the geographers tool kit Flashcards
relative location
referencing one place in comparison to another
for example Saskatoon is located north of Regina
absolute location
precise system of locating a place in space using latitude and longitude
for example, Saskatoon is located precisely at a latitude of 52.1579°N and a longitude of -106.6702°W
the geographic grid
consists of a set of intersecting circles; one set extends north and south and one set extends east and west
great circles bisect earth into 2 equal halves (prime meridian, north and south) and (equator, east and west)
represents the shortest distance between any 2 points on earths surface
smaller circles have smaller diameters (east west)
meridians of longitude
all great circles
parallels of latitude
equator is a great circle, all others are small circles
________ is an angular distance north or south of the equator measured from the centre of the earth, example 49°N, 12°S
latitude
Latitudinal geographic zones chart
____________ is an angular distance east or west of a point on earths surface measured from the centre of earth
longitude
a line connecting all points along the same longitude is a ____________ The prime _________ is a ___________ designated as 0°
meridian
a line connecting all points along the same latitudinal angle is a
parallel
in 1884 at the international meridian conference held in washington DC 22 countries voted to adopt the _____________ ____________ as the prime meridian of the world
Greenwich meridian
the international date line is located approximatley along the ______ meridian (180E=180W)
180th
Co-ordinate system chart
parallels of latitude and meridians of longitude allow all places on earth to be located precisely
example, Moncton is located at 46°N, -65°W
______ the basic tool of geographers
maps
maps represent
tools for geographic information storage and portrayal
map making is termed
cartography
cartography has become __________
geomatics - integration of map making and data analysis with computers
cartography focuses on ways to display __________________ so that it can be used and understood efficiently
spatial information
a _________ is the most visually complete and accurate way to represent the earth
globe
present spatial/temporal information about earths systems and inhabitants
position, size, shape, boundaries
motion, dispersal,
spatial, temporal variations
information associated with specific locations
spatial data are obtained by observation or sampling
direct observation “ground truth”
remote sensing
methods of map storage
hard copy: notebooks, air photos, digital or optical images
data sotred on various electronical media
spatial data can be displayed on maps in many forms
place names, written discriptions
symbols: points, lines, polygons
tables of numeric data
spatial data displayed on maps
point data
line data
polygon data
a reference map shows the location of features and places and is designed for
general use
a thematic map shows one or a limited number of types of information or themes
dot maps
chlorpleth maps
isoline maps
dot maps
suitable for displaying non-continuous or discrete data that vary from one place to another
choropleth
represent data by using different colours or intensity of shading, used for that are sorted into classes
isoline maps
isolines are lines connecting points of equal value on a map, there is various kinds
isobars: atmospheric pressure
isopachs: sediment thickness
isotherms: temperature
isohyets: precipitation
contours lines: elevation
topographic maps
the closer the spacing of the contour lines, the steeper the slope
contour lines that form closed circles represent hills. closed circles with hatch marks indicate depressions
where contour lines cross streams, they form V’s pointing upstream
contour lines never touch or cross because each contour line represents a specific value at every point on that line
_________ is a critical part of cartography
map scale
it relates to the size of features on a map to their actual size in the real world
relates the distance between features on a map to the distance on earth
three map scales:
representitive fraction, written scale, and graphic scale
there is one advantage associated with the graphic scale, because if a map is enlarged or reduced, the graphic scale enlarges or reduces along with the map.
3D maps
globes
a globe is a real map that portrays spatial data on a 3D surface
requires a framework for placement of information on a map, the geographic grid,
true shape and area of objects are preserved
map projections
transfer of spatial data from three to two dimensions (to create flat maps of a three dimensional reality) results in the distortion of the shape and or area of objects, or distances between objects displayed on a map
types of map projections
light-source-type
cartographically derived
conformal map projections
Conformal(true angle)
maintains angles but area of objects is distorted, example Mercator projection
straight line drawn on map represents a line of constant compass bearing: useful for navigation
map scale varies: distortion increases towards the poles
Equivalent (equal area) maintains true area/size of objects is distorted
more accurate portrayal of the geographic grid
example eckert equal area projection
planar
meridians are straight lines radiating from a central point
parallels are complete circles
useful for focusing on single regions
often used for accurate views of the poles
conic
best suited for land masses with east-west orientations or small countries
interrupted map projections
mathematically created map is interrupted over ocean basins to minimize distortion of land masses - an equivalent projections
digital technology in geography
remote sensing
new approacj to spatial analysis: involves measuring properties of the enviroment without direct contact
started with aerial photography
-systematic photographs taken in succesion over linear flight lines at set intervals of time
-limiting because complete sets of photgraphs of large regions were only taken at irregular intervals of time
Later technology - satelite imagery
-sun-synchronous orbit, keeps pace with suns westward progress
-geostationary orbit remains permanently in one place above earth
sun-synchronous satellite platforms
- landsat operated jointly by NASA, NOAA, USGS
- employed in mapping coastlines, forests, and forest fires, vegetation identification, ground temperatures, and soil moisture
Advanced very high resolution radiometer (AVHHR)
- measures cloud cover ad ground surface temperatures
geostaionary satelite platforms
geostationary
operational
enviromental
satellites
(GOES)
monitor weather phenomena
- cloud cover, tornadoes, hurricanes, hail, storms, flash flooding`
passive remote sensing
- instruments detect energy emitted from the surface of earth example camera and aerial photography
active remote sensing
- instuments emit their own radiation and then detect, and analyze, what is reflected back example: radar-radio detection and ranging, lidar - light detection and ranging
Geographic information systems (GIS)
system for storing, analyizing, and manipulating spatially referenced data
(GIS) databases consost of series of individual data layers
a data layer contains measurements for a specific geographic variable, such as vegetation, soils hydrology, road networks, municipal infastructure, etc
GIS map data
Map data(where) and attribute data(what) are displayed as either
vector data - use latitude and longitude to represent feathers as points, lines, and polygons
raster data use equal size cells to represent features
each layer in GIS is assigned a variety of
detailed attributes
each layer exists as a
distinct unit
for analysis or display, layers are
overlaid or combined
elements of GIS
data aquisition
data processing
data management
data manipulation
generate maps (virtual or real)
key of GIS is common locational identifiers for all the information (georefrencing); commonly acquired with a global positioning system device
Global positioning systems GPS
system of sattelites and receivers
24 satelites orbit earth every 12 hours
a radio signal, pseudorandom code PSR transmits in sequence of pulses
signal is received by GPS receiver
determine location in geographic grid through a system trileration (triangulation)
trilateration/triangulation
signals from up to four satellites overlap to pinpoint
what are two components of the geographic grid and how are they calculated?
latitude and longitude, calculated from a central point
define the boundaries of latittudinal geographic zones
indentify three type of thematic maps
discuss the concept of map projection and why it is necessary when constructing maps
which would the larger scale: a map showing the detail of vancouver or a map showing the position of vancouver within the province of british columbia?
the map of vancouver would be zoomed in and 1 unit would be equal to less area or distance for example 1:20
whereas the map of bc and vancouvers location would be 1 unit equal more distance for example 1:250
define the concept of remote sensing
the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance
what is the differnce between active and passive remote sensing
Active remote sensing instruments operate with their own source of emission or light, while passive ones rely on the reflected one.
describe the character of a geographical information system
a computer system capable of capturing, storing, analyzing, and displaying geographically referenced information;
