Aubert – GEOG 300
Remote Sensing (RS)
Remote sensing is the collection of images and data from a distance, usually
from instruments flying above the Earth (for example, in airplanes, satellites,
and/or the International Space Station). Remote sensing instruments most
commonly detect reflected sunlight (like a photograph!), emitted longwave
(like night vision infrared goggles!), or backscatter (like radar!).
• A passive sensor reads only naturally occurring energy (such as
reflected sunlight and emitted longwave).
• An active sensor reads only backscatter, which is the term for the
energy reflected back at the sensor after it blasts pulses of energy
(like radio waves) at Earth.
Global Positioning System (GPS)
The Global Positioning System includes two main components. The first is a
network of 24 space based satellites which sends out timed signals. The
second is ground-based receivers which read these signals and calculate and
record exact location data. If a GPS ground receiver is moving (for example, in
a car), speed and direction can also be calculated.
• Data collected and stored by a GPS receiver can be fed into a
Geographic Information System (GIS) to create digital maps. See
more below.
• The GPS receiver alone cannot navigate or give directions. It can,
though, feed your real-time location into a GIS (interactive digital
map) which can then navigate and give directions. See below.
Geographic Information System (GIS)
A Geographic Information System (GIS) is a computer program which can
create interactive, digital maps which are able to display and analyze spatial
(mapped) data. The data in a GIS can come from scanning (digitizing) paper
maps, but more commonly it now comes directly from GPS and remote
sensing instruments. This is exactly the type of technology which has been
used to build Google Earth, Google Maps, and other online mapping
applications.
Remember, a GPS receiver alone cannot navigate or give directions. It can,
though, feed your real-time location into a GIS (interactive digital map) which
can then calculate, navigate and give directions. In other words, modern
navigation devices must combine both GIS and GPS!
A Simplified Introduction to Common
GEOSPATIAL TECHNOLOGIES
Remote Sensing data is used
to
create maps in a GIS…
GPS data is also used to
create maps in a GIS…
PAGE
>
John Aubert ( American River College
Location, Time, Maps, and Technology
Physical Geography Lecture Notes
Page
1
of
3
aubertj@arc.losrios.edu
Location and Time
I.
Location – The Geographic Grid: In order to better measure and navigate around Earth and evaluate global environmental phenomena, humans have imposed a grid system over the entire globe. These are the parallels of latitude and the meridians of longitude.
A.
Parallels of Latitude (measures degrees north and south of the Equator): Imaginary Circles (reference points) drawn on the globe perpendicular to the axis (side to side) to measure angular distance in degrees North or South of the Equator.
Lat = Flat
1.
Angular Distance: Angular distance is a distance measured in degrees as opposed to miles or kilometers. Latitude is measured in degrees north or south of the Equator. Each degree of latitude is approximately 110 km (
7
0 miles),
2.
Equator: The line of latitude which perfectly bisects the globe between the north and south poles is called the Equator; it is designated as 0°Latitude.
B.
Meridians of Longitude (measures degrees east and west of the Prime Meridian): Imaginary Circles drawn on the globe between the North and South Poles. They are used to measure angular distance in degrees East or West from the Prime Meridian. They cross all parallels of latitude at right angles.
1.
Angular Distance: Longitude is measured in degrees east or west of the Prime Meridian. At the Equator one degree of longitude is approximately 110 km (70 miles); this steadily decreases approaching the poles.
2.
Prime Meridian: This is the meridian designated as 0°Longitude. Decided arbitrarily. Passes through the old Royal Observatory at Greenwich, England.
C.
Combining Latitude and Longitude: A correct location on the geographic grid must give Latitude (North OR South) AND Longitude (East or West). Sacramento, California is located at approx. 3
9
° North Latitude and 121° West Longitude
II.
Time
A.
Earth’s Rotation:
· Earth rotates on its axis, which is an imaginary line passing through Earth from the north pole to the south pole.
· One rotation takes approx. 2
4
hours (rotates 1
5
degrees per hour)
· The direction of rotation is toward the east.
B.
Solar Noon: Solar noon refers to the moment when the sun is at its highest point in the sky, generally occurring around clock Noon. Solar noon “travels” or “migrates” from east to west across the globe (as does sunrise and sunset).
C.
Time Zones (see map in text):
· A time zone is an area where everyone agrees to observe the same time, regardless of the position of the Sun.
· There are 24 primary time zones, each being 15( of longitude wide. Many countries modify this system; it is ultimately political.
