Test 1 Review Flashcards
Explain the difference between closed, open, and isolated systems and give short examples of each.
An open system exchanges both matter and energy with other systems. An example might be a lake – heat is exchanged between the surroundings and the lake, and water is constantly coming in and leaving. A closed system exchanges energy, but not matter. An imperfect example is the earth – for the most part, the earth doesn’t lose mass to outer space, but it does emit energy in the form of longwave radiation. Finally, an isolated system exchanges neither energy nor matter with any other system. An example is the universe as a whole – no other perfectly isolated system exists.
Positive and negative feedbacks are common features of environmental systems. Describe the main features of positive and negative feedbacks and illustrate and explain each with one (1) example.
Positive feedback loops occur when conditions cause change in a system, and this change itself encourages the continuation of similar changes. An example might be the melting of the polar ice caps – the albedo of ice is much higher than that of water, so as the ice melts, more and more of the sun’s radiation is absorbed by the water at the poles, causing the ice to melt faster. Positive feedback loops often occur in situations that were unstable metastable – changes in conditions can disrupt the equilibrium, causing a runaway reaction. A negative feedback loop is when the system is in a stable state. Any changes to conditions are countered by the system in such a way that the changes are minimized. For example, as the earth warms, the amount of longwave radiation it emits also increases, which slows the overall warming.
What kind of equilibria exist in environmental systems?
Steady state, dynamic, cyclical and episodic equilibria are present in environmental systems. In steady state equilibria, there may be small changes over time, but the overall trend is one of no change. To contrast, in a dynamic equilibrium, there are also small changes over time, but they build into an overall trend of growth or decline. Cyclical equilibria follow a pattern of growth and then decline and then growth again over time, continuing in this manner. Episodic equilibria are mostly constant, but are characterized by being punctured by large, infrequent anomalies in the pattern of consistency.
Explain what shortwave and longwave radiation are, and from what they are emitted in the context of global energy budgets.
Both shortwave and longwave radiation are forms of electromagnetic radiation, carrying energy through space. Shortwave radiation (UV radiation) is emitted by the sun, and is absorbed by the atmosphere and other parts of the earth. To release this excess energy that is absorbed by the sun, the earth emits longwave radiation (IR radiation) into space. If the energy budget were “balanced”, energy absorbed by the sun would be equal to energy released back into space as longwave radiation. However, some of this longwave radiation is absorbed by gases in the atmosphere, warming the earth in the “greenhouse effect”.
What are some factors that affect the amount of insolation the earth (as a whole) receives over the year? Give at least three answers – there are four explanations we covered in class.
The earth’s orbit is elliptical, so when it is at the point on its orbit furthest from the sun, it receives less insolation on average. The earth is also tilted, and has some wobble in its tilt, both of which affect which regions of the earth may receive more insolation on average than other areas of the earth. Finally, increased sunspot activity can temporarily increase the amount of solar radiation received by the earth.
Give a brief overview of the structures of the atmosphere and how these relate to incoming and outgoing radiation. How does the atmosphere produce a greenhouse effect? Give at least three examples of a greenhouse gas and explain what makes these gases “greenhouse gases”.
The atmosphere is composed of several layers, varying in gas composition and temperature greatly. One important layer of the atmosphere, the ozone layer, is located in the stratosphere and has a high concentration of ozone gas relative to other parts of the atmosphere. This layer serves to protect us from dangerous, higher energy elements of incoming solar radiation. In terms of outgoing radiation, increased concentrations of gases that absorb IR radiation (such as CO2, methane, or water vapour) can produce a warming “greenhouse” effect because these gases will intercept the Earth’s outgoing longwave radiation and turn it back to heat rather than allowing it to be emitted into space.
Give the net radiation equation and explain what each component means, including latent heat. What is sensible heat?
Q*=QE+QH+QG – net radiation equals latent heat flux from evaporation + sensible heat transfer into the atmosphere + heat conduction into ground. Sensible heat is heat that can be measured with a thermometer – a measure of the kinetic energy of ambient molecules. Sensible heat transfer is positive when energy is given to the earth and negative when it leaves the earth.
Surface Radiant Energy Balance equation
Q*=K?-K?+L?-L? - Net radiation equals shortwave in (insolation) minus shortwave out (reflection), plus longwave in (absorbed longwave) minus shortwave out (longwave radiated out).
