ESSENTIALS of GEOGRAPHY Physical Geography (Geog. 300) Prof. Hugh Howard American River College
GEOGRAPHY
GEOGRAPHY Earth description, or study of Earth Describes the natural environment and human interaction with it Spatial science, having to do with physical space Deals with spatial distributions and spatial relationships of Earth features and phenomena
GEOGRAPHY Ancient Greeks didn t invent geography, but they formalized it as a field of study Organized all knowledge into Geography and Cosmography Eratosthenes coined the term geography in the 3 rd century BCE He was the first person to calculate the circumference of Earth (using geometry) Geographic library at Alexandria
GEOGRAPHY Geography has two major subfields Physical Weather, climate, geology, hydrology, soils, etc. The emphasis of this course Human Cultural, economic, political
Major Subfields of Geography
GEOGRAPHY Synthesizes other fields of study Geology, hydrology, meteorology, etc. Geography acts to bring specialized fields together to find relationships between them
THE SCIENTIFIC METHOD
SCIENTIFIC METHOD Method for investigating phenomena and acquiring new knowledge A hypothesis is formed A proposed explanation for something Is formed by making a general statement from specific observations Mt. Shasta is a volcano. It is made of lava. Therefore, all volcanoes are made of lava.
SCIENTIFIC METHOD Hypotheses are based on inductive reasoning Generalizing from specific observations Allows for the conclusion to be false Mt. Shasta is a volcano. It is very large. Therefore, all volcanoes are very large. Hypotheses can be supported or rejected on a case-by-case basis
SCIENTIFIC METHOD Hypotheses are tested using deductive reasoning Reasoning from a general statement to a logical conclusion Mt. Shasta is a volcano. It is formed from lava. Therefore, all volcanoes are formed from lava. The hypothesis is accepted Experiments performed on all known volcanoes show that they are all made of lava.
SCIENTIFIC METHOD Hypotheses are tested using deductive reasoning Reasoning from a general statement to a logical conclusion Mt. Shasta is a volcano. It is very large. Therefore, all volcanoes are very large. The hypothesis is rejected Experiments performed on all known volcanoes show that they vary in size.
The Scientific Method A Theory Is a well-substantiated explanation acquired through the scientific method, and repeatedly confirmed through observation and experimentation. There is a very high probability that it is true.
SYSTEMS and MODELS
SYSTEM Set of related objects or events Useful in identifying relationships and interactions between components Used by geographers to organize information Open System Allows exchange of energy and matter (a tree)
Open System
Earth SYSTEM Is an open system all components interact
Earth SYSTEM Is a closed system in the context of space Allows exchange of energy only (really?)
MODEL Simplified, idealized representation of reality Maps and globes as models Physical or computer Allow us to see the most prominent, or important aspects of a system
Models of Earth
EARTH as a SYSTEM: The FOUR SPHERES
Atmosphere The FOUR SPHERES Extends up 300 miles Uneven solar heating keep it in constant motion, causing weather Lithosphere The rock layer Earth s outer shell, including the continents and ocean floors
The FOUR SPHERES Hydrosphere All water on and in the lithosphere Oceans constitute the largest component: 71% of Earth s surface Biosphere Life Layer - all living things We ll focus less on the biosphere than on the first three spheres
REGIONAL SUB-SYSTEMS: All four spheres can be studied within a particular geographic region Earth s Four Spheres
The SPHERICAL EARTH
SHAPE of EARTH Ancient Greeks believed that Earth was a sphere Ships disappeared over the horizon Lunar eclipses provided clues They believed the sphere to be a perfect form, appropriate for Earth Earth is not a perfect sphere It is spherical
The Spherical Earth
Half of a sphere HEMISPHERES Earth can be divided in many ways Northern and Southern Defined by the equator 70% of land is in the northern 90% of the human population is in the northern
HEMISPHERES Eastern and Western Defined by humans, rather than by physical principles International Meridian Conference, 1884, Washington, D.C. The Prime Meridian (0 degrees longitude) passes through Greenwich, England
The Four Hemispheres
Land and Water HEMISPHERES Land hemisphere centered on Africa Water centered on the Pacific The Water Hemisphere
CONTINENTS and OCEANS
CONTINENTS Continents Large, continuous, discrete masses of land Six continents Africa, Antarctica, Australia, N. America, S. America, Eurasia Europe is not a continent, but part of Eurasia It can be considered a sub-continent, or cultural region
Oceans OCEANS Large bodies of saline water Five oceans Arctic, Atlantic, Indian, Pacific, Southern Further subdivisions are made N. Atlantic and S. Atlantic, etc. Really only one global ocean
Continents and Oceans
AFRICA The mother continent for humans Second largest ( 20% of land area) Center of land hemisphere Straddles equator Plateau continent Much is over 3,000 ft, but large mountain ranges are uncommon
Africa
ANTARCTICA Home to the South Pole Second smallest ( 9% of land area) Surrounded by the Southern Ocean World s largest ice sheet Population 1,000-4,000 Scientists and support workers
