exam 4: heating the atmosphere

Explain what occurs when solar radiation is scattered. Compare the 1) path, 2) intensity, and 3) type of radiation before and after each of these processes.

It changes direction as it hits small particles in the air; the path is longer and more spread out, the intensity is weaker, and the type of radiation changes from direct light to softer diffused light

Explain what occurs when solar radiation is reflected. Compare the 1) path, 2) intensity, and 3) type of radiation before and after each of these processes.

It bounces off a surface; the path changes direction, the intensity stays about the same if the surface is shiny, and the type stays as direct light but goes in a new direction

Explain what occurs when solar radiation is absorbed. Compare the 1) path, 2) intensity, and 3) type of radiation before and after each of these processes.

Taken in by the surface; the path stops at the surface, the intensity drops because the energy is used or changed, and the type changes from light to heat

Describe how scattering in the atmosphere results in a blue sky by day and a red sunset at night.

It makes the sky look blue during the day because blue light spreads more, and at sunset, the sky can look red because the sunlight travels farther and the blue is mostly scattered away

What is diffuse light?

Light that has been scattered by clouds or particles in the air, making it soft and spread out

Explain why there is still some light rather than complete darkness in the shadow of a tree.

Diffuse light from the sky and around the tree spreads into the shadow

Review Figure 16.24. What is the albedo of a substance?

The amount of sunlight a surface reflects; higher means more light is reflected

What substances in the earth’s atmosphere have a high albedo?

Clouds, ice, and snow because they reflect a lot of sunlight

What is global dimming?

Slowing of earth warming because air pollution blocks some sunlight from reaching the ground

Explain how global dimming may have caused the steady or slightly declining temperatures between 1945 and 1975.

The amount of pollution in the air blocked sunlight which reduced the earth's warming

Why did the temperature begin to change after 1970 (Think CAA)?

Stricter rules reduced air pollution, allowing more sunlight to reach the earth

What gases in the atmosphere are good absorbers of ultraviolet radiation? Infrared radiation?

Ozone is good for UV and carbon dioxide and water vapor are good for IR

What type of radiation do these gases re-emit? Why?

Infrared radiation absorbs energy from the sun and releases it as heat to warm the atmosphere

List and explain the three ways that energy is transferred from the earth’s surface back into the atmosphere. Which one is the highest by percentage?

Radiation- energy emitted as heat; convection- warm air rises; evaporation- heat is used to turn water into vapor, which rises and carries energy with it; convection has the highest percentage (50%)

Is the Earth’s energy input equal to the total energy output? Explain.

Yes, energy from the sun is balanced by the energy the earth radiates back into space

Note that the earth absorbs and releases 503 W/m2 yet it only receives 340W/m2 from the sun. How is this possible?

This is due to the greenhouse effect, the gases trap some of the outgoing energy, causing the atmosphere to reflect heat to the earth’s surface, leading to more energy being released than absorbed

List the three ways humans can alter Earth’s Energy Budget and cause changes in the Earth’s climate.

Increasing greenhouse gas emissions, changing land use, aerosol pollution

What is the current average surface temperature of the earth’s atmosphere?

15 degrees Celsius

 How much cooler would the Earth's atmosphere be without the greenhouse effect? How would this change the planet?

Without them, the atmosphere would be 30 degrees cooler making the planet to cold to support life

Compare the greenhouse gasses H2O and CO2.

H2O is the strongest greenhouse gas but can change quickly, but CO2 is weaker and stays in the air much longer and helps warm the earth

How long does each gas last on average in the atmosphere?

H2O 3 days, CO2 1,000 years, CH4 10 years, and NOx 1 day

5. Which one is a more effective greenhouse gas?

H2O because it traps heat

6. Which one accounts for a higher percentage of the Greenhouse effect?

H2O with 60%

7. Which gas is a feedback gas? Forcing gas? Explain the difference.

H2O is feedback and CO2 is forcing; forcing gas directly affects the earth temperature by adding or removing energy but feedback gas is influenced by temperature changes and can either amplify or reduce those changes

8. Methane is a very potent greenhouse gas. It lasts only 10 years in the atmosphere but can increase in global temperatures for more than 100 years. Explain why.

It causes a lot of warming and these affects last longer because it triggers other gases like water vapor to stay in the air

9. Review Figure 13.4. Explain the concept of climate forcing.

Is when something changes the balance of energy coming in and out of Earth, causing the climate to warm or cool

10. Distinguish between Natural and Human Forcing. Are the following greenhouse gases in the atmosphere the result of Natural Processes, Human Action, or both: CO2, CH4, NOx, CFCs, and HCFCs?

CO2: natural and humans; CH4: humans (cows) and natural; hydrocarbons and NOx are humans

11. Explain the difference between positive and negative forcing.

Positive warms the earth by adding energy while negative forces cool the earth by blocking or removing energy

12. Explain why ozone is both a positive and negative forcing depending on where in the atmosphere it is located.

Positive when it is low in the air and can trap heat but negative when it is high up and blocks the sunlight (this cools the earth)

13. Distinguish between Direct and Indirect aerosols.

Direct reflects the sunlight and indirect helps form clouds that also reflect sunlight

14. Are forcings from solar radiation a significant factor in the current warming trend?

No, most of it is caused by human activities like burning fossil fuels

15. Review Figures 13.2 and 13.3. Distinguish between positive and negative feedback in the earth’s energy budget.

Positive adds energy to the earths system that causes warming and negative takes energy away and causes cooling

16. List an example of both types of feedback(negative and positive).

Positive: Melting ice makes earth warmer because less sunlight is reflected; Negative: more clouds can cool earth by blocking sunlight

17. Which one amplifies, and which one diminishes climate change negative or positive feedback?

Positive makes climate change stronger and negative makes it weaker

18. Explain the Ice Albedo Feedback Loop. Is this a positive or negative feedback loop? Why is this very significant in the development of ice ages?

It is a positive feedback loop because when ice melts, it reflects less sunlight, making earth warmer and melting even more ice, which is important in ice ages because it can speed up warming or cooling