· Each time zone has a controlling meridian (the exact longitude where solar noon and clock noon are the same).
D.
International Date Line:
· Located at approx. 1
8
0( Longitude in the Pacific; exists to prevent the “impression” of time travel.
· Travel eastward across it (toward the Americas) and go backward one calendar day (regardless of the time of day).
· Travel westward across it (toward Asia/Australia) and go forward one calendar day (regardless of the time of day).
E.
Coordinated Universal Time (UTC):
· Essentially, this is the official Global Time (i.e. the time on Earth). It is an official reference for all nations. It used to be called Greenwich Mean Time.
· Kept with extremely accurate atomic clocks.
· UTC time always refers to the time at the Prime Meridian – it is NEVER adjusted for daylight savings.
· UTC minus 8 equals Pacific Standard Time (in winter); UTC minus 7 equals Pacific Daylight Time (in summer). If you have Pacific Time and want to convert to UTC, add instead of subtract.
F.
Daylight Savings Time (an
energy saving practice):
In the summer months, this policy moves our waking/working hours into the actual daylight hours. For example, if the sun normally goes down at around 7:00pm during the summer, people will begin turning lights on. But, with daylight savings time we move the clocks ahead so that the sun goes down around 8:00pm. This way we save an hour’s worth of energy by not turning on lights.
Maps and Geospatial Technologies
I.
Cartography: Cartography is the art and science of making maps.
A.
Map:
· A map is a flattened, reduced representation of the spherical Earth.
· Maps are never completely accurate; there is always some distortion.
· The only truly correct representation of the shapes of the Earth’s land masses is a globe.
B.
Projections: Maps were originally created by “projecting” shadows from a lighted globe onto paper or other material. The shadows were then traced to create the map.
1.
Projections cause distortion of:
a)
Shape
b)
Area (or Size)
c)
Distance
d)
Direction
2.
Types of Projections:
a)
Cylindrical: Best known is the Mercator Projection, which causes area to appear increasingly larger than it actually is as latitude increases (compare Africa and Greenland on a globe and then on a Mercator projection).
b)
Planar (see text)
c)
Conic (see text)
C.
Scale: A map is a reduced picture of the true Earth. Scale indicates the amount of reduction. Larger scale maps will show more detail and make things look larger, while small scale maps will show less detail and make things look smaller.
1.
Written Scale (see text)
2.
Graphic Scale (see text)
3.
Representative Fraction (see text)
II.
Geospatial Technologies
A.
Remote Sensing: Refers to images and data collected at a distance from Earth’s surface (e.g. images taken from airplanes, satellites, the space shuttle, or the international space station). Widely used in weather forecasting, but important to many disciplines and activities which study environmental systems.
B.
Global Positioning System (GPS): Consists of a network of 24 space based
satellites
which communicate with
receivers
on the ground to provide and record exact location data.
C.
Geographic Information System (GIS):
· A computer system for entering, storing, manipulating, analyzing, and displaying spatial data. All data is digital!!!
· Combines digital maps (computerized maps) with a database of information about the features displayed in the map.
|
# |
Sample Questions: |
| 1 |
The Equator is a: A. meridian of latitude B. parallel of longitude C. meridian of longitude D. parallel of latitude |
| 2 |
Which location on the geographic grid actually exists in the real world? A. 135°N Lat. & 122°W Long. B. 87°S Lat. & 70°W Long. C. 35°S Lat. & 185°E Long. D. 85°S Lat. & 220°W Long. |
| 3 |
If you travel directly north from the South Pole, your: A. Longitude will increase. B. Longitude will decrease. C. Latitude will decrease. D. Latitude will increase. |
| 4 |
How many hours does it take the earth to rotate exactly 45( on its axis? |
| 5 |
If it is 5pm Monday in New York City, what time is it in Sacramento? |
|
6 |
Assume that you are traveling across the Pacific Ocean from Australia to Los Angeles. If it is Tuesday January 21 JUST BEFORE I cross the international date line, what will the date be JUST AFTER I cross the international date line? A. Wednesday January 22 B. Friday October 19 C. Monday January 20 D. Tuesday January 21 |
| 7 |
What time and date was it in California when it was 11:00 UTC on July 25, 2009? A. 18:00 PDT on July 26, 2009 B. 19:00 PDT on July 25, 2009 C. 04:00 PDT on July 25, 2009 D. 03:00 PDT on July 25, 2009 |
| 8 |
Which map scale is considered smallest and would show the least detail of any particular place? For instance, at which scale would the State of California appear smallest and show the least detail? A. 1:26,000,000 B. 1:8,000,000 C. 1:400,000 D. 1:26,000 |
| 9 |
Due to the rotation of the Earth, solar noon seems to migrate (move) across the globe during the day. Which direction does it move? A. East to West B. West to East C. North to South D. South to North |
GOOD NEWS!!!