Why do Bedouins wear black robes in the desert? What is the difference between black robes and white robes in the desert?
Although we might think there would be a difference in heat due to the ability of the pigments to absorb or reflect heat, for the Bedouins, there is no difference in bodily temperature of one wearing a white robe compared to a black robe. The surface of the fabric will be a different temperature, but both of the robes enable convection of air through the bottom of the robe, distributing heat and keeping the wearer cool.
Explain what they are, and then give major global patterns, for latent heat of evaporation and sensible heat. Why do these patterns occur?
Latent heat of evaporation is the amount of heat transferred to the surrounding environment when water evaporates. It is high near areas of ocean convection where very warm water is moving into colder areas, like in the gulf stream and the Kuroshio current. It is lower when you get further inland, and especially in deserts, because there is less water there to even be evaporated to share its heat. Sensible heat is the direct transfer of heat from one medium to another without changing the volumes of the media. It is high in deserts, where heat is being absorbed without changing the surface. An interesting anomaly for sensible heat is that it is negative in a stretch of ocean from the southern atlantic to the southern indian, where the water is absorbing heat from the atmosphere.
What are the general global patterns of Net Radiation at the Earth’s surface and what explains these patterns?
In terms of net radiation, there is a net gain of energy at the equator, since this receives constantly strong insolation. Contrast this with the poles, which have a net negative radiation, meaning they release far more longwave radiation than they receive from the sun as insolation. This is due to lower amounts of insolation at the poles due to the earth’s tilt (produce great seasonal differences in insolation at the poles) and its spherical shape (equivalent amounts of insolation are spread over much larger areas near the poles than they would be at the equator, so an area at the equator is warmer).
What is the Coriolis effect and how does it change global atmospheric circulation patterns? What is the effect this produces?
The Coriolis effect is produced by the rotation of the earth, and it causes air masses that appear to be moving straight towards the poles from our frame of reference to actually be moving in a diagonal sort of direction from an observer outside the earth. This effect is largest near the equator, where a point on the earth is moving the fastest due to the earth’s rotation. The Coriolis effect is responsible for interesting phenomena like the intertropical convergence zone, and it also produces the pattern of westerlies/trade winds.
What is thermohaline circulation? In which system, and in what locations, can it be found? What is its major effect? What is the anomaly that thermohaline circulation causes in heat transfer (we discussed it in class)?
Thermohaline circulation belts are a global series of currents in the ocean that circulate warm, shallow currents towards the poles, where they become cold and salty, sinking and becoming deep currents. It is sometimes referred to as “a global conveyor belt”. An example where it can be found is at the gulf stream, but it runs all over the world. The function of this mechanism is to facilitate transfer of heat from the equator to the poles, keeping the earth in thermodynamic equilibrium. The upwelling of cold water, causing negative sensible heat in the south Atlantic and Indian oceans, is due to a thermohaline belt.
Give an overview of atmospheric lifting mechanisms, and how these relate to patterns of rainfall.
Convergent lifting, convectional lifting, orographic lifting, frontal lifting. Convergent lifting: two air masses meet in a low pressure area and rise, e.g. ITCZ. Convectional lifting, air mass moving inland from maritime to continental region warms as it moves inland, this heating causes it to rise. Orographic lifting: air masses are pushed up against a mountain, rising with the mountain. On the other side of the mountain, the descending air mass is heated by compression and remaining water evaporates. Frontal lifting: warm air meets cold air and warm air rises up above the cold front.
Give an overview of the Koppen climate classification. How did Koppen come up with his categories?
The Koppen climate classification is a rigid system of classification that assigns a region with a two-letter (sometimes three) code that describes the temperature and level of precipitation at the region. The first letter, ranging from A at the equator to E at the poles, describes temperature. The second (and third) letter(s) is/are used to describe the level of precipitation experienced by the region. Using this short code, a general idea of the climate of the region can be expressed.
What are El Nino and La Nina? Explain how they work in detail, and what effects they generate.
El Nino and La Nina are anomalies in wind and water circulation patterns over the pacific that result in abnormally warm conditions (in the case of El Nino) or abnormally cold ones (in the case of La Nina). They are measured using sea surface temperature readings. Typically, cold surface sea water and winds move east to west, rising on the west pacific and causing rain. In El Nino, this pattern is reversed; the sea currents and surface winds move west to east, and rain occurs on the eastern pacific coast. La Nina is a stronger version of the typical east to west pattern.
