Definition of a System:
An assemblage of interrelated parts that work together by way of some driving process(es)
o Exchanges of energy and/or matter via input and output processes
o Operating together as a whole; the sum of many interacting parts
o Inputs and outputs enter and leave the system
o Inputs loop around continually in the system
o System feedback
o System equilibrium
Example of a Monday Night Football Game:
o Input of Energy Sources: profile, prestige, motivation
o Input of Material: food, people
o Outputs: press stories, tear up the field, radio broadcast, school reputation, money, injuries
o Subsystems: officials, teams, coaches, traffic control, vendors, home crowd, pedocabbies...
o Holiday season of 1968 and Apollo 8 mission looking back at the earth from the moon
o Boost to environmental movement view that we need to protect the earth. Prior to the environmental movement, dumping trash and industrial waste was accepted by the general population
o Perception so common now that view of Earth from Mars was no big deal for those under 35
o Atmosphere: realm of air (Gr. atmo)
o Hydrosphere: realm of water (Gr. hydro)
o Lithosphere: realm of solid earth (Gr. litho)
o Biosphere: realm of life (Gr. bio)
o Pedosphere: realm of soil (L., from ped, soil)
Sources of Energy & Matter
o Energy – from solar radiation (insolation) that keeps earth warm
o Energy – occasional asteroid impacts that contributed to dinosaur extinction, generated tremendous energy. But we get substantial energy from asteroid and other small object impacts on a regular basis (like Meteor Crater)
o Matter – chemicals in all subsystems, for example Fe
o Matter – from extraterrestrial impacts (water?)
Transfer of energy and matter by earth-surface processes
Organization of class...
o Earth’s Place...parameters, measures, technology
o Lithosphere (EX)
o Hydrosphere (EX)
o Atmosphere (EX)
o Different Physical Landscapes
o Biosphere (EX)
Transfer of energy and matter produces regional patterns
What can you give as examples?
o Case 1
o Case 2
o Case 3
Sidebar Speculation about Mars:
o There is also a lot of speculation about life in the ice on Mars
o Rock coatings may provide evidence of life in the new Lander missions
**We know Earth is the place where life exists because liquid water allows chemical reactions**
2. Lethal Radiation Stopped: example of Ozone Shield
Sidebar on what would happen if we lost our magnetosphere?
o As magnetospheres go, Earth is not special: Mercury, Jupiter, Saturn, Uranus, and Neptune all have magnetospheres
o Mars is the real mystery: it is pretty cold and is quite like Earth in many ways...so why no magnetosphere?
o Mars lost its overall magnetism, when the molten iron in the core solidified
o Mars may have lost life and its atmosphere when the magnetosphere no longer protected Mars a solar wind that stripped its atmosphere!
Do you believe in extraterrestrial life?
You see the idea everywhere
NASA VIEW has changed
o James Lovelock created concept of GAIA (named after Greek Goddess of Earth), that the earth is like an organism that is self-regulating and keeps itself in a constant state (not an experiment of mice)
o Example: Faint Sun Hypothesis
o Example: Ozone layer is produced by positive feedback & then equilibrium
IV. Solar Radiation
A. Solar Furnace
o Fusion drives solar energy
o Very little reaches the Earth
B. Characteristics of Solar Output:
o Sometimes confused about what is a wavelength
o Shorter than visible
o Longest: radio and microwave
o Focus for this class is difference between short and long wavelength radiation
Nuts and bolts of long and short wave radiation
C. What’s the point?
o Solar Energy!!! (“Insolation”: INcoming SOLar radiATION)
o Reaches the Earth in the form of radiant energy, and makes up 99.987% of the energy received by the Earth
o So...understanding how solar energy varies is important to this class, your grade, where you live, where you may want to vacation or explore, and whether you can answer that age old question of why we have seasons!
V. Earth’s Dimensions & Spatial References
A. Earth’s Size & Shape
o “3rd Rock from the Sun”
o 5th largest diameter (~8,000 miles [12,900 km])
o Measuring the Earth (247 BCE!)
o Earth’s maximum relief
B. Spatial References on Earth
o Two important reference points
o Geographic grid; network of intersecting lines (coordinates); “Cartesian”
o Lines of longitude (“meridians”)
o Put them together...