The practice questions above – plus
many,
many more – can be found in the online practice quizzes discussed in your syllabus and in class. You can take each quiz multiple times, and each time you will get some new questions. Once submitted, the quizzes are graded automatically, with the correct answers provided immediately.
This is a great way to prepare for the exams!!!
(SERIOUSLY, TAKE THE ONLINE PRACTICE QUIZZES!!!)
TIP: Review
online notes
before every lecture! TIP: Review
your notes as soon as possible
after every lecture!
John Aubert • American River College Location, Time, Maps, and Technology
Physical Geography Lecture Notes Page 1 of 3
aubertj@arc.losrios.edu
TIP: Review online notes before every lecture! TIP: Review your notes as soon as possible after every lecture!
Location and Time
I. Location – The Geographic Grid: In order to better measure and navigate around Earth and
evaluate global environmental phenomena, humans have imposed a grid system over the entire
globe. These are the parallels of latitude and the meridians of longitude.
A. Parallels of Latitude (measures degrees north and south of the Equator):
Imaginary Circles (reference points) drawn on the globe perpendicular to the axis (side to
side) to measure angular distance in degrees North or South of the Equator. Lat = Flat
1. Angular Distance: Angular distance is a distance measured in degrees as
opposed to miles or kilometers. Latitude is measured in degrees north or south of
the Equator. Each degree of latitude is approximately 110 km (70 miles),
2. Equator: The line of latitude which perfectly bisects the globe between the north
and south poles is called the Equator; it is designated as 0°Latitude.
B. Meridians of Longitude (measures degrees east and west of the Prime Meridian):
Imaginary Circles drawn on the globe between the North and South Poles. They are used to
measure angular distance in degrees East or West from the Prime Meridian. They cross all
parallels of latitude at right angles.
1. Angular Distance: Longitude is measured in degrees east or west of the Prime
Meridian. At the Equator one degree of longitude is approximately 110 km (70
miles); this steadily decreases approaching the poles.
2. Prime Meridian: This is the meridian designated as 0°Longitude. Decided
arbitrarily. Passes through the old Royal Observatory at Greenwich, England.
C. Combining Latitude and Longitude: A correct location on the geographic grid
must give Latitude (North OR South) AND Longitude (East or West). Sacramento, California
is located at approx. 39° North Latitude and 121° West Longitude
II. Time
A. Earth’s Rotation:
Earth rotates on its axis, which is an imaginary line passing through Earth from the north
pole to the south pole.
One rotation takes approx. 24 hours (rotates 15 degrees per hour)
The direction of rotation is toward the east.
B. Solar Noon: Solar noon refers to the moment when the sun is at its highest point in the
sky, generally occurring around clock Noon. Solar noon “travels” or “migrates” from east to
west across the globe (as does sunrise and sunset).
C. Time Zones (see map in text):
A time zone is an area where everyone agrees to observe the same time, regardless of
the position of the Sun.
There are 24 primary time zones, each being 15° of longitude wide. Many countries
modify this system; it is ultimately political.
Each time zone has a controlling meridian (the exact longitude where solar noon and
clock noon are the same).
John Aubert • American River College Location, Time, Maps, and Technology
Physical Geography Lecture Notes Page 2 of 3
aubertj@arc.losrios.edu
TIP: Review online notes before every lecture! TIP: Review your notes as soon as possible after every lecture!
D. International Date Line:
Located at approx. 180° Longitude in the Pacific; exists to prevent the “impression” of
time travel.
Travel eastward across it (toward the Americas) and go backward one calendar day
(regardless of the time of day).
Travel westward across it (toward Asia/Australia) and go forward one calendar day
(regardless of the time of day).
E. Coordinated Universal Time (UTC):
Essentially, this is the official Global Time (i.e. the time on Earth). It is an official
reference for all nations. It used to be called Greenwich Mean Time.
Kept with extremely accurate atomic clocks.
UTC time always refers to the time at the Prime Meridian – it is NEVER adjusted for
daylight savings.
UTC minus 8 equals Pacific Standard Time (in winter); UTC minus 7 equals Pacific
Daylight Time (in summer). If you have Pacific Time and want to convert to UTC, add
instead of subtract.
