miles and ew 7926miles Earth’s Rotation: Solar Day – one complete rotation (with respect to the sun) = 24hours Rotation direction must have reference o View from space above north pole – counter clockwise o View from space above equator – from left to right Location and Time on Earth: Latitude and Longitude Prime Meridian – passed through Greenwich, England Converting degrees, minutes, and seconds to decimal degrees: o 41 degrees, 27 minutes, 41 seconds = 41+27/60+41/3600 = 41.4614 degrees Maps, Scales, and Map Projections: Cartography – the science of map making Scales = the map distance/the actual distance o Written Scale: a sentence – 1cm to 1km o Representative Fraction (RF): 1:125 or 1/125 o Graphic Scale/Bar Scale: Requires a ruler to measure Still Void even if the map is enlarged Map Projections – drawing the curved earth on a flat paper requires conversion and always involves distortion o 1. Cylindrical Projection o 2. Cone o 3. Plane – ex. Polar projection o Different projections involve different distortions o Shape, Area, and Direction should be considered – selection of projection should be based on particular applications so that the distortion is minimalized and the key property is preserved. Global Time: There are 24 time zones each about 15° Time zones follow pre existing natural or political boundaries Some have ½ hour differences (Newfoundland) International Date Line (IDL) – roughly follows the 180 medidian o East to West = add one day / West to East = lose one day Daylight savings time: starts the 2 Sunday in March and ends the 1 Sunday in November. o Exceptions: Arizona, Hawaii, PR, parts of Indiana, the Virgin Islands, and American Samoa 1/21/16 The Earth’s Revolution around the sun: Revolves on an orbit about equal to 365.242 days Elliptical Orbit o Perihelion – the distance between the earth and the sun on January 4 = 91.5 million miles o Aphelion – the distance between the earth and the sun on July 5 = 94.5 million miles o The average distance between the earth and the sun is 93 million miles which is equal to 1 astronomic unit (AU) There are four seasons because of the Earth’s axis tilt o Intensity of solar energy is related to the angle of incidence. The higher the angle, the greater the intensity. The Earth’s axis is tilted 66.5° from the plane of ecliptic o The plane of the equator and the plane of ecliptic have a difference of 23.5° Solstices Equinoxes: o Vernal – March 21 o Autumnal – September 23 Circle of Illumination – at any given time, ½ of the Earth is daytime, and half is nighttime. Important Parallels: Tropic of Cancer – 23.5° N – June Solstice sub solar point Tropic of Capricorn – 23.5° S – December solstice sub solar point Equator – 0° – equinox sub solar point Arctic Circle – 66.5° N – lowest latitude possible for 24 hours of daylight Antarctic Circle – 66.5° S Geographic Information Systems (GIS) – a computer system for capturing, storing, manipulating, analyzing, and displaying data related to positions on the earth’s surface 1/21/16 CHAPTER 2 Solar Energy: Radiation and electromagnetic spectrum o Wave length is measured in micrometers (um) 1m=1 million um Electromagnetic Spectrum – is divided into different wavelengths o Different objects produce different wavelengths o Gamma, xrays, ultra violet, infrared, microwave, radio Radiation – everything above 273°C (=absolute zero, 0° kelvin) emits radiation o The warmer the object, the shorter the wavelength (inverse relationship) Solar and Terrestrial Radiation: Sun: 6000°C (solar) o Three parts: Ultraviolet (0.30.4) Visible light (0.40.7) Shortwave Infrared (0.73) o Short waves (0.33um) Earth: Average surface temperature is 14°C (terrestrial) o Wave lengths emitted on Earth are longer than the sun o Thermal infrared waves (330um) – long waves Insolation: Insolation: incoming solar radiation Intercepted at the top of atmosphere layer Measured in units of watts per square meter Daily insolation: o Two factors: Sun rays’ angle – so the insolation is higher in the summer than in the winter The length of time of exposure to the rays Equator: o The two maximums happen on equinoxes because the sun is directly overhead (angle) o The two minimums happen on solstices Between 23.5°N/S o The two maximums: the closer the to 23.5°, the closer the two maximums 23.5° to 66.5° N/S: A single peak on the summer solstice 66.5° to 90° N/S o A single maximum on the summer solstice o Experiences no insolation during parts of the year o N/S poles – half a year have no insolation World Latitude Zones: Equatorial: 10°S 10°N Tropical: 10° 25° Subtropical: 25° 35° Midlatitude: 35° 55° Subarctic: 55° 60° Arctic: 60° 75° North Pole Area: 75° 90° Composition of the Atmosphere: Constant gasses: o Nitrogen 78% o Oxygen 21% o Argon almost 1% (inert) Variable