Lecture 1 The Earth As A Rotating Planet Geog210 Physical Geography What is Geography? Much more than place names and locations The study of spatial variation How and why things differ from place to place on the surface of the earth How observable spatial patterns evolved through time Focus on the interaction of people and social groups with their environment and with each other Geography is about space and the content of space Michael Paluzzi, ABD What is Geography? What is geography? Geography -"writing about the earth and is defined as the study of the earth and its features and of the distribution of life on the earth, including human life and the effects of human activity Geographers try to answer three questions: Where? Why there? Why do we care? Why are these questions important? Subfields of Geography? Regional geography Identify particular segments of the earth s surface for study Systematic geography Identify particular classes of things for study Human geography Focus is on people Physical geography Focus is on the natural environment Some Core Geographic Concepts Spatial is an essential modifier in forming questions and framing concepts Geography is a spatial science The geographer s space is earth space The way things are distributed The way movements occur Some Core Geographic Concepts Basic observations regarding places: They have location, direction, and distance with respect to other places They have size They have both physical structure and cultural content Their attributes develop and change over time Their elements interrelate with other places They may be generalized into regions of similarities and differences 1
Absolute location Based on a precise and accepted system of coordinates-- mathematical location Latitude and longitude Other grid systems UTM, SPC SUNY Rockland 41.13208 N -74.08404 W Location Location Relative location is the position of one place with respect to another place or set of places. (e.g. Central Valley is north of Suffern, NY) In relation to Suffern, we know Central Valley is north, but how far? They are relatively if you have a car, but what if you are walking? Are they still close? Direction Absolute direction Based on the cardinal points (N- S-E-W) Relative direction Culturally based and locationally variable Out West Back East Down South Near East Far East Distance Absolute distance Uses standard units such as miles or kilometers Relative distance Transforms linear measurements into other units more meaningful for the space relationship in question Two places might be the same distance, but differ in relative distance Time Money - psychological Physical and Cultural Attributes Physical attributes of a place Climate, soil, water supplies, mineral resources, terrain features, etc. Natural landscape Helps shape but does not dictate how people live Physical dictates the resources available, culture determines how those resources are utilized. Cultural attributes of a place Language, religion, industries, food, music, etc. Cultural landscape Visible imprint of human activity Physical and Cultural Attributes Differences in the cultural landscape California Mexico Border High agricultural output in CA Lower agricultural output in Mexico 2
Attributes of Place are Always Changing The physical environment undergoes continuous and pronounced change Islands form and disappear Mountains rise and erode Glaciers move and melt Sea levels rise and fall in response to glaciers Humans alter the environments they occupy Pace of change has accelerated Built landscape has increasingly replaced natural landscape Places are the present result of past operation of distinctive physical and cultural processes Place Similarity and Regions No two places on earth can be exactly the same The natural and cultural characteristics of places show patterns of similarity in some areas Regions A region - common characteristics or phenomena that are commonly found throughout its territory. This common characteristic is not generally found in surrounding territory or it would be part of the region Used to classify the complex reality of the earth s surface into manageable pieces Types of Regions Formal (uniform) regions Uniformity in one or a limited combination of physical or cultural features Formal region (most aware of) - one or more criteria that are used to mark off unique or different areas of the earth s surface Climate regions, crop types, soil types Types of Regions Functional (nodal) regions has a definite center or node - spatial interaction occurs between this center(s) and all other parts of the region. The Midwest Which states belong to the Midwest region of the United States? Regions Vernacular region - is a region that is in the minds of people, and thus can vary according to an individual's perception. sometimes known as a perceptual region. As we just saw, the Midwest because different people have a different idea of what areas are included in the region. Reflect feelings and images rather than objective data 3
The Shape of the Earth The Earth is round.roughly.. How do we know? A Spherical Planet oblate ellipsoid slightly flattened The geoid exaggerates small departures from spherical Geodesy the science that measures the earth s shape Highly mathematical The Earth s Rotation Earth rotates on its axis: Counterclockwise at North Pole Left to right (eastward) at Equator One rotation is a solar day (24 hours) Maps Basic models and means of communication used by geographers to depict the earth s surface. Map a representation, normally to scale and on a flat medium, of a selection of material or abstract features on, or in relation to, the surface of the earth. Map not drawn to scale? Axis: an imaginary straight line through the center of the Earth around which the Earth rotates Parallels and Meridians Geographic grid: network of parallels and meridians used to fix location on the Earth Parallel: east-west circle on the Earth s surface, lying on a plane parallel to the equator Meridian: north-south line on the Earth s surface, connecting the poles Latitude is the angular distance from the equator. Equator: Parallel of latitude lying midway between the Earth s poles; it is designated latitude 0º Longest parallel of latitude Midway between poles Fundamental reference line for measuring position 4
