Download Test 2 - Skule

CIV300TerrestrialEnergySystems,2016F
Test2QuestionSheet
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Test2
Aid Sheet Exam: A single 8.5 by 11 inch aid sheet (both sides) and Type 2 nonprogrammablecalculatorsarepermitted.ThetimeallowedforthisTest(PartAplus
PartBcombined)is90minutes.Answersaretobewrittenontheanswersheetgiven
NOTonthisquestionsheet.
PARTA
1. A rising air mass will be conditionally stable if:
(a) The environmental lapse rate > dry adiabatic lapse rate
(b) The environmental lapse rate = dry adiabatic lapse rate
(c) The saturated adiabatic lapse rate > the environmental lapse rate > dry adiabatic lapse
rate
(d) The saturated adiabatic lapse rate < the environmental lapse rate < dry adiabatic lapse
rate
ANSD
2. The monsoon is primarily caused by:
(a)
(b)
(c)
(d)
A large scale convection cell bring moist air into land
High insolation over the downstream direction of the moving moist air mass
Instability over the land
All of the above
ANSD
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3. What is the dew point of an air mass with a dry bulb temperature of 25 C and a relative
humidity of 60%?
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(a) 17 C
(b) 0.012 kg per kg of dry air
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(c) 19.5 C
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(d) 25 C
ANSA
4. A Large river carrying snowmelt in spring empties out into the ocean. The fresh water stays
on top of the ocean water due to its lower density. If the fresh water forms a layer 10 cm
deep, calculate the pressure 1m below the water’s surface. The density of seawater is 1,025
-3
kgm and the atmospheric pressure is 101,000 Pa.
(a) 10,020 Pa
(b) 111,020 Pa
(c) 111,045 Pa (d) 109,212.4 Pa
ANSB
5. Calculate the specific gas constant for the atmosphere on a newly discovered planet that
consists of 40% N2 (molar mass of 28), 20% CO2 (molar mass of 44) and 40% O2 (molar
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mass of 32). R = 8.314 Jmol K .
(a) 32.8 gmol
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(b) 253 Jkg K
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c) 0.253 Jkg K
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(d) 3.946 Jkg K
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CIV300TerrestrialEnergySystems,2016F
Test2QuestionSheet
ANSB
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6. An air mass with a dry bulb temperature of 10 C and a relative humidity of 40% cools down
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overnight. If the air temperature drops to -10 C overnight, which of the following will occur?
(a) The air mass will be unstable and will rise
(c) Dew will form on the ground, then freeze
(b) Frost will form on the ground
(d) It will rain, then slow
ANSB
7. A basement gets flooded during a rainstorm. After the water has drained away, the resulting
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air inside the basement has a relative humidity of 100% and a dry bulb temperature of 15 C.
The basement is left over a few days. During that time the air’s relative humidity drops to 70%
as it begins to dry out with its walls and floor absorbing moisture. What is the room’s resulting
dry bulb air temperature?
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(a) 20.5 C
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(b) 15 C
(c) 18.5 C
(d) It will not change as no energy is added
ANSC
8. The wet bulb temperature is:
1.
2.
3.
4.
How warm it will feel if the air is saturated
Always less than the dry bulb temperature
A direct and proportional measure of an air mass’ enthalpy
Higher when air density decreases
(a) 1&2&54
(b) 3&4
(c) 1only
(d) 1&3
ANSC
9. Which of the following statements is not correct?
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(a) At some point all the water in a deep lake in a cold climate will be 4 C
(b) The warmest water is always found at the top of a lake
(c) Ice always floats
(d) The coldest water is at the bottom of a lake in tropical regions
ANSB
10. On opposite sides of the Earth in the northern hemisphere, two rotating air masses have
identical pressure gradient forces acting between their edges and their centre. One is a
centre of high pressure, the other is a centre of low pressure. What will be a key difference
between wind speeds found circulating 20 km from their centres, sufficiently high above the
ground to negate surface friction?
(a) Wind speeds will be faster around the centre of high pressure
(b) There are no differences other than direction. Wind speeds will be identical.
