Atms 111 Individual Exam#02

Name:______29 November 2017

ATMS 111 INDIVIDUAL EXAM#02

Choose the single best answer in Questions (1) – (15), each question is worth four points. Questions (16) - (18) together are worth 40 points. EXAM#02 is worth 100 total points.

------

An expression relating fish metabolism (dependent or “y” variable, units of Joules per second [J s-1]) to lake temperature (independent or “x” variable, units of degrees Celsius [oC]) is defined as

y = Bx + C

where “B” and “C” are constants that can be determined from the following observations; {a} fish metabolism was measured to be 10.0 J s-1 at a lake temperature of 30oC and {b} fish metabolism was measured to be 1.0 J s-1 at a lake temperature of 0oC.

Use this information to help answer Questions (1) - (3).

(1) Constant “B” has the value ______[J s-1] / [oC].

(a) 0.1

(b) 0.2

(d) 0.4

(2) Constant “C” has the value ______[J s-1].

(a) 0.0

(b) 1.0, PE#4, Q(1)

(d) 3.0

(3) A measured lake temperature of 20oC would likely indicate a fish metabolism of ______[J s-1].

(a) 7.0, PE#4, Q(1)

(b) 8.0

(d) 10.0

(4) A tipping bucket gauge registers a tip on June 18 at 18.90000 fractional day (FD). This corresponds to the decimal military time (DMT) on June 18 of ______.

(a) 20.0

(b) 20.7

(d) 21.6, PE#4, Q(5)

(5) The gauge registers another tip at 21.8 DMT on June 18, showing an accumulation of 1.0 mm between this time and the DMT tip time in Problem (4). Calculate the rain rate [mm per hour] at the tipping bucket rain gauge over the period between the two tips. {Please show your work for complete credit.}1.0 mm/(21.8-21.6 h) = 5 mm h-1, PE#4, Q(6)

Name:______29 November 2017

ATMS 111 INDIVIDUAL EXAM#02

(6) Assuming a flat earth and a straight radiation beam from a WSR88D station, a radiation beam for an elevation angle of 0.5o above the horizon at a horizontal distance of 100 kilometers from the radar station will be found ______kilometers above the ground. Assume that the radar dome is sitting on the ground.

(a) 0.5236

(b) 0.8727, PE#4, Q(8)

(d) 1.3963

(7) What might cause a problem with using the lowest radar scan data from the Greer, SC WSR88D radar to estimate rainfall for locations in Haywood County?

{a} scan over the tops of clouds à missing precip –OR- {b} beam blocking due to the mountains, LR#4, EQ(c)

(8) Hiking up Mt. LeConte you measure air pressure of 925 hPa at 825 meters and 850 hPa at 1555 meters. The scale height at Mt. LeConte on the day of your hike is ______meters.

(a) 7844

(b) 7933

(d) 8633, PE#5, Q(1)

(9) On the day of the hike in Problem (8), the estimated air pressure at the top of Mt. LeConte (altitude 2010 meters) would be ______hPa.

(a) 806, PE#5, Q(2)

(b) 816

(d) 836

(10) Describe if the air pressure estimate in Problem (9) involves an interpolation or an extrapolation given the measurements made in Problem (8).

Measurements were made at Z=825 and 1555 meters, the top of Mt. LeConte is outside of the range of measurements and so the estimate is an extrapolation

(11) If colder air moves over Mt. LeConte on Day 2 than on the day of the hike in Problem (8), one would expect that the scale height on Day 2 between 825 and 1555 meters would be ______on the day of the hike and that the pressure at the top of Mt. LeConte on Day 2 would be ______on the day of the hike.

(a) greater than, greater than

(b) greater than, less than

(d) less than, less than, PE#5, Q(3)

Name:______29 November 2017

ATMS 111 INDIVIDUAL EXAM#02

We travel from Station A (elevation=2200 feet or 670.7 meters) where we measure a surface temperature of 18oC and a surface air pressure of 950 hPa. We travel 100 km to the east (compass heading 90o) and measure a surface air pressure of 993 hPa at Station B (elevation = 900 feet or 274.4 meters). Find the illustration at Problem (17) on Page 5. The stations are located in the Northern Hemisphere.

(12) A measured air temperature of 18oC at an elevation of 670.7 meters corresponds to a “below ground” air temperature of ______oC at an elevation of 274.4 meters at Station A, assuming an environmental lapse rate of 6.5oC/ km.