Longitude: arc of a parallel between the prime meridian and a given point on the globe Longitude is the angular distance from the prime meridian - Royal Observatory in Greenwich, England (0 ). Latitude & Longitude Latitude is from 0º (Equator) to 90º (Poles) North (N) & South (S) Longitude is 0º (Prime Meridian) to 180º East (E) & West (W) Unlike latitude, longitude lines are only equidistant along the equator. As you move poleward lines of longitude converge. Latitude & Longitude of a Point Latitude & Longitude together pinpoint locations on the geographic grid. Fractions of degree angles are described using minutes & seconds Minutes = 1/60 th of a degree Seconds = 1/3600 th of a degree Ex. 41 27 41 N 41 degrees Plus 27/60ths of a degree Plus 41/3600ths of a degree 41 27 41 N = 41.4614 Map Scale Two Main Map Controls Scale & Projection Scale ratio of map units to ground units Controls: how features are shown what features are shown. Scale also controls the level of detail and hence the purpose of the map. verbal representative fraction (or ratio) Scale can be graphical Scale Can range from very large to very small Large-scale maps A large scale map covers a small area and shows great detail. Ratio of map to ground distance is relatively large RF is large, e.g. 1/10,000 Small-scale maps A small scale map covers a large area and shows only large or prominent features. Ratio of map to ground distance is smaller RF is small, e.g. 1/100,000,000. 5
Effects of Scale Scale controls not only how features are shown, but what features are shown. Scale also controls the level of detail and hence the purpose of the map. Effect of Scale Channel contours give depth below water level, more detail is represented. Waterline is shown to depict location of channel lacking details Channel no longer a polygon represented as a solid line minimal detail. Map Controls A map projection is the mathematical transformation of space from the surface of the earth to that of a flat plane. Curved surface cannot be projected onto a flat sheet without distortion Distortion - least for small areas and greatest when a map attempts to show the entire surface of the Earth. are identified by the distortions which they avoid The four main properties of maps: 1. Shape 2. Distance 3. Relative size (area) 4. Direction The projection we choose will limit the distortion to the properties you are trying to maintain. Greenland vs. South America Which one is bigger? 6
Conformal projections Mercator projection: Used for navigation Scale increases from equator to poles Straight line on the map is a line of constant compass bearing Equal-area (equivalent) projections Areas are in correct proportion to earth reality Shape is distorted Goode Projection: Equal-area map projection Shows true sizes of regions on Earth s surface Distorts shapes of places, especially high latitudes and at edges of map Equidistant projections Distances are true in all directions from one or two central points A map cannot be both equidistant and equal-area Azimuthal projections Directions are true from one central point to all others Robinson projection Compromise between equal-area and conformal Fairly realistic view of the world Distortion is greatest in less populated places (N. Canada Greenland Russia) US 3% smaller Canada 21% larger 7
Great Circles Which line is shorter? Great Circles Great Circle A circle on the surface of a sphere that has the same circumference as the sphere Must go through the center of the sphere A great circle divides the sphere in two equal hemispheres meridians are great circles, and the equator An infinite number exist Shortest distance between two points As a result, they are often used by airline Small Circles A small circle of a sphere is the circle constructed by a plane crossing the sphere Does not cross the center Small circles always have smaller diameters than the sphere itself Standard Time: time system based on the local time of a standard meridian and applied to belts of longitude extending roughly 7 ½ º on either side of the meridian World Time Zones World Times Zones International Date Line 180 th meridian Moving west across the date line: advance calendar one day Moving east across date line: set calendar back one day No change in clock time when crossing date line The world s 24 standard time zones each represent about 15 of longitude. 8
Remote Sensing Obtaining images of an area from a distance Aerial photography Standard photographic film Infrared film False-color images Nonphotographic imagery Thermal scanners Radar Lidar (light detection and radar Satellites Landsat satellites The Global Positioning System (GPS) GPS is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. Geographic Information Systems (GIS) Computer-based set of procedures for gathering, storing, manipulating, analyzing, and displaying geographically referenced data Geographic database Digital record of geographic information Maps, surveys, aerial photos, satellite images, etc. Purpose of study determines data Applications of GIS Various fields for a variety of purposes, including: Biologists and ecologists: studying environmental problems Epidemiologists: studying diffusion of diseases and entomological risk factors Political scientists: evaluating legislative districts Sociologists: examining patterns of segregation Private sector companies: site selection, analyzing sales territories, calculating optimal driving routes Government: transportation planning, analyzing patterns of crime, responding to disasters 9