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What are the evidence of sphericity?
- -Photos rom moon, earth orbit, satellite images.
- -Disapperance of ships over the horizon
- -Shadow of earth on moon during an eclipse
- -Pythagoras (587-507 BC) concluded that the eart was sphere revolving on a fixed point.
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Who is Eratosthenes?
He calculated the earth's polar circumfernce using simple geometic principles.
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What is Syene?
City near tropic of Cancer. Which has no shadow at noon on the longest day.
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How did Eratosthenes calculate earth's polar circumference?
Eratosthenes compared city of Syene and Alexandria on longest day. Alexandria on longest day shadow is 7.2 degrees.
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What is a geoid?
Oblong 3D shape that resembles a sphere.
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What shape is the earth?
A geoid. [bulges at the equator]
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What is latitude?
Angular distance from equator to North and South Pole.
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What is longitude?
Angular distance from Prime Meridian to East and West.
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How are latitude and longitude measured?
Degrees, minutes and seconds.
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Where is the Prime Meridian?
Greenwich, England at Royal Observatory.
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What is the International Dateline?
180 degrees east or west from Prime Meridian. It divides the globe into different days.
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What are great circles?
A plane intersecting the globe along a great cirlce divides the globe into equal halves and passes through the center.
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What are small circles?
A plan that splits the globe into unequal sections and does not pass through the center of the globe.
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What are parallels?
A line connecting points along the same latitude. Parallels get shorter toward the poles.
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What is the equator?
The equator is the longest parallel and is also a great circle. The only great circle that is a latitude measure. Angle measure of the equator is 0 degrees.
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How many degrees of longitude or latitude is an hour?
15 degrees
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What are the different types of map projection representations?
- Distance
- Direction
- Area
- Shape
- Proximity
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What does an equidistant map projection portray?
Accurately portrays distances from the center of the projection to another place on the map.
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What does an azmuthal map projection portray?
Direction
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What does an equal area map projection portray?
Areas that have the same proportional relationship.
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What does a conformal map projection portray?
Shape; map scale is the same in any direction.
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What is a proximal map?
When the relationship between distance on a map and the same distance on the earth is preserved.
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What is a Mercator Projection?
Cylindrical map that is conformal, but area at higher latitudes are distorted. Rhumb lines are portrayed as straight lines.
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Describe Albers Equal Area Projection
- Conic
- Areas portrayed accurately, but shapes are distorted.
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Describe Planar Projections (gnomonic)
Created by projecting the earth's image onto a flat plane. Great circles are projected as straight lines.
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Describe Oval Projections (Robinson)
Created using complex calculations rather than the purely physical approach. Represents a compromise between equal area and true shape.
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What are rhumb lines?
Lines of constant heading or direction.
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What are two properties of rhumb lines?
Look like straight lines on Mercator projection [Great circle lines look curved]. And opposite on gnomonic projection.
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What does GPS stand for?
Global Positioning System
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How does GPS work?
Calculates position by measuring the distance between itself and three or more satellites. [Time delay for the signal to travel] Microwave signals used.
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What are the two types of Remote Sensing?
Active RS and Passive RS
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What is Active RS?
Direct energy at the earth, by the sensor, and observe the character of the energy reflected back to the remote sensing platform.
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What is Passive RS?
Record the character energy radiated from the earth's surface (no energy is emitted by the sensor)
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What is GIS?
Geographic Information Systems
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What are GIS used for?
This computer software system organizes spatial information and produces digital maps in layers that can be combined of viewed separately.
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What is Perihelion?
Earth's closest position to the sun during its orbit.
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What is Aphelion?
Earth's furthest position from the sun during its orbit.
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Five reasons for seasons:
Revolution, Rotation, Tilt, Axial Parallelism, and Sphericity.
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Dates of season change:
- Winter Solstice; December 21-22
- Vernal Equinox; March 20-21
- Summer Solstice; June 20-21
- Autumnal Equinox; September 22-23
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What is fusion?
The process where superheated atoms of hydrogen are forced together.
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What is solar wind?
Gaseous flow of energy that flows out from the sun.
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Describe the relationship between wavelength and energy.
Shorter wavelength means more energy is being emitted.
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What does insolation mean?
Intercepted Solar Radition
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What is transmission?
The passage of energy through the atmosphere or water.
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What is the solar constant?
The average value of insolation at the thermopause: 1,372 W/m2
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Four paths solar radiation can take:
Scattering, refraction, reflection, or absorption
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What is albedo?
The measure of reflectivity an object has.
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What is Net Radiation?
- The final outcome of radiation of earth's surface.
- [(+SW) + (-SW)] + [(+LW) + (-LW)] = Net R
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What are some temperature controls?
Latitude, altitude, cloud cover, and land-water heating.
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What is the Continental Effect?
Inland locations have greater range in daily and seasonal temperatures because land is a better conductor for heat.
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What is the Maritime Effect?
Coastal locations have a smaller range in daily and seasonal temperatures because ocean helps regulate heat.
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What are isotherms?
Lines of equal temperatures on a map.
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