(a) 13.4

(b) 15.6

(d) 20.6, PE#6, Q(1A)

(13) The layer average air temperature between 274.4 and 670.7 meters at Station A is ______Kelvin.

(a) 288.7

(b) 289.8

(d) 292.3, PE#6, Q(1B)

(14) The calculated scale height using Eq. (6.2) between 274.4 and 670.7 meters at Station A is ______meters.

(a) 459

(b) 532

(d) 8651

(15) Reducing the surface air pressure measured at Station A to 900 feet elevation using Eq. (6.3) results in an estimated air pressure of ______hPa.

(a) 985.1

(b) 995.1, PE#6, Q(1D)

(d) 1015.1

(BONUS) The average air pressure at 900 feet elevation between Stations A and B is ______Pascals.

(a) 98905

(b) 99405, PE#6, Q(1E)

(d) 100405

Name:______29 November 2017

ATMS 111 INDIVIDUAL EXAM#02

(16) 15 points

Calculate the surface wind speed [m s-1] estimate between Station A and Station B given the conditions in Problems (12) – (15) using Eq. (6.4), being careful to use the proper units in the equation.

V = [(287 J K-1 kg-1)(292.3 K)/(99405 Pa)(8x10-5 s-1)] * (210 Pa)/(100x103m)

= 22.15 m s-1

Name:______29 November 2017

ATMS 111 INDIVIDUAL EXAM#02

(17) 15 points

Let us assume that the air pressure changes most rapidly from Station A to Station B in the horizontal on a direct line between Station A and Station B (see figure above) given the conditions in Problems (12) – (15). Determine the most likely wind direction between Station A and Station B given the calculated and measured air pressures at an elevation of 900 feet, assuming that the winds are geostrophic and that air flow is without the influence of friction. How would the wind direction change from this estimate if the influence of friction suddenly became important (explain how the numerical estimate of geostrophic wind direction would increase or decrease based on the influence of friction)?

995.1 hPa at Station A and 993 hPa at Station B at an elevation of 900 feet indicates that lower pressure is toward Station B. Given the assumption that air pressure changes most rapidly from Station A to Station B in the horizontal on a direct line between Station A and Station B, the isobars are directed with a north-south orientation so that the (geostrophic) wind direction must be blowing from the north or from the south. Since low pressure is found toward Station B and we are in the Northern Hemisphere, the winds must be blowing so that low pressure is toward the left of the direction of the winds, hence, the winds must be blowing from the north (360o).

If friction becomes important, the winds change to being cross-isobar flow, blowing toward low pressure. The winds would shift ~30o so that the winds were blowing from the northwest (360o - 30o = 330o).

Name:______29 November 2017

ATMS 111 INDIVIDUAL EXAM#02

(17) 10 points

Weather station observations are plotted on the map below. The number to the upper right of the station circle is related to the sea level pressure (mb). Draw the 1012 mb isobar (with proper labeling) over the lower 48 states of the U.S. and write the words “HIGH” and “LOW” to indicate areas of high and low sea level pressure, respectively.

Name:______

Work to be included for Problem _____ of Exam _____ in class ATMS _____

Formula Sheet 1 for Exam#2 ATMS 111

H= -(z-zB)lnpz-ln[pzB] (6.0)

Tz= TzB- Γ*[z- zB] (6.1)

H= RTg (6.2)

pz= pzBexp-(z-zB)H (6.3)

V= RTpfΔpΔn= RTpf pS- pNΔn (6.4)

where the terms in Eq. (6.1) are air temperature at some altitude [oC], air temperature at some lower level [oC], environmental lapse rate (= 6.5 oC/ km), altitude [m], and altitude at some lower level [km]. The terms in Eq. (6.2) are scale height [m], dry air gas constant [= 287 J kg-1 K-1], layer average air temperature [K], and the acceleration due to gravity [= 9.81 m s-2]. Eq. (6.3) is identical to the pressure equation introduced in Preparatory and Laboratory Exercises #5. The terms in Eq. (6.4) are the wind speed [m s-1], dry air gas constant [= 287 J kg-1 K-1], layer average air temperature [K], average air pressure [Pascals] between a north and south location, Coriolis parameter [=8.0x10-5 s-1], air pressure difference [Pascals] between a north and south location, and horizontal distance between the north and south locations [meters].