ANSWER-- Toba super volcanic eruption being studied using **O2 isotopes in quartz
crystals**
- largest eruption observed
- located in Indonesia
- ca 73,000 years ago
**researching why eruption was so large**
Why do we care about the climate? - ANSWER-- climate is influenced by many parts of
the earth
Climate - ANSWER-- average surface conditions over LONG time scale
(min ~ 10 years, typical is 50, 100, 1000 years)
Weather - ANSWER-- average surface conditions over SHORT time scale
(hours, days, weeks)
Climate on earth is... - ANSWER-- complicated, not simple
- varies in different parts of the earth
What influences climate? - ANSWER-- oceans, plate tectonics, biosphere
*not just atmosphere*
System Interactions - ANSWER-- interactions among all climate-influencing
components are complicated to untangle
Feedbacks - ANSWER-- interactions where one component changing causes other
changes, then original component changes again
Positive Feedback - ANSWER-- every time cycle is completed, cycle is repeated
ex: when A increases, B changes, A increases again (temp incr, ice melts, temp incr
more)
*doesn't always have to be increase
,(temp decr, ice forms, temp decr more)
**hard to break out of cycle**
Negative Feedback - ANSWER-- when cycle is completed, next time through cycle,
opposite result occurs
ex:
1-when A incr, B decr
2-when B decr, A incr
(next time through)
3-A decr, B incr
4-B incr, A decr
(back to step one)
**creates a stabilizing see-saw effect**
(neither A or B gets too high/low)
What controls climate? - ANSWER-- energy/heat is needed to change climate
Insolation - ANSWER-- energy from the sun that reaches the earth
* "incoming" + "solar" + "radiation" *
- several things affect how much insolation the earth receives
Aphelion - ANSWER-- variation in insolation
- max distance earth is from the sun
* 152 million km from the sun *
Aphelion picture - ANSWER-
Perihelion - ANSWER-- variation in insolation
- min distance earth is from the sun
* 147 million km from the sun
Perihelion picture - ANSWER-
Milankovitch Cycles - ANSWER-- cause variation in insolation
- 3 cycles:
1. Eccentricity
2. Obliquity (tilt)
3. Precession
Eccentricity - ANSWER-- Milankovitch cycle
- looks at shapes of earths orbit
- switches back and forth from eccentricity min and max ~ every 50,000 years
- cycle is 100,000 years
Eccentricity Maximum - ANSWER-- ellipse shape
Eccentricity Minimum - ANSWER-- circular shape/pattern
Obliquity (tilt) - ANSWER-- Milankovitch cycle
- tilt of earth on its axis
- "rocks" back and forth by 2 degrees
- cycle is ca 41k years (takes ~ 20k yrs to "rock back") *(where season are on planet)*
How much does the obliquity angle change? - ANSWER-- ~ 2 degrees
- think of rocking chair
How much does the obliquity angle change the insolation? - ANSWER-- significantly
- reason why we have opposite seasons in N and S hemispheres
Seasonal Contrast - ANSWER-- how different summer vs winter temperatures are
High Obliquity Angle - ANSWER-- completely "rocked" back
, - high seasonal contrast
Low Obliquity Angle - ANSWER-- low seasonal contrast
Precession - ANSWER-- Milankovitch cycle
- 3-D "wobbling" motion, tilted earth rotating around straight, vertical line (creates circle)
- takes ~ 11k years to get 1/2 way through cycle (1/2 way is when seasons flip months,
full cycle ~ 22k yrs)
What does precession affect? - ANSWER-- time of year *(WHEN)* you experience each
season
True or False: The Milankovitch cycles can synchronize to balance or cancel. -
ANSWER-True.
- note: cycles have different time scales
How does the atmosphere control climate? - ANSWER-- Albedo
Albedo - ANSWER-- measure of reflectivity, how much energy is going to be lost
- in atmosphere
What does energy react with to result in a loss of insolation? - ANSWER-- w/ gasses
- clouds
- ground surface
**this totals to a loss of 30% of insolation**
How does Atmospheric Gas control climate? - ANSWER-- atmo-composition gasses
- greenhouse effect
Atmo-Composition gasses - ANSWER-- Nitrogen, 78%
- Oxygen, 21%
- rest is greenhouse gasses: can get insolation close to surface and traps some of it
Greenhouse Effect - ANSWER-- works b/c wavelength is changed
** insolation wants to re-radiate back into space **
Why are greenhouse gasses a big deal if they are present in small amounts? -
ANSWER-- effective at what they do
- do not need large amounts to trap insolation
- w/o greenhouse gasses, temp would drop by 33 degrees celsius and the earth would
freeze
Why are the N and S poles colder than the tropics? - ANSWER-- insolation changes
with latitude
- light from sun is hitting equator head on, very concentrated in a small area
- light that hits poles falls over a large area
Example of how insolation changes with latitude? - ANSWER-- poles are colder than
tropics
Latitudinal Insolation Distribution - ANSWER-- need to relocate/refocus concentrated
energy
Hadley Cells - ANSWER-- atmospheric circulation cell, takes heat from equator to ~30
deg latitude
How does Atmospheric Heat Transport control climate? - ANSWER-- Hadley Cells
- Ferrel Cells
- Polar Cells
Ferrel Cells - ANSWER-- pushes heat higher than 30 deg latitude
Polar Cells - ANSWER-- pushes heat higher than Ferrel Cells