F. Daylight Savings Time (an energy saving practice): In the summer months,
this policy moves our waking/working hours into the actual daylight hours. For example, if
the sun normally goes down at around 7:00pm during the summer, people will begin turning
lights on. But, with daylight savings time we move the clocks ahead so that the sun goes
down around 8:00pm. This way we save an hour’s worth of energy by not turning on lights.
I. Cartography: Cartography is the art and science of making maps.
A. Map:
A map is a flattened, reduced representation of the spherical Earth.
Maps are never completely accurate; there is always some distortion.
The only truly correct representation of the shapes of the Earth’s land masses is a globe.
B. Projections: Maps were originally created by “projecting” shadows from a lighted globe
onto paper or other material. The shadows were then traced to create the map.
1. Projections cause distortion of:
a) Shape
b) Area (or Size)
c) Distance
d) Direction
2. Types of Projections:
a) Cylindrical: Best known is the Mercator Projection, which causes area to
appear increasingly larger than it actually is as latitude increases (compare
Africa and Greenland on a globe and then on a Mercator projection).
b) Planar (see text)
c) Conic (see text)
John Aubert • American River College Location, Time, Maps, and Technology
Physical Geography Lecture Notes Page 3 of 3
aubertj@arc.losrios.edu
TIP: Review online notes before every lecture! TIP: Review your notes as soon as possible after every lecture!
C. Scale: A map is a reduced picture of the true Earth. Scale indicates the amount of
reduction. Larger scale maps will show more detail and make things look larger, while small
scale maps will show less detail and make things look smaller.
1. Written Scale (see text)
2. Graphic Scale (see text)
3. Representative Fraction (see text)
II. Geospatial Technologies
A. Remote Sensing: Refers to images and data collected at a distance from Earth’s
surface (e.g. images taken from airplanes, satellites, the space shuttle, or the international
space station). Widely used in weather forecasting, but important to many disciplines and
activities which study environmental systems.
B. Global Positioning System (GPS): Consists of a network of 24 space based
satellites which communicate with receivers on the ground to provide and record exact
location data.
C. Geographic Information System (GIS):
A computer system for entering, storing, manipulating, analyzing, and displaying spatial
data. All data is digital!!!
Combines digital maps (computerized maps) with a database of information about the
features displayed in the map.
# Sample Questions: Questions similar to these will be on your exam. As you study you should
anticipate how I might use these questions to create new questions on the same concepts.
1 The Equator is a: A. meridian of latitude B. parallel of longitude C. meridian of longitude D. parallel of latitude
2
Which location on the geographic grid actually exists in the real world?
A. 135°N Lat. & 122°W Long. B. 87°S Lat. & 70°W Long.
C. 35°S Lat. & 185°E Long. D. 85°S Lat. & 220°W Long.
3
If you travel directly north from the South Pole, your:
A. Longitude will increase. B. Longitude will decrease.
C. Latitude will decrease. D. Latitude will increase.
4 How many hours does it take the earth to rotate exactly 45° on its axis?
5 If it is 5pm Monday in New York City, what time is it in Sacramento?
6
Assume that you are traveling across the Pacific Ocean from Australia to Los Angeles. If it is Tuesday January 21 JUST BEFORE I
cross the international date line, what will the date be JUST AFTER I cross the international date line?
A. Wednesday January 22 B. Friday October 19 C. Monday January 20 D. Tuesday January 21
7
What time and date was it in California when it was 11:00 UTC on July 25, 2009?
A. 18:00 PDT on July 26, 2009 B. 19:00 PDT on July 25, 2009
C. 04:00 PDT on July 25, 2009 D. 03:00 PDT on July 25, 2009
8
Which map scale is considered smallest and would show the least detail of any particular place? For instance, at which scale would the
State of California appear smallest and show the least detail?
A. 1:26,000,000 B. 1:8,000,000 C. 1:400,000 D. 1:26,000
9 Due to the rotation of the Earth, solar noon seems to migrate (move) across the globe during the day. Which direction does it move?
A. East to West B. West to East C. North to South D. South to North
GOOD NEWS!!! The practice questions above – plus many, many more – can be found in the online practice quizzes discussed in
your syllabus and in class. You can take each quiz multiple times, and each time you will get some new questions. Once submitted, the
quizzes are graded automatically, with the correct answers provided immediately. This is a great way to prepare for the exams!!!
(SERIOUSLY, TAKE THE ONLINE PRACTICE QUIZZES!!!)
-
Maps and Geospatial Technologies
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