ASSIGNMENT 2_DS - Chapters 12-17................... Assigned 14 March 2003 ...................Due date: April 4 2003.

This assignment is designed ONLY for DISTANCE STUDIES students.

** Please note that all references to the text book refer to the sixth edition. If you do not have that edition, you will need to obtain a copy, or access it in your library. Not having the text is not an excuse for not doing the question. If it is absolutely necessary (and this will only happen if you provide me with a really good excuse), you can ask me to fax you the relevant pages.

1.  Match the descriptions below to the letters (a) to (n). Some answers may be used more than once, and some of the letters may not be answers to any questions. You may consult your text book.

(i) This front is drawn in red on a weather map.
(ii) Suggests that a front is regenerating or strengthening.
(iii) The spin of air parcels.
(iv) Small disturbances embedded in a longwave.
(v) Lines connecting points of equal pressure change.
(vi) Forecasting method that assumes that weather systems wil move in the same direction and at the same speed as they have been moving.
(vii) These use mathematical equations to describe the atmosphere's behaviour.
(viii) This indicates that the atmospheric conditions are favourable for the development of hazardous weather.
(ix) An enormous thunderstorm that can maintain itself for many hours.
(x)Thunderstorms that develop in a line, one next to the other, each in a different stage of development
(xi) A second surge of electrons that proceeds from the base of the cloud toward the ground during a thunderstorm.
(xii) The zone of intense thunderstorms around the centre of a hurricane
(xiii) Weak trough of low pressure in the tropics along which hurricanes occasionally form.
(xiv) Either solid particles or liquid droplets that remain suspended in the air.
(xv) A pollutant that comes primarily from the burning of sulfur-containing fuels.
____________________________________________________________________
(a) Steady State / trend method.
(b) cold front
(c) supercell storm
(d) weather watch
(e) frontogenesis
(f) isallobars
(g) particulate matter
(h) vorticity
(i) sulfur dioxide
(j) Multicell thunderstorm.
(k) dart leader
(l) foreign agent
(m) eye wall
(n) Easterly wave (tropical wave)
(o) shortwave
(p) atmospheric model
(q) warm front

2.  Give the name, and a description of the temperature and moisture characteristics, for the following types of air masses: cP, cT, cA, mP, and mT. Also discuss the origins of each type. Finally, sometimes a third symbol is added to this nomenclature - describe what extra information this symbol usually gives.

3.  Answer the following multiple-choice questions. You may consult your text book.

(i) When an upper-level low lies directly above a midlatitude storm system, the surface low will usually _________________ .

              a. dissipate
              b. intensify
              c. show no change during a 48 hour period
              d. deflect rapidly toward the northeast
              e. turn into a high pressure system.

(ii) According to the polar front theory of a developing wave cyclone, a storm system is usually most intense:

              a. as a stable wave
              b. as a stationary front
              c. as an open wave
              d. as a frontal wave
              e. when the system first becomes occluded.

(iii) If a forecaster gives a "degree of confidence" with his or her weather forecast, then the forecaster used a forecasting technique called:

              a. steady-state or trend
              b. climatology
              c. persistence
              d. analogue
              e. ensemble

(iv) Outside you look up and notice two cloud layers above you. The lower cloud is moving from a westerly direction, while the higher cloud layer is moving from a southerly direction. From this observation you conclude that the wind is ______________ with height and ___________________ advection is occurring between the cloud layers.

              a. veering, warm
              b. veering, cold
              c. backing, warm
              d. backing, cold

(v) Acid rain can:

              a. cause a chemical imbalance in the soil
              b. disfigure outdoor fountains, sculptures and statues
              c. damage plants and water resources
              d. all of the above.

4. Short calculations: 
(a) A lightning stroke is seen and 5 seconds later thunder from the stroke is heard. How far away was the lightning? (You may need to look up a value for the speed of sound, and decide a suitable temperature).
(b) A tornado is moving towards the east at a speed of 20 metres per second. The wind at the edge of the tornado's rotating vortex is rotating at a speed of 50 metres per second. Calculate the speed of the wind on the (i) north, (ii) east, (iii) south and (iv) west sides of the suction vortex. What "F"-number would you give this tornado according to the Fujita scale?
(c) Winds in a hurricane near the equator reach speeds of 80 metres per second at a radius of 40 km from the hurricane centre. What is the centripetal acceleration experienced by a particle in this region? How does this acceleration compare to the Coriolis acceleration at a typical latitude of 60 degrees north? [Hint: you will need to look up other earlier chapters to find the relevant equations to do these calculations e.g. chapter 9]

5.  The temperature profile over a city in the early afternoon takes the following form. At the surface the temperature is 20 degrees centigrade. The temperature decreases at a rate of 9 degrees centigrade per kilometre until an altitude of 120 metres is reached. It then increases at a rate of 6 degrees centigrade per kilometre for a further vertical extent of 200 metres. Above that height it decreases at a rate of 6 degrees centigrade per kilometre up to an altitude of 500 metres. Beyond that, we have no interest in its profile for this question.
(a) Draw this profile on a graph. Be sure to get the heights at which the temperature changes, and the values of the temperature at these turning points, correct.
(b) Which partof this graph refers to the "mixing layer"?
(c) Specify the heights of the base and top of the inversion layer.
(d) In what height range would you expect to see the greatest concentration of pollutuants?
(e) Suppose that by late afternoon the surface air temperature increases by 2 degrees centigrade. Draw a second graph indicating what you might expect the new temperature profile to look like (approximately only). Particularly pay attention to whether you woulde expect the depth of the mixing layer to increase or decrease. Also indicate whether you would expect the density of pollutants within the mixing layer to increase or decrease. Explain.

6.  State whether the following questions about hurricanes (and related phenomena) are true or false.


(a) Hurricanes may contain tornadoes.
(b) The vertical structure of a hurricane shows an upper-level outflow of air, and a surface inflow of air
(c) A strong trade wind inversion can inhibit the formation of intense thunderstorms and hurricanes
(d) Tropical cyclones that form over the eastern North Pacific Ocean adjacent to the west coast of Mexico are called hurricanes
(e) Hurricanes can only form over water
(f) In the centre of a hurricane the surface air pressure is much higher than the air pressure around the periphery of the eye
(g) Squall lines do not form in the tropics
(h) In the heat-engine model, energy for a developing hurricane is taken in at the surface, converted to kinetic energy, and lost at the cloud tops through radiational cooling
(i) A hurricane moving north over the Pacific Ocean adjacent to the west coast of North America will normally survive as a hurricane for a longer time than one moving north over the Atlantic ocean adjacent to the east coast of North America.
(j) Hurricanes do not form over the South Atlantic Ocean adjacent to South America because of the relatively cold water found there and the unfavourable position of the ITCZ.
(k) In the eye of a hurricane, several kilometres above the surface, the air is sinking.
(l)The organized convection theory proposes that for a hurricane to form, the thunderstorms must become organized so that the latent heat that drives the system can be confined to a limited area.

7. 









The above diagram represents a springtime surface weather map with a warm front and a cold front associated with an open-wave cyclone. Answer the following questions that pertain to the diagram.
(a) Near which number is the most likely place for a squall line to develop?
(b) At which number are thunderstorms most likely to develop?
(c) A boxed-off area representing a tornado watch area would most likely be placed near which number?
(d) Number "3" represents a boundary called what (2 words)?
(e) If tornadoes should form near number 3, they would most likely move in which direction?

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