Helens+Notes+and+Research

= Greenhouse Effect - First Edition = toc September 6, 2010

The radiation from the sun gets either absorbed or reflected by the Earth. But when excess radiation that was suppose to be reflected back into space gets trapped by atmospheric gases such as Carbon Dioxide, the Earth heats up. This is known as the Greenhouse Effect.

= Greenhouse Effect - Second Edition = October 6, 2010

The radiation from the sun gets either absorbed or reflected by the Earth. The reflection of sun radiation depends on the albedo of Earth's surface. Forests and dark colored surface have low albedo, so they absorb a lot of sunlight. While light colored surface, the ocean and ice have high albedo so they reflect most of the sunlight. Also, the Earth acts as a Black body that absorbs sunlight and releases IR radiation. Heat in form of IR radiation emitted then gets trapped by the Greenhouse gases such as Carbon Dioxide in the atmosphere so the Earth heats up. This is known as the Greenhouse Effect.

= The Goldilock's Principle = September 11, 2010

The Earth, Venus and Mars are three planets that are well situated to benefit from the energy output of the sun, yet all 3 have very different atmospheres and surface conditions. Scientists who first probed the potential of increased greenhouse gases effects on Earth’s climate looked for clues about our future by examining the conditions on our nearest neighbors. = =
 * == Atmospheric Gas == || == Venus == || == Earth == || == Mars == ||
 * Carbon Dioxide (percent) || 96.5% || 0.03% || 95% ||
 * Nitrogen (N2) || 3.5% || 78% || 2.7% ||
 * Oxygen (O2) || Trace || 21% || 0.13% ||
 * Argon (Ar) || 0.007% || 0.9% || 1.6% ||
 * Methane (CH4) || 0% || 0.002% || 0% ||
 * Surface Pressure - Relative to the Earth ( in bars) || 90 || 1 || 0.007 ||
 * Major Greenhouse Gases (abbreviated to GHG) || CO2 || H2O, CO2 || CO2 ||
 * Actual temperature (C) || 477 || 15 || -47 ||
 * Temperature if no GHG (C) || -46 || -18 || -57 ||
 * Temperature due to GHG ( C) || +523 || +33 || +10 ||

What do you think explains the differences between Earth and its neighboring planets?
The composition of the atmosphere and the distance from the sun are two important factors that contributed to the differences among Earth, Venus and Mars. The Carbon Dioxide concentration in the atmospheres of Venus and Mars is significantly higher than that of the Earth. This probably accounts for the the high temperature in Venus since the Greenhouse Gases raised the temperature by 523 degrees Celsius. Although with similar concentration of Carbon Dioxide, Mars does not experience the same high temperature because it's further from the sun so the intake of the sunlight would be much lower. In addition, Earth has a much higher concentration of Nitrogen in the atmosphere.

References:
"Activity 1 Teacher Guide: The Goldilocks Principle." //UCAR | Understanding Atmosphere, Earth, and Sun | Home//. Web. 11 Sept. 2010. .

= = = Questions 1 & 2 = September 11, 2010

Question 1:
How many joules of enegery are required to run a 100 W light bulb for one day?

1 W = 1 J/s 100 W = 100 J/s 24 hrs = 86,400s 100 W = 8,640,000 J/day How much cola has to be burned to light the bulb for one day?

30,000,000 J/kg x 0.3 = 9,000,000 J/ kg 8,640,000 J/day / 9,000,000 J/kg = 0.96 kg/day

Question 2:
1 acre yields about 20,000 ears of corn 1 acre = 4046.85642 square meters 4.186 J = 1 calorie 1 ear of corn = 160,000 calories

Sunlight: 250 W/m^2 = 21,600,000 J/m^2 per day x 90 days = 1.944e9 J/m^2

Corn: 160,000 calories x 4.186 J = 669760 J/ear 669760 J/ear x 20,000 ears = 1.34e10 J/acre 1.34e10 J/acre / 4046.85642 m^2 = 3,310,026.01 J/m^2

Efficiency: 3,310,026.01 J/m^2 / 1.944e9 J/m^2 = 0.001703 or 0.2%

=Chapter 3. The Layer Model =

1) What does Fin = Fout mean in this model. Use your own words

Fin represents the incoming energy flux as sunligh, and Fout represents the outgoing energy flux as IR radiation. The Layer Model assumes that the incoming energy and the outgoing energy are the same.

