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GG101 Midterm Review*.pdf

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Rich Petrone

Chapter 1 Parallels of Latitude - equator= largest - E-W Compass directions - across axis of rotation - Latitude = angular distance north or south of the equator, measured from the center of Earth Sub- dividing Latitude - 1degree of latitude = 110km of linear distance - more precision: minutes of arc (represented by ‘) - 1 minute of latitude= 1/60th of a degree - 1 minute of latitude ~ 1.83km of linear distance - MORE precision: seconds of arc (represented by “) - 1 second of arc is 1/60th of a minute - one second of arc is about 0.031km, which is very roughly 30m - Waterloo= lat. 43 degrees 28’ 04”N Meridians of Longitude Longitude: is the angular distance East or West of a point on Earths surface, measured from the center of the Earth - pole to pole axis rotation - only half way around the globe - N-S Compass directions Great Circles and Small Circles Great Circle: is any circle that splits the Earth into exactly half, or coincides with the center of the Earth (ex. Equator) Small Circle: is any circle that does not coincide with the center of the Earth (meridians) Map Projections Mercator projection: most commonly used, is a cylindrical projection Rhumb line: the line of constant direction or the mercator projection. Is a straight and thus facilitates plotting directions between two points 4 Classes of Map Projections: - Cylindrical - Planar - Conic - Oval Scales Written Scale: one mm equals 5km Representative Fraction: 1:250,000 or 1/ 250,000 Graphic Scale: Types of Scales: Small Scale: 1:2,500,000 Medium Scale: 1:125,000 Large Scale: 1:24,000 Earths Rotation - Planet spins slowly -> rotation= 1 solar day - Counter- clockwise direction when looking at the North Pole - Poles= intersections of axis of rotation and earth’s surface (N&S) Why is it Important? - convenience for humans - geographic grid - day - influences physical and life processes on Earth - Environmental Effects of Rotation - imposes daily or diurnal rhythms - flow paths of air/water are turned in one direction - movement of tides Global Time Zones- Relationships with Longitude - 15 degrees of longitude= 1hr of time - International Date Line: - which marks the place where each day officially begins at 12am - the day is swept wester ward across the globe, starting at The International Date Line World Time Zones - Standard Time - divides the globe into 24 time zones - Daylight Savings Time - done to maximize daylight period - International Date Line - Same calendar day at midnight; any other time= different days Chapter 2 How Do Earth- Sun Relations Affect Seasonality on Earth - Seasonality: seasonal variation of: - 1. Sun’s Position above the horizon - a) Altitude - b) Declination - 2. Changing day lengths Perihelion: closest to the sun, January 3, 147,255,000km Aphelion: Farthest from the sun, July 4, 152,083,000km Reasons for the Seasons 1. Revolution 2. Rotation 3. Tilt of Earth’s axis 4. Axial Parallelism 5. Sphericity Factor Description Revolution Orbit around the Sun; requires 365.24 days to complete at 107,280km Rotation Earth turning on its axis; takes approximately 24 hours to complete Tilt Axis is aligned at about 23.5 degree angle from a perpendicular to the plane of the ecliptic (the plane of earths orbit Axial Parallelism Remains in a fixed alignment, with Polaris directly overhead at the North Pole throughout the year Sphericity Appears as an oblate spheroid to the Sun’s parallel rays; the geoid Tilt Of Earths Axis - The earth's axis is tilted not quite 23½° from “the vertical”. “The vertical”? ▯ - The plane of reference from which earth is tilted = "plane of ecliptic.” (yellow) - - - This is the plane of the earth's orbit around the sun. - Earth is at a 23 ½ degree angle at it moves around the sun –part of the planet points toward the sun at one point and at the same time, part of the planet is pointing away from the sun – consider the alternatives… - if the earth were tilted on its side with its axis parallel to the plane of the ecliptic we would see huge variation in seasons worldwide (think about it, half of the earth would be dark for 6 months). - if the earth’s axis was perpendicular to the plane of the ecliptic (ie no tilt at all), we would experience perpetual fall/spring like season, and, all points on planet would get 12 hrs of sunlight 4 Seasons - March of the Seasons (earth’s relationship with sun during yr) - SHOW circle of illumination - SHOW Axial parallelism - SUBOLAR PT – point on earth where sun is directly overhead – this is also going to change during the year – you will see this better in