Download lab10

ATS 351, Spring 2010
Lab #10
Winds, Fronts, and Cyclogenesis - 60 points
Please show your work for calculations.
Question #1: Pressure
(5 points) Using the ideal gas law, please calculate what is referred to as the “standard” sea level
pressure of the Earth. Values needed: average global temperature = 288K (15C); constant (R) =
287 J/kg/K; average sea level air density = 1.226 kg/m3. Please give pressure in millibars (what
you calculate will be in Pascals).
Question #2: Coriolis Force
(10 points) The equation for the Coriolis Force is:
Coriolis = 2 Ω sin (φ)
where Ω = the Earth’s angular rate of spin, 7.27x10-5 s-1
and φ = latitude in radians (To convert from degrees to radians, simply multiply your
degree by П and then divide by 180...and make sure your calculator mode is set to radians!)
Using the equation above, calculate the magnitude of the Coriolis force at:
a) the Equator
b) the North Pole
c) Fort Collins (latitude ~ 40°)
Using you answers, please explain how the Coriolis Force changes with latitude.
Question #3: Drawing Forces using Vectors
a) (5 points) Assuming geostrophic and frictionless flow, please draw vectors for the pressure
gradient and coriolis forces for the Northern Hemisphere.
L
1000 mb
1004 mb
H
1008 mb
b) (10 points) Given the pictures below of low and high pressure, please draw the direction of
the flow and the force vectors associated with areas of low and high pressure. Please give a
brief discussion on your picture. (Hint: you will only be utilizing 3 out of the 4 forces at this
point)
L
H
Question #4: Pressure Gradient Force and Wind Movement
A sea-level pressure is shown below where isobars are drawn every 4mb (Northern Hemisphere).
Answer the following questions.
a) (2 pts) Place a dashed line through the ridge and a solid line through the trough.
b) (2 pts) What would be the wind direction at point A and at point B?
c) (5 pts) Where would the stronger wind be blowing, at point A or B? Explain.
d) (4 pts) Compute the pressure gradient between points 1 and 2 and between points 3 and 4.
Question #5: Mid-latitude Cyclones
(10 points) Describe the process of how a mid-latitude cyclone develops, becomes mature, and then
becomes occluded (drawing pictures will help explain). During which stage the storm system is most
intense? What makes the storm system die? How long do these systems usually last?
Question #6: Fronts
(7 points) Use the SLP map shown below to answer the following questions about the pictured midlatitude cyclone.
a) Using the isobar analysis (red lines, mb), does the center of the above cyclone have a
relatively high or low-pressure center compared to the surrounding environment?
b) A cold front is the boundary between the cold, dry cP air and warm, moist mT air. There is
also usually a clear wind shift (change in wind direction) and a significant (~ 10°F) temperature
change at this boundary. Label the cold front on the above map using the appropriate symbol.
c) A warm front is the boundary between the warm, moist mT air and the cooler, moist mP air.
There is usually a slight wind shift at this boundary as well. Label the warm front on the
above map using the appropriate symbol.