1) At which level of the atmosphere is the Relative Humidity the highest? A) A C) C E) E G) G B) B D) D F) F H) H
Solution to Question #1
C - The right hand trace is the temperature profile, the left hand trace is the dewpoint profile. As we learned in the February 9 lecture, the closer the dewpoint is to the temperature, the more moist the air is. We can see that at Level C, the dewpoint profile is as close to the temperature profile as it ever gets in the sounding.
2) In which layer of the atmosphere would you expect the least upward vertical motion? A) Surface-A C) B-C E) E-F B) A-B D) C-D
Solution to Question #2
B - The more positive the slope of the temperature-elevation (lapse rate) plot, the more stable the atmosphere. Layer A-B has the most positive slope of all the choices. The more unstable the atmosphere is, the more likely there will be vertic al motion.
3) The most likely reason for the __________ that begins at level F would be the __________. A) Dewpoint, Thermosphere D) Thickness, lapse rate B) Lifting Condensation Level, Humidity E) Inversion, Ozone Layer C) Vorticity, Presence of wind shear
Solution to Question #3
E - An inversion is an increase in temperature with increasing elevation. This is clearly the case beginning at level F. Level F most likely denotes the beginning of the stratosphere. The Ozone Layer resides in the stratosphere and absorbs ul traviolet radiation from the sun, thus warming this layer and creating an inversion.
4) What type of precipitation do you suspect would be occurring in the above situation? A) Rain C) Sleet E) A or C G) B or D B) Snow D) Freezing Rain F) B or C H) C or D
Solution to Question #4
H - As we learned in the February 11 lecture, sleet and freezing rain occur in inversion situations when the temperature at the surface is below 32 F and the temperature aloft is above 32 F. Precipitation starts as snow, falls through a warmer layer in the inversion and melts into rain, then falls back into sub-freezing temperatures near the surface and freezes into either sleet or freezing rain (glaze). Depending on how thick the layer of c old air is, the precipitation will either freeze on contact (glaze) or completely freeze (sleet). Since this layer seems relatively deep, I accepted either choice H or choice C here although H is clearly the best choice.
5) Which of the following best describes a Z-R relationship? A) Correlates rainfall rate to radar return signal B) Measurement of atmospheric instability C) Calibration coefficient for rain gauges D) Defines how large hail will grow given a certain rainfall rate E) Coefficient used to determine ascent rate when launching a pibal F) Determines correction factor for adjusting pressure to sea level
Solution to Question #5
A - Z represents radar reflectivity which is a radar return signal and R represents a rainfall rate. The Z-R relationship strives to draw a comparison between the intensity of a radar signal returned by a precipitation area and th e rate of precipitation in the area.
6) The chart that Sir Francis Beaufort developed in 1806 can be most closely compared to: A) A Skew-T diagram D) The Safir-Simpson Scale B) A pilot balloon chart E) A radiosonde sounding C) The periodic table of the elements F) The Z-R scale
Solution to Question #6
D - The Beaufort Scale, as we learned in the February 16 lecture, ranks wind speeds according to their observed visual effects on land or sea. The Safir-Simpson Scale that we discussed in class ranks stron g hurricane force winds. This was clearly the best choice as the other 5 had nothing to do with ranking wind speeds.
7) An architect determines that a wind with a minimum force factor of 36
will blow over a wall she has designed. Based on her scale, a
wind of 3 knots has a force factor of 1. What is the minimum
wind speed (in knots) that will topple her wall?
A) 1 C) 9 E) 16 G) 20
B) 4 D) 12 F) 18 F) 25
Solution to Question #7
F - This presented a bit of a mathematical challenge. We learned in lecture that the force of the wind is proportional to the density of the air as well as the velocity squared of the wind. The solution to this problem looks like this:
8) Refer to the pressure analysis map of Pennsylvania below. In which state would you expect to find a low pressure center?