the next slide - 4 imp dates (2 solstice, 2 equinox) – - SOLSTICE: occur winter/summer. Winter: N tilted away=no sun; Summer N tilted towards sun. (while earth rotates on axis) - > Result: long daylength at N pole summer and no sun at S pole in summer (reverse in winter) - EQUINOX neither pole is pointed away from sun. - Result: exactly 12 hrs day/night - >Changing daylength not big deal at our latitude, but has huge effects at poles (eg Churchill = 18.5hrs day); higher arctic = light for 24 hours (or dark) Solstice Solstice: summer: subsolar pt on T of Cancer (N pole = 24 hrs of day); winter, subsolar pt on T of Capricorn (N pole = 24 hrs of darkness) - See subsolar pt - in summer, sun’s rays are more direct than in winter, thus more energy at surface, and thus warmer temperatures) -> so here in the N hemisphere, not only is daylength longer, but also, the sun’s rays are more intense in summer. Equinox: circ of illum passes thru N and S poles and subsolar pt is on equator (90 degree angle b/w sun’s rays and earth’s surface; = 12 hrs day, 12 hrs night anywhere on globe) EXCEPT AT POLES where sun is on horizon for 24 hrs -sun lower in the sky in Dec in the midlatitudes of N America compared to June where it is high overhead.(ie altitude of sun in sky) TRACE THE PATH OF THE SUN ACROSS THE SKY. - This change in the sun’s altitude affects the amt of sunlight hitting a specific location on the planet. We’ll talk more of this next day. You can also see differences in daylength in this diagram… Also note the changing position of sunset and sunrise along the horizon during the year.. - So, from everything we’ve talked about today in terms of the earth-sun relations – things like revolution and rotation, and axial characteristics, you can really get a feel for how these things drive seasonality in terms of the exposure of the earth’s surface to sunlight… next lecture we’ll look at solar radiation in more detail. Chapter 3 Composition of the Atmosphere - Atmosphere= air - =mix of various gases - air held to earth by gravitational attraction - air=78%N, 21%O, and 1% other gases (including Argon, Co2, H20 vpr, and O3) (in homosphere - Temperature decreases with increased altitude at a rate known as the normal lapse rate. Scientists use the standard atmosphere as a description of air temperature and pressure changes with altitude. Atmospheric CO2 Concentrations - since 1992, the global concentration of CO2 in our atmosphere has increased more that 16%, from 354ppm to 394ppm in 2011. For comparison, preindustrial levels of CO2 were about 280ppm. CO2 today exceeds the natural range of 180 to 300ppm over the last 800,000 years. The CO2 Molecule - linear molecule- central (C) atom and 2 flanking (O) atmoms - O= more attractive to e-’s - BUT this molecule is symmetrical: partial dipole moment of the 2 C-O bonds cancel each other out - BUT molecules vibrate in different ways, bonds stretch or bend Atmospheric Function Criterium for Layers: Ionosphere: Altitude of thermosphere and mesosphere Ozonosphere: within stratosphere ############################# UV Exposure Hazards - due to the over exposure of insoltation, UV radiation has come up with an index telling people how harmful the sun is, and how it is getting worse. Chapter 4 Radiation and Energy Balances Electromagnetic Radiation (EMR) - EMR encompasses a spectrum of waves of energy-> different wavelengths What is a Wavelength? - distance between wave crests Radiation And Temperature- 2 important Principles - hotter objects radiate more energy and at shorter wavelengths than cooler objects Insolation - Solar Constant (arriving at earth’s atmos): 1400 W/m2 - = flow of energy intercepted by Earth’s surface - varies from place to place and time to time - depends on angle of sun above horizon Daily Insolation throughout the Year - Controlled by: - angle of sun’s rays on earth - length of exposure to rays - seasonal pattern of daily insolation is linked directly to latitude - Shortwave Radiation from the Sun-> denoted as “K” - Longwave Radiation from the Earth-> denoted as “L” Transmission: refers to the passage of shortwave energy through either the atmosphere or water Scattering: changing the direction of the radiations movement without the alternating its wavelength Albedo - ability of a surface to reflect K incoming - expressed as a ratio (Koutgoing/ Kincoming) - mainly affected by colour of surface - black body Longwave from Earth (L outgoing) - Counter radiation and the Greenhouse effect - clouds absorb L outgoing and reradiate it to earth= counter radiation - the lower atmosphere acts like a blanket that returns heat to earth-> reduces temper
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