Antarctica
AUSTRALIA Smallest ( 6% of land area) Great Dividing Range Lowest and flattest continent Highest point is only 7,316 ft Interior is almost completely uninhabited
Australia
Australia 2% of total population lives in yellow area
NORTH AMERICA Home! 17% of land area Great Mountain Ranges Rocky Mountains, Sierra Nevada, Cascade, Appalachians Great Plains Mississippi/Missouri Rivers and basins
North America
SOUTH AMERICA Last continent to be settled by humans 12% of land area Andes Earth s longest mountain range Amazon Earth s longest river Angel Falls Earth s highest waterfall
South America
EURASIA Largest ( 36% of land area) Himalaya Earth s tallest mountain range Almost 5.5 miles high, >29,000ft Alps Europe s greatest mountain range Densely populated river plains Ganges, Yellow, Yangzi
Eurasia
THE GEOGRAPHIC GRID
The GEOGRAPHIC GRID System for locating places on Earth Meridians Lines that stretch from north to south pole Prime Meridian passes through Greenwich Parallels Circles that intersect meridians at right angles, but are parallel to themselves Equator is a parallel
Meridians
Parallels
DEGREES Ancient Babylonians divided the circle into 360 equal parts Degrees! This system was applied to meridians and parallels Allows us to describe any location on Earth
DEGREES Degrees are too coarse to allow precise descriptions of location, so refinements were made Degrees, Minutes, and Seconds Angles, not units of time 60 (minutes) in 1 (degree) 60 (seconds) in 1 (minute) 3,600 (seconds) in 1 (degree)
LONGITUDE A measurement, in degrees, E or W of the Prime Meridian (Greenwich) 0-180 East or West One degree of longitude is 69 mi (111 km) at the equator and 0 mi at the poles. Sacramento: 121 28 W
Longitude
LATITUDE A measurement, in degrees, north or south of the equator (a parallel) 0-90 North or South One degree of latitude is 69 mi (111 km) anywhere on Earth Latitude: ladder, or lattice Sacramento: 38 33 N
Latitude
Latitudinal Zones
GLOBAL TIME
TIME and the GRID Earth completes one rotation every day, or every 24 hours Because Earth is composed of 360 degrees of longitude One hour of time corresponds with 15 degrees of longitude (360 /24 hours = 15 /hour)
TIME and the GRID Standard Meridians divide Earth into one hour zones The sun moves 15 in the sky every hour
SOLAR NOON Time when the sun reaches its highest point above a particular place on Earth Actual noon (differs from clock noon) Different for every longitude Earlier for Sacramento than for San Francisco But our clocks tell us that noon is at the same time in both places
TIME ZONES Regions 15 wide that share a common Standard Time Solar noon of the center of each zone is used throughout the zone Simplifies time scheduling Zones are actually irregular due to political and natural boundaries
Time Zones International Date Line: If traveling westward, you advance to the next day. If traveling eastward, you repeat the same day.
DAYLIGHT SAVING TIME The advancement of local times by one hour in spring and summer Gains more daylight in the evenings Designed to reduce energy consumption after dark (artificial lighting used to be a primary energy drain) Second Sunday in March First Sunday in November (8 months)
Daylight Saving Time
MAPS and MAP PROJECTIONS
MAPS Reduced, simplified version of geographic reality Allow us to communicate geographic information Predate written language Maps represent the spherical Earth on a flat surface, or plane
Maps
MAP PROJECTION The arrangement of Earth s spherical surface on a plane Projections can be classified according to geometric properties Planar Cylindrical Conic
Planar Map Projection
Cylindrical Map Projection
Conic Map Projection
MAP PROJECTION The projection process always distorts the continents and oceans Orange peel example The map maker can choose a specific type of projection that will be appropriate for a particular map Equal Area Conformal
MAP PROJECTION Equal Area Projection Retains the property of area Areas are shown at their correct sizes in relation to other areas (shape is distorted) Conformal Projection Retains the property of shape Shapes of areas and lines are correct (area is distorted)
Equal Area Map Projection (Eckert IV)
Equal Area Map Projection (Sinusoidal)
Conformal Map Projection (Mercator)
Conformal Map Projection (Lambert)
MAP SCALE
MAP SCALE A ratio (fraction) of map distance over Earth distance The representative fraction M a p d i s t a n c e E a r t h d i s t a n c e 1 24, 000 o r 1 : 2 4, 0 0 0 Unitless: any unit of measure can be inserted
MAP SCALE THE REPRESENTATIVE FRACTION (R.F.) 1:5,000,000 1:5,000,000 (larger scale) 1:20,000,000 1:20,000,000 (smaller scale) O R E G O N Smaller Area Greater Detail Greater Detail Larger Area Lesser Detail Larger Area Lesser Detail
GEOGRAPHIC TECHNOLOGIES
GEOGRAPHIC TECHNOLOGIES Technologies that allow us to examine and analyze geography Global Positioning System (GPS) Remote Sensing Geographic Information Systems (GIS) Computer-based fields that offer career paths
Global Positioning System (GPS)
Remote Sensing
Geographic Information Systems (GIS)
Geographic Information Systems (GIS)
Geographic Information Systems (GIS)
Geographic Information Systems (GIS)
Geographic Information Systems (GIS)
ESSENTIALS of GEOGRAPHY Physical Geography (Geog. 300) Prof. Hugh Howard American River College