A) Ohio C) Maryland E) New Jersey B) West Virginia D) Delaware F) New York
Solution to Question #8
F - Remember, when reading pressure on a station model analysis, pressure is expressed to the nearest tenth and only the last 3 digits are shown with the decimal point omitted. So a pressure of 981 would be 998.1 mb and a pressure of 034 would be 1003.4 mb. If we draw a few isobars, we can see that pressure decreases toward the north and our best choice would be to place a low pressure area in New York somewhere.
9) On a weather analysis map, what is the standard interval for isobar lines? A) 5 F C) 4 inches Mercury E) 14.7 psi B) 5 C D) 4 millibars F) 1013.25 millibars
Solution to Question #9
D - This question was straightforward and should have been a freebie.
10) Which of the following cities is likely experiencing the strongest winds? A) Brownsville C) Junction E) Corpus Christi B) Abilene D) Lubbock F) Laredo
Solution to Question #10
D - The stronger the pressure gradient, the faster the winds will blow. When diagnosing pressure gradient, the closeness of the isobars is what is investigated. Lubbock is in the region of the strongest pressure gradient and will therefore lik ely be experiencing the strongest wind.
11) Which of the following would best characterize what is taking place over Texas according to the information provided by this map? A) Cold advection D) Negative vorticity advection B) Warm advection E) Dry advection C) Positive vorticity advection F) Moist advection
Solution to Question #11
A - Wind will blow somewhat parallel to the isobars with higher pressure on the right. Therefore, it should be easy to see that colder air will be transported (advected) by the wind across Texas from west to east.
12) Over a region, there is an east-west temperature gradient of 10 C/100 km at the surface with temperatures increasing toward the east. At the 850 mb level, there is a north south temperature gradient of 8 C / 100 km with temperatures increasing toward the south. A station in the region reports a surface wind of 10 knots at 315 while radiosonde data show winds of 30 knots at 135 at the 850 mb level. What can you say with the most confidence is happening to the atmospheric stability of the troposphere over this station? A) Troposphere is becoming more stable B) Troposphere is becoming less stable C) Troposphere will become neutral D) Lapse rate will become dry adiabatic
Solution to Question #12
A - The lower atmosphere will be cooling while the 850 mb level will be warming. A more stable lapse rate will develop.
13) City A and City B both are at latitudes of 45 degrees N. City A is
2,000 miles west of City B. If a missile is to be launched from
City B at City A, which direction should the missile be initially
directed at to successfully impact with City A?
A) North D) Southwest G) East
B) Northwest E) South H) Northeast
C) West F) Southeast
Solution to Question #13
D - The Coriolis Force in the northern hemisphere will act to the right of the direction of motion of an object or parcel so if the missile is launched to the southwest, the Coriolis Force will tend to accelerate it northward such that the missile will have a change to strike City A.
14) An object rotates 30 times in one minue. What is its angular velocity in radians per second? A) 60 * cos 30 C) 2*pi E) pi B) 30 * sin 30 D) 15*pi F) pi squared
Solution to Question #14
E - Each time the object makes one rotation, it is traveling through an angular distance of 2*pi radians. In one minute, the object makes 30 rotations which would be 30 * 2 * pi radians = 60 * pi radians. In one minute there are 60 seconds so 60 * pi / 60 = pi radians / second.
15) The length of a day on planet Y is 144 hours. What would be the ratio
of the Coriolis Force acting on a 25 mph wind on Earth at 45
degrees N latitude to the Coriolis Force acting on a 5 mph wind at
45 degrees N latitude on planet Y?
A) 30:1 C) 5:1 E) 1:30 G) 1:5
B) 6:1 D) 125:1 F) 1:6 H) 125:1
Solution to Question #15
A - The Coriolis Force acting on a wind is defined by 2 * omega * sin latitude * velocity, where omega is the angular speed of the planet. On planet Y, omega will be 6 times slower or less than Earth as 144/24 = 6. Therefore, the Coriolis Force will be 6 times less due to the slower rotation. Also, the wind speed considered is 5 times less on planet Y, so the Coriolis Force will be 5 times less due to the slower wind speed under consideration. 6 * 5 = 30 so the wind under consi deration will be under the influence of a Coriolis Force 30 times greater on Earth, so the answer is 30:1.
