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RGPL 103 Global Cities:Planning and Development
Dr. Hoch
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Earth’s Orbit Around Sun
152.5 Million Km 147.5 Mil. Km
SUNEARTH
AphelionJuly 6 (12:00)
PerihelionJan 3 (00:00)
Dates for 2010
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Earth Rotation
23 1/2°
Ecliptic Plane(Plane of earth revolution around sun)
Earth’s axis
N Pole
Northern Hemisphere Seasons
• Summer• North pole tilted toward Sun• Days are longer than the nights• Get more energy - higher temperatures
• Fall• Neither pole tilted toward the Sun• Days about equal with nights• Less energy than in the summer• Cooler temperatures
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Northern Hemisphere Seasons cont.
• Winter• North pole tilted away from the Sun• Days shorter than the nights• Get less energy-Cold temperatures
• Spring• Neither pole tilted toward the Sun• Days about equal to nights• More energy than winter- Warmer temperatures
Global regions
• Tropics (23 ½°N ‐ 23 ½°S)
• Low latitudes (30°N ‐ 30°S)
• Mid latitudes (30°N ‐ 60°N and 30°S ‐ 60°S )
• High latitudes (60°N ‐ 90°N and 60°S ‐ 90°S )
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Key positional relationships
•Tropic of Cancer - 23 1/2° N•Highest latitude in the Northern Hemisphere that the suns
vertical rays ever reach
•Tropic of Capricorn- 23 1/2° S•Highest latitude in the Southern Hemisphere that the suns
vertical rays ever reach
•Arctic circle- 66 1/2° N•24 hrs of daylight-summer solstice•24 hrs of darkness at winter solstice
•Antarctic circle- 66 1/2° S•24 hrs of daylight-winter solstice•24 hrs of darkness at summer solstice
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Circle of illumination
Equinoxes and Solstices (2010)
Day Date Sub‐solar Point
Summer solstice June 21 23 1/2° N
Autumnal equinox Sept 23 0°
Winter solstice Dec 21 23 1/2° S
Vernal equinox March 20 0°
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Equinox
Solstices
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Earth
1
3
1
1
= 100%
= 33.3%
SUN
Higher latitudes get LESSENERGY per unit of area
Solar Heating
Most of the Sun’s Energy is Received in the Equatorial Region of the Earth
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Global‐scale circulation system
• The equatorial and tropical regions receive far more solar energy than the midlatitudes and polar regions
• This heat energy is redistributed from warmer to colder areas by means of atmospheric air circulation (60%) and ocean currents (40%)
Hypothetical non‐rotating earth circulation
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Idealized global circulation
The global circulation model
Consists of three ‘cells’1) Tropical cell2) Midlatitude cell3) Polar cell
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Midlatitude and subtropical jet streams
Cross‐sectional view of jet streams
BLUE arrows and lines represent
areas or fronts of HIGH pressure
and rotate clockwise
RED arrows and lines represent
areas or fronts of LOW pressure
and rotate counter-clockwise
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Cyclic changes in upper air flow
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Inter‐Tropical Convergence Zone (ITCZ) World Map
The Intertropical Convergence Zone (ITCZ)
The location of the ITCZ gradually varies with the seasons, roughly corresponding with the location of the thermal equatorAs the heat capacity of the oceans is greater than air over land, migration is more prominent over land Over the oceans, where the convergence zone is better defined, the seasonal cycle is more subtle, as the convection is constrained by the distribution of ocean temperatures
The Intertropical Convergence Zone (ITCZ), known by sailors as the doldrums or the calms, is the area encircling Earth near the Equator, where the northeast and southeast trade winds converge
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Worldwide Rainforest Depletion
• Reported in 2012, more than 200,000 acres of rainforest are
burned every day
• That is more than 150 acres lost every minute of every day, or 78
million acres lost every year
• More than 20 percent of the Amazon rainforest is already gone
• More is severely threatened as he destruction continues
TropicOf
Cancer
TropicOf
Capricorn
Amazon BasinRain Forest
Congo BasinRain Forest
South EastAsiaRain Forest
Rainforests also help to stabilize Earth's climate
They absorb carbon dioxide
The reduce the effects of worldwide anthropogenic climate change
They also home to about half of the species of plants and wildlife on the planet
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https://news.mongabay.com/2014/12/tropical‐deforestation‐could‐disrupt‐rainfall‐globally/
The Earth at NightMan‐made light shining at night is used as a metric to measure the amount of urban development
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Central Place Theory
• Provides a conceptual mechanism for understanding the role of the city as a service center.
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