Review of Basic Techniques
(Due Beginning of Class, Friday 10 September)
1. All labs are to be kept in a three hole binder. Turn in the binder when
you have finished the Lab.
2. Show all PROCEDURE. No credit given if only
answer is provided.
3. Unless otherwise noted, you may work together. But remember, YOU
are the one who will be responsible for understanding the material for
exams and when you are out in the profession. So STRIVE to
understand what you are doing. Don't let someone else do your
thinking for you.
1. Determine the value of a degree in km at 40oN latitude (trigonometry).
a = radius of earth = 6370 km
r = radial distance to the axis of rotation which,
by simple geometry, = a cos phi where phi is the latitude
Circumference = 2π R
Distance (km) of 1o = (Circumference)/360 o
For latitude R = a and a degree is (2π 6370 km )/360 o = 111.3 km
For longitude R = r and a degree is (2π 6370 km cos 40) = 85.3 km
2. (a) Give the PHYSICAL INTERPRETATION of each term of
equation (cartesian coordinate) below, where V is the three dimensional wind vector:
A B C
(b) Name each term in equation.
(c) Solve the equation for the local tendency.
(d) Expand term "C".
(e) Assume that dT/dt = 0 for the chart given and that there is no vertical motion. Determine the local temperature tendency at the station reporting the wind of 225o, 25 knots, shown in the diagram below. External grid points indicated by crosses are 100 km distant from station, nominally placed at center of implied x-y coordinate cross. Isotherms are north-south.
(a) A is the temperature change experienced by the moving parcel, as if a thermometer moved with the air parcel.. B is the temperature change measured at a location fixed with respect to the surface of the earth. C is the contribution to the local temperature change made by cold or warm advection.
u and v are the horizontal wind components, but there is no north/south
temperature gradient in this case. Hence,
where u = 25 knots (sin 45) = 17.68 knots = 32.5 km h-1
The temperature change will be entirely due to advection,
-1.6o C h-1
3. (a) Physically interpret the terms to the right of the equals sign in
equation (2) (basic calculus)
(b) Equations (3a,b) are the geostrophic wind components. Put (3a,b) into (2) to determine the divegence of the geostrophic wind. Assume g and f are constants. I realize we have not discussed divergence, or horizontal divergence. But this question involves you working with the mathematical operations, not the meteorological interpretation.
4. (a) Physically interpret the terms to the right of the equals sign in
equation (2) (basic calculus)
(b) Equations (3a,b) are the geostrophic wind components. Put (3a,b) into (2) to determine the divegence of the geostrophic wind. Assume g and f are constants.
(a) ∂u/∂x is the horizontal shear of the west wind along the x axis or
the variation of the west wind along the x axis or the variation of the west wind speed along the x axis.
∂v/∂y is the horizontal shear of the south wind along the y axis or
the variation of the south wind along the y axis or the variation of the south wind speed along the y axis.
Put Eq 2(a,b) into (1)
Equation (3b) states that the horizontal divergence of the geostrophic wind is related to the variation of north-south slope of an isobaric surface along the x-axis and to the variation of the west-east slope of an isobaric surface along the y-axis. However, the second derivatives are identical but opposite sign, so the horizontal divergence of the geostrophic wind
DIVh = 0 (4)
4. Obtain a plot of the NAM initialization of 500 mb heights and absolute vorticity AND surface pressure with 1000-500 mb thickness at initialization time for 12 UTC 31 August 2010.
(a) Write out the script you executed on the command line to obtain this.
(b) Append -p on the command line after the command to print a black and white copy to turn in with this lab.
5. (a) Use the script mod_grib -p to print out a copy of the 500 mb heights for 12 UTC 31 August 2010.
(b) Annotate troughs and ridges as we did in Metr 201 (and Metr 400).
6. For the sounding distributed (KOAX 12 UTC 31 August 2010), determine the
(a) LCL, LFC and CAPE and CIN areas for 12 UTC (first copy);
(b) CT, and CCL (second copy)
Make sure you draw everything neatly and use the correct color conventions.