Earth’s Orbit: Parameters, Tilt & Seasonality
o Complete circling of the sun
o On the Plane of the Ecliptic...
o You knew this from Hollywood!
o 365 and 1/4 days (approximately)
o Orbit is slightly elliptical
o Perihelion (closest/January): 91.5 million miles
o Aphelion (farthest/July): 94.5 million miles
o So...tell me why its summer in July?
o And, how–WHY–does the earth revolve around the sun? [Newtonian old-school vs. Relativism quantum-school]
o Not a perfect sphere that rotates
o About 24 hours (23 hours & 56 minutes - unless you are ready to be the source of a joke... )
o “Rising” and “setting” of the sun (does the sun actual “rise” or “set”?)
o Counterclockwise rotation when looking down at north pole or from outer space (clockwise when looking from south pole)
o Responsible for Coriolis Effect
o Helps us keep time:
So what’s the difference again?
Sidebar on Earth’s Moon
o Moon rotates in sync with the Earth
o Experiences “libration“ because tidally locked to Earth
o There is no “dark side of the moon” (apologies to Pink Floyd)
o We only see about 59% of Moon’s surface at any one time (larger view)!
o Axis and tilt is always parallel to itself no matter where it is in the orbit (axis currently points to North Star—Polaris—but shifting...)
o Mars has variation in obliquity also
4. Earth’s Orbit changes at timescale of thousands of years:
o May also affect your astrological sign—depending on if you follow the Tropical Zodiac (or “Western”, synced with seasons) or the Sidereal Zodiac (or “Eastern”, synced with constellations)
o CNN article discussing overall astrological concept
And these likely caused glacial-interglacial fluctuations by changing location and amount of solar radiation...
**More on these parameters’ interaction and cycles when we get to the climate section, but here’s a primer**
1. The key latitudes you must know to understand seasons...
4. Closer look at solstice and equinox as they go through the seasons
o Northern hemisphere toward the sun
o Tropic of Cancer - 23.5 degrees North - overhead sun
o Antarctic Circle@ 66.5 degrees South - 24 hours night at and to the south
o From outer space – just night allows you to see aurora australis
o Southern Hemisphere toward the sun
o Tropic of Capricorn - 23.5 degrees South - overhead sun
o Antarctic Circle @ 66.5 degrees South - 24 hour daylight
o Arctic Circle @ 66.5 degrees North - 24 hour night
o Where could this photo be taken?
o But lower angles as you go poleward
Seasons are MAINLY created by earth’s tilt which varies incoming solar radiation (insolation). And that’s determined by:
o Solar elevation (sun angle)
o Length of Day
And these both depend on: Latitude and Time of Year
Sooooo: How would one of the nation’s “most prestigious” universities’ graduates, faculty, and alumni answer the BIG Question?
**SUMMARY movie of how sun angle and length of day changes throughout the year**
WHAT’S YOUR NOON SUN ANGLE?
90 - latitude where you are +/- latitude where sun is 90 degrees at noon (“subsolar point”)
o If sun’s subsolar point and your location are in different hemispheres, ADD
o If sun’s subsolar point and your location are in same hemispheres, SUBTRACT
How do I know the subsolar point?
o December 22 solstice: Tropic of Capricorn (23.5 degrees S)
o March 22 equinox: Equator (0 degrees)
o June 22 solstice: Tropic of Cancer (23.5 degrees N)
o Sept 22 equinox: Equator (0 degrees)
o Extreme example:
o 22 December (winter solstice)...where’s the subsolar point?
o You just won a trip to Oulu, Finland (latitude = 64 degree N)
o What’s the angle of the sun at noon?
o Subsolar point & your location are in different hemispheres, so ADD: 64 + 23.5 = 87.5
o Noon Sun Angle = 90. Thus, 90 - 87.5 = 2.5 degrees (the sun would be 2.5 degrees above the horizon at noon)
o Equation looks like this: 90 - (64 + 23.5)
o Denver Example:
o Latitude ~39 degrees. Noon sun angle for today is?
o So...90 - (39 +/- x) = noon sun angle for Denver today (could check with a sextant)
Why should I care?
o To know where not to live
o To understand Groundhog Day
o Because high angles make some places warm for migration
o At Stonehenge: on what side are the shadows?
In New Zealand: are the melting snow patches facing north or south? What exposure protects the snow from the sun?
C. Other Ways to Visualize:
o If you were the sun, looking straight down (90 degrees) at the subsolar point (latitude at which sun is directly overhead at noon), this would be how the year would seem (movie)
o NOTE: from our vantage point, the sun is overhead twice each year BETWEEN the tropics of Capricorn and Cancer
o COOL VIEW: If you looked at earth for one year, this movie is the way the tilt would affect the division between night and day
· So...who has the surplus/deficit?
· Why don’t the poles freeze and the equator cook?