16) In the Geostrophic approximation, the __________ force is equal to the __________ force. A) Gravitational, Pressure gradient E) Pressure gradient, Coriolis B) Coriolis, Gravitational F) Gravitational, Frictional C) Centrifugal, Pressure gradient G) Hydrostatic, Coriolis D) Frictional, Centrifugal
Solution to Question #16
E - In the mid-latitudes, this approximation is often suitable when talking about motions on the large scale. This topic was covered in the February 18 lecture.
17) Consider the map of Kansas below. Wind V is a geostrophic wind.
Which city do you suspect is closest to a high pressure center? A) Scott City C) Harrisonville B) Mankato D) Harper
Solution to Question #17
C - In the geostrophic approximation, the pressure gradient force will balance the Coriolis Force and high pressure will be to the right of the direction of flow.
18) What is true about a parcel suspended in a fluid that is in hydrostatic balance? A) It is undergoing shearing in the vertical and horizontal directions B) Its temperature is equal at all points in the parcel C) The coriolis force on the parcel acts equal and opposite to the force of gravity D) The parcel is under the influence of a high pressure system F) The pressure gradient force acting upwards equals the gravity force acting downward G) The moisture in the parcel will eventually condense onto cloud condensation nuclei
Solution to Question #18
F - Visit the February 20 lecture for a full explanation of hydrostatic balance.
19) On a day in Tallahassee, you observe with your aerovane a 5 knot wind
at 225 degrees. A few hours later, you observe a 15 knot wind at
135 degrees. A few hours after that, you observe a 17 knot wind at
315. A __________ pressure system has likely passed to your
__________.
A) Low, South E) High, South
B) Low, North F) High, North
C) Low, East G) High, East
D) Low, West H) High, West
Solution to Question #19
A - This is a good thought question. As the low approaches, the winds will shift from a southwest to southeast to northwesterly direction as the low passes to the south. See the February 23 lecture to rev iew how to find the wind direction from the wind direction expressed in angular form.
20) A weather balloon has made the following temperature measurements:
| Pressure level (mb) | Temperature (Kelvin) |
|---|---|
| 1000 (surface) | 298 |
| 850 | 282 |
| 700 | 267 |
| 600 | 258 |
| 500 | 244 |
Which is closest to the vertical distance between the surface and the 500 mb level? (Hints: ln (1000/500) = .693; g=9.81; R=287) A) 5520 m C) 5350 m E) 5120 m B) 5400 m D) 5480 m F) Cannot determine
Solution to Question #20
D - We learned in the February 21 lecture about the hypsometric equation. This lets us calculate the vertical distance between two pressure levels. The equation is expressed as Z = R * T (average) / g * ln (p(bottom) / p(top)). In other words, the vertical distance is equal to the Gas Constant (the same one used in the Ideal Gas Law) times the average temperature in the layer being considered (in this case, the surface to 500 mb) times the natural logarithm of the bottom pressure (1000 mb) divided by the top pressure (500 mb) all divided by the gravitational constant (9.81). I give you everything you need. All you really needed to know was the hypsometric equation and you had to realize that you needed to find the average temperature in the layer. So you needed to add up all the temperatures at each pressure level, and divide by 5. At the end, you'd come up with a value pretty close to 5480 meters.