 2) Why do you measure the size of the shadow cast by the Earth when the Sun shines on it to calculate the intensity of the energy heating the Earth?

The size of the shadow represents the area of the Earth absorbing sunlight. The intensity of energy (I) is calculated by:

I = Fin (W) / A (m^2 )

So divide by the area by the incoming energy flux to calculate the intensity of energy.

3) Show the calculations to determine the temperature of Venus and Mars using the data in TABLE 3.1. Are these the measured temperatures on Venus and Mars? Why or Why not?



These are not measured temperatures on Venus and Mars because the Layer Model assumes that there is no greenhouse effect. However, in reality with the presence of the greenhouse gases, the temperatures would probably increase.

= Chapter 3 Part II = 1. Verify in your own words and, if you would like, with a diagram, that the budget equation for the layer model of the earth’s overall energy is equal to the sum of the budget equations for the ground and the atmosphere. Why is it important that this be true for our model calculations? (See explanation between pages 23 and 25).



Since, Iup, atmosphere + Idown, atmosphere = Iup, ground Iin, solar + Idown, atmosphere = Iup, ground

Therefore, Iup, atmosphere + Idown, atmopshere = Iin, solar + Idown, atmopshere Iup, atmosphere = Iin, solar

According to the calculations above Iup, atmosphere = Iin, solar. Another to way to think about this is understanding the Law of Conservation of Energy. The Law of Conservation of Energy states that energy cannot be created or destroyed, so the amount of energy coming in as sunlight has to eventually equal to the amount of energy leaving the atmosphere. Then the system will be equilibrium.

2. What is the “skin temperature” of the Earth, and why is it significant to the development of the layer model?
The "skin temperature" of the Earth is the temperature between the ground and the atmosphere. I t includes the atmosphere - from the surface of the Earth to the top of the atmosphere. The temperature is equal to the amount of solar radiation (//I// solar) substracting the //I//up,atmosphere temperature. The "skin temperature" is significant because it's the temperature of the Earth accounting the Greenhouse Effect. I don't quite get what you mean here. Can you clarify?

3. Respond to question #1 on page 27
a = 12% Isolar = 1350 W/m^2 (same as the Earth?) б = 5.6704e-8

Temperature of the moon: {(1-0.12)(1350)/(4)(5.6704e-8)}^(1/4) = 269K

= Lab Daisyworld Questions  =

1. In the first scenario, "DaisyWorld in 3 species", you'll notice that the living area ("total daisies") doesn't exceed 70%. Look at the Parameters of this scenario. The deathrate is set to 0.3, which may explain the living percentage being no more than 0.7. Play with this parameter. What does the deathrate do to the daisies' ability to control their environment's temperature? To the species mix?

As the deathrate increases, the daisies' ability to control their environment's temperature decreases significantly.

2. Using a multispecies scenario you like, run the insulation from 0 to 1.0 by .2's. What effect does this have on the daisies' control of the planet temperature? Why? If DaisyWorld had spatial structure, neighboring patches of daisies, and the neighbors were more influential (lower insulation) than the planetary temperature, what might be different?

As the insulation value increases, daisies' control of the planet temperature increases. Higher insulation means more types of daisies are covering more areas, so the actitives of the plants would control the temperature more effectively.

3.Another parameter is "max steps per". At each luminosity increment, DaisyWorld runs "to convergence", or a maximum of "max steps per" calculations at that luminosity, before plotting a point. Try setting this down from 1000 to 5. Where does the result differ from the original scenario? Try DaisyWorld in 5 species with max steps set to 1, 2, 3, 4, 5, 20, 50, 100. Speculate on what's going on. (Note: this is a deterministic simulation, no random component. The exact same parameters yield identical results.



As the max convergence step value decreases from 1000 to 1, daisies' ability to control the temperature decreases restricting to a smaller range of solar luminosity. In addition, the area that the different daisies covered changed.

=Chapter 4 Questions=

a. Is 10 addition ppm of methane in the atmosphere more or less imrpotant than 10 additional ppm of CO2 in the atmosphere at current concentrations?
Methane has less important because the temperture is higher when there is 10 addition ppm of CO2 as compared when there is 10 addition ppm of Methane.