(c) Winds will be counter-clockwise around the centre of high pressure
(d) Wind will be towards the centre of the low pressure but not the high-pressure system
CIV300TerrestrialEnergySystems,2016F
Test2QuestionSheet
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ANSA
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11. The temperature at ground level is 25 C while it is -15 C at 3,000 m of altitude. What is the
saturated adiabatic lapse rate?
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(a) 6 C per 1,000 m
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(b) 9.8 C per 1,000 m (c) 13.3 C per 1,000 m (d) It cannot be found
ANSD
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12. If saturated air rising up in a cumulonimbus cloud decreases in temperature from 28 C to
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5 C, how much energy is released?
(a) 72 kJ per kg of dry air
(c) 11.0 kJ per kg of dry air
(b) 90 kJ per kg of dry air
(d) It depends on the air’s final relative humidity
ANSA
13. Continued from q.12, what percentage of the air mass’ moisture will condense out as a result
of this cooling?
(a) Cannot be calculated
ANSB
(b) 78%
(c) 57%
(d) 22%
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14. A vehicle is traveling due west at a latitude of 50 N at a velocity of 100 kmh . To a stationary
observer in space (and concentrating only on the rotating Earth and not its orbital journey
through space), how fast does the car appear to be traveling? Recall the Earth’s diameter is
12,750 km.
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(a) 100 kmh
(b) Cannot be known without calculating the Coriolis force
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(c) 1,173 kmh
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(d) 973 kmh
ANSD
CIV300TerrestrialEnergySystems,2016F
Test2QuestionSheet
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PARTB
1.
Identify four key characteristics of jet streams and the conditions that result in their
formation. (2 marks)
ANS Fast moving air due to high pressure gradient force
Narrow band of air as that PGF only exists in a small location
Air flowing perpendicular to the pressure gradient due to Coriolis force
Found at intersections of air masses with high pressure differences high in the
atmosphere due to proximity of adjacent cells (e.g. polar to Ferrel, Ferrel to Hadley cell)
2.
Explain, with the aid of diagrams, why the polar cell exists within the Earth’s atmosphere
and why it results in steady, prevailing surface wind patterns at ground level. (4 marks)
ANS As there is no solar energy in winter, and even in summer it is low, so cold dense air
forms over the pole. As it is denser than air to the south it flows south. It then diverts to
the right (W) due to the Coriolis force.
3.
Identify five key requirements for the development of an Atlantic hurricane. Detail how
they impact the storm’s growth. You may use a diagram to help illustrate your answers. (5
marks)
ANS
§
§
§
§
§
§
§
§
4.
An unstable atmosphere. This will allow release of latent energy through
adiabatic cooling resulting in condensing water vapour that provides the storm’s
energy.
Warm ocean water. This is the source of that moisture which strong winds pick
up. Don’t need a specific temperature.
A centre of low pressure to draw air inwards
The Coriolis force. That turns air to the right of the storm’s centre of low pressure
as it is drawn into it.
Prevailing winds. These take the hurricane over fresh sources of warm water.
Needs to stay over water. Storm cannot gain energy over land as there is no
source of moisture.
Pressure imbalance vertically at the storm’s centre. This allows more air to leave
than is drawn in, thus resulting in dropping central pressure and increasing
pressure gradient forces.
Low wind disturbance above the storm, allowing it to remain in form and not be
disrupted.
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Air with a temperature of 14 C and a relative humidity of 50% at ground level is forced
over a mountain as a result of prevailing winds. (2 marks total)
Calculate the height of the resulting clouds. (1 mark)
ANS Air cools at the DALR of 10 per 1,000m. From the psych chart the air hits the dew
point at 4C, therefore clouds form at 1,000m of altitude.
(ii) If the mountain is 1,500 m in altitude, will there be snow or rain at the top? Explain
your answer and state any assumptions that you make. (1 mark)
ANS Assuming a saturated adiabatic lapse rate of 6C per 1,000m, over the next 500m it
CIV300TerrestrialEnergySystems,2016F
Test2QuestionSheet
will cool a further 3C, therefore 1C at the top, therefore rain, not snow.
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