21) Consider the map of New York State below showing isoplethes of 1000-500 mb thicknesses (in meters):
If you were a weather forecaster, between which two cities would your forecasted rain-snow line pass? A) Ithaca-Elmira D) Syracuse-Ithaca B) Buffalo-Rochester E) Albany-Plattsburgh C) Jamestown-Rochester F) Binghamton-Albany
Solution to Question #21
D - In class on February 21, we learned that the a 1000-500 mb thickness (that is the vertical distance between a pressure of 1000 mb and the level in the atmosphere where the pressure is 500 mb) of 5400 me ters is often approximated as the rain-snow cutoff line in weather forecasting. The only choice possible based on the map would be D.
22) At which of the above stations if the relative humidity the highest? A) A C) C B) B D) D
Solution to Question #22
D - The closer the dewpoint temperature is to the temperature, the higher the relative humidity. Choice D shows a dewpoint depression of only 1 degree versus higher values at all the other stations.
23) Station F is located 50 miles east of Station D and is experiencing a 15 knot wind at 270 degrees. What do you suppose is occurring at Station E which is midway between Stations D & F based on the information available? A) Positive vorticity B) Negative vorticity C) Warm advection D) Cold advection E) Surface divergence F) Surface convergence
Solution to Question #23
E - A 270 degree wind would be coming out of the west. Since Station D is experiencing an easterly wind, we can intuitively get the sense that the air must be spreading apart somewhere between Station D & F. E is the best choice here.
24) Weather stations A, B, C, D, and E are lined up from west to east respectively. Station A is reporting a wind speed of 25 knots and the wind speeds decrease at each station from west to east by increments of 5 knots per station. All stations are reporting a wind direction of 180 degrees. Based on the provided information, what can you say with the most confidence is occurring at Station C? A) Warm advection E) Cyclonic flow B) Cold advection F) Anticyclonic flow C) Negative vorticity advection G) Geostrophic flow D) Positive vorticity advection H) Hydrostatic flow
Solution to Question #24
F - Consider the diagram below to aid in your understanding of this problem.
25) Snowy Haven is a village at the eastern end of a rectangle-shaped lake that is 100 miles east-west and 30 miles north-south. A wind from __________ will provide the best __________ for Lake Effect Snow. A) 0 degrees, Moisture E) 0 degrees, Vertical motion B) 90 degrees, Vorticity F) 90 degrees, Fetch C) 180 degrees, Vertical motion G) 180 degrees, Moisture D) 270 degrees, Fetch H) 270 degrees, Vorticity
Solution to Question #25
D - Fetch is defined as the distance that the wind travels over the lake. The village is at the east end of the lake and the lake's long axis is aligned in the east-west direction. Therefore, the best fetch would be a wind blowing in the east- west direction as it would have the most time to pick up moisture from the lake. The village would be downwind a fetch coming from 270 degrees, which is the westerly direction.
BONUS - 2 points
In the February 11 lecture on the Class Web Site, there is a picture from a popular album cover from the late 1980s. Name the band ________________________________________ (1 point) Name the album ________________________________________ (1 point)
The above picture is from Pink Floyd's 1989 live album Delicate Sound of Thunder.
ESSAY QUESTION (25 points)
1) Fully explain a Skew-T diagram. Go into as much detail as possible. Diagrams may be helpful.
Skew-T diagrams are discussed in the February 9 lecture.
2) Derive the hydrostatic equation using the approach we developed in class.
The hydrostatic equation is derived in full in the February 21 lecture.
3) Draw a weather map with at least 10 station models. Draw isobars and isotherms. Plot as much information on your station models as possible. Set up your map in such a way that you have an area of warm advection, cold advection, an area of convergence, and an area of divergence. Explain where and why each is occurring.
This question allowed you to get creative, especially if you have some artistic talent.
4) Explain the Sea Breeze phenomena as completely as possible. Discuss how the Sea Breeze behaves at different times of the day. Incorporate monsoons into your discussion.
The Sea Breeze phenomena along with monsoons were discussed in lecture on February 27.
5) Describe the relationship between vorticity and vertical motion as completely as possible.
Vorticity and its relationship to vertical motion were discussed in the February 25 lecture.