Gasses: change over time and vary by regions o Carbon Dioxide 0.035% – used by green plants in photosynthesis – produced by respiration and burning of fossil fuels o Gaseous water (water vapor) 0.14% the most abundant greenhouse gas in the atmosphere, but it is not a concern because the total amount in the atmosphere remains relatively unchanged – it just varies by region o Others: methane, CFCs, dust and particles 1/26/16 Solar Energy: Solar energy transferring processes in the atmosphere Can either be absorbed (heating) or reflected (no heating) o The reflected percentage – albedo o Fresh snow = 8595% of incoming energy reflects back to the energy Only absorbs a small percentage o Dry sand = 3540% Explains why sand can get very hot in the bright sun o Tropical Forest =about 13% o Earth’s albedo =about 30% Sensible heat – heat that one can sense (warm air) Latent heat – heat used in the evaporation of water or liberated in condensation o When water is evaporated, the body of water lost water and heat to the atmosphere Latent heat transfer – transfers heat from an evaporating surface to the atmosphere Energy Balance: The earth as a whole, the incoming energy is balanced by outgoing energy The incoming energy and outgoing energy may not be balanced at a specific area or time Energy Surplus/Deficit o At lower latitudes – there is an energy surplus o At higher latitudes – there is an energy deficit Because of the sun ray angle The earth as a whole is balanced in energy by the transferring of energy from surplus areas to deficit areas. Poleward heat transfer moves surplus energy from low to high latitudes (atmosphere, ocean currents, water vapor) CHAPTER 3: Air Temperature 1. Temperature: A measure of heat Thermometers: liquid inside a glass tube Thermistor: electrical resistance Units of temperature: o Celsius (C) o Fahrenheit (F) o Kelvin (K) o Reference points: Freezing point = 0°C / 32°F / 273°K Boiling point = 100°C / 212°F / 373°K o Conversion: ON TEST Degrees Celsius = (degree Fahrenheit – 32)/1.8 Degree Celsius = degree Kelvin – 273 o Mean daily / monthly mean / annual mean / annual temperature range Factors affecting air temperature o Insolation – daily and seasonal variations o Latitude – also daily and seasonal variations and energy deficit o Surface type – albedo of surface as well as surface moisture o Coastal vs. interior location – temperature range is lower at coasts o Elevation – thinner atmosphere means less greenhouse effect 2. Daily Temperature Pattern: Recall daily insolation at midlatitude Net radiation – varies with the time of day and season o During the night, more energy is emitted from the surface o Early or late in the day there is a deficit because of the low sun angle 1/28/16 2. Daily Temperature Pattern: (continued) Rural areas – transpiration from leaves cools the surface o Evaporation from moist soils plus transpiration = evapotranspiration Urban areas – water is channeled so surfaces tend to be dry o More pavement – prevents evaporation o Building materials store heat, and the heat is released from buildings o Fuel consumption: urban areas > rural areas o The urban heat island Tends to persist over night More green areas (parks) reduce the heating Desert urban areas often do not exhibit heat islands, where irrigated vegetation may make the city cooler 3. Vertical Temperature Patterns: The earth’s atmosphere – made up of a series of concentric layers o Held down by gravity o Most of the atmosphere’s mass is near the surface o Structure: The troposphere is the lowest layer (nearest to the ground) The temperature decreases on average by 6.4°C/1000m in the troposphere (environmental lapse rate) So, you can estimate the temperature at the top of the mountain if you are at the bottom and know the height Stratosphere – ozone layer located here Mesosphere Thermosphere Elevation and Temperature: o Higher elevations: Lower average temperatures Greater difference between high and low temperatures – this is due to the decreased greenhouse o Temperature inversion – occasionally, the upper air is warmer than the lower air Occurs if the ground cools overnight Occurs typically on clear, cold winter nights Cold air may flow into an area – may have a bad impact on air quality – pollutants are trapped 4. Annual Temperature Patterns: Maritime and continental climates 5. World Patterns of Air Temperature Isotherms – what distribution of air temperature shown on a map uses – lines of equal temperature o Reveals centers of low or high temperatures and temperature gradients Large landmasses located in the subarctic and arctic zones develop centers of extremely low temperatures in the winter Temperatures in equatorial regions change little from January to July Areas of perpetual ice and snow are always intensely cold