Explain how the main components of the Earth system (atmosphere, 
oceans, biosphere and solid earth) influence each other, and give examples. 

Explain the distinction between a one-way coupling and a feedback and the distinction between a positive and a negative feedback. 

Be able to figure out whether a feedback loop is positive or negative. 

Explain how positive or negative feedbacks influence the stability of a system. 

Name and explain at least one major feedback loop influencing Earth's climate. 

Explain how, and under what conditions the daisies acted to keep the temperature of Daisyworld within a range that was conducive for them to survive. 

SAMPLE EXAM QUESTION: If summer rainfall is below normal for an extended period of time, vegetation tends to wilt or die. As the vegetation wilts or dies, less moisture evaporates from the underlying soil.  If there's less evaporation, the air is likely to be drier and weather systems are likely to produce less rain when they pass through. Is this a positive or a negative feedback loop?  Explain your answer. 

ANSWER: A decrease in summer rainfall results in futher decreases in rainfall. The initial effect is amplified, and this is thus a positive feedback loop. You can also draw the couplings and resulting feedbacks.

2) Radiation and the greenhouse effect 

Be able to name the key factors influencing a planet's effective radiating temperature, and know how they relate qualitatively
EXAMPLE: If the albedo goes up, then the effective radiating temperature of the planet goes ____. 

Compare the distances from the sun, the albedoes, and the effective radiating temperatures of Earth, Mars and Venus.

Understand quantitatively the inverse square law.
EXAMPLE: If a planet is twice (or half) as far from the sun as is Earth, its solar flux is __ times as much. 

Explain how the angle of the sun in the sky affects that amount of solar radiation incident on a horizontal surface. 

Understand quantitatively Wien's law.
EXAMPLE: If a planet is twice (or half) as hot as the Earth, it emits most of its radiation at a wavelength __ times as long as the Earth does. 

Understand quantitatively The Stefan Boltzmann law.
EXAMPLE: If a planet is twice (or half) as hot as the Earth, it emits __ times as much radiation as the Earth does. 

Be able to qualitatively describe the greenhouse effect and distinguish it from human induced global warming. 

Be able to name the most important greenhouse gases. 

Be able to name the major gaseous constituents of the Earth's atmosphere. 

Explain why summers are warm and winters are cold. 

SAMPLE EXAM QUESTION: Venus is closer to the sun than the Earth, yet it has a lower effective radiating temperature than the Earth does.  Explain. 
ANSWER: Venus is cloud covered and therefore has a much higher albedo than the Earth has, which means that it reflects back to space more of the incident solar radiation without absorbing it.

3) Convection in the atmosphere 

Be able to describe how temperature varies with height in the Earth's atmosphere and be able to distinguish between troposphere and stratosphere. 

Explain how we know that convection transports energy upward. 

Explain how convection transports energy upward. 

Explain why air expands as it rises. 

Explain why condensation occurs in rising air, rather than in sinking air.

Understand the effect of temperature on relative humidity and convection.
EXAMPLE: Why does relative humidity usually drop during the morning hours and rise during the evening? 

Explain how the release of latent heat in clouds makes in possible for convective plumes to rise higher than they would be able to if the atmosphere were dry and had the same lapse rate as the observed atmosphere. 

Define lapse rate. What is the dry adiabatic lapse rate? 

What is a temperature inversion?

SAMPLE EXAM QUESTION: If the relative humidity is 25% and it ascends dry adiabatically in a convection plume, by approximately how much will it rise before it becomes saturated? (hints: the dry adiabatic lapse rate is about 10°C/km and the saturation mixing ratio doubles for every 10°C increase).
ANSWER: Saturation is reached when the relative humidity is equal to 100%.  The relative humidity is defined as 100 x w/w_s.  As the air rises, the water vapor mixing ratio remains the same (w=constant), but temperature decreases at a rate of 10°C/km.  This results in a decrease in the saturation mixing ratio, w_s.  To go from 25% to 100% relative humidity, w_s has to decrease by a factor of four.  This corresponds to a decrease in temperature by 20°C (w_s doubles for every 10°C increase).  Based on the adiabatic lapse rate, a 20°C decrease in temperature is reached by a 2 km increase in altitude.  The air parcel will this reach saturation after it rises by 2 km. 
 

4) Atmospheric circulation 

Understand why radiation provides a surplus of energy in the tropics and a deficit in the polar regions. 

Explain how motions in the atmosphere transport energy poleward, and describe the two kinds of motions involved (the Hadley cell and migrating cyclones at higher latitudes). 

Describe the major atmospheric circulation features such as the trade winds, the ITCZ, the subtropical anticyclones, the mid latitude surface westerlies, the monsoons, and the storm tracks and relate them to climate in various parts 
of the world. 
 

5) Describing and interpreting climate 

Explain the distinction between weather and climate. 

Give some examples of climate statistics (winter and summer mean 
temperature, mean annual rainfall, the lowest temperature on record...) 

Explain why, around latitudes of 20-40 degrees, the western sides of continents tend to be drier than the eastern sides, especially during Summer. 

Explain why cities located in the interior of continents have harsher climates, with larger Winter/Summer temperature contrasts, than coastal cities. 

Describe how mountains influence climate and give examples. 

For a hypothetical continent, you should be able to sketch the major climate zones and describe the climate in a given location.

SAMPLE EXAM QUESTION:
Match the following climate statistics (temperature and precipitation) with the locations: 

A  Quito, Ecuador (0°S; 9000 ft.) 
B  San Diego, CA  (32°N) west coast 
C  Tokyo, Japan (36°N;  east coast) 
E  Melbourne, Australia (38°S; east coast)
 
 

	JAN	FEB	MAR	APR	MAY	JUN	JUL	AUG	SEP	OCT	NOV	DEC
1)T(°F)	56	58	58	62	63	66	70	72	70	66	62	58
r(mm)	48	38	39	20	4	1	0	2	3	9	31	44
2)T(°F)	39	39	44	56	62	70	75	79	74	62	52	43
r(mm)	48	63	106	135	147	165	142	153	234	208	97	56
3)T(°F)	56	56	56	66	56	56	56	56	56	56	56	56
r(mm)	99	112	142	176	137	43	20	30	69	112	97	70
4)T(°F)	68	68	64	59	54	50	48	52	56	58	62	64
r(mm)	48	46	56	58	53	53	48	48	58	66	58	58

Quito is also easy to spot because it is the only equatorial station. Station #3 with its conspicuously uniform temperatures year round; cool because of the altitude, is the only one that fits. 

That leaves Tokyo and San Diego, on the opposite sides of the Pacific.  San Diego should have a dry summer and Tokyo a relatively wet summer.  Hence, Station #1 must be San Diego and Station # 2 must be Tokyo.) 

 Last Updated:
01/22/2002