def thetaEchange(Tguess, thetaE0, press):
"""
thetaEchange(Tguess, thetaE0, press)
Evaluates the equation and passes it back to brenth.
Parameters
- - - - - -
Tguess : float
Trial temperature value (K).
ws0 : float
Initial saturated mixing ratio (kg/kg).
press : float
Pressure (Pa).
Returns
- - - -
theDiff : float
The difference between the values of 'thetaEguess' and
'thetaE0'. This difference is then compared to the tolerance
allowed by brenth.
"""
thetaEguess = thetaes(Tguess, press);
#{'in change: ',Tguess,press,thetaEguess,thetaE0}
#when this result is small enough we're done
theDiff = thetaEguess - thetaE0;
return theDiff
def convecSkew(figNum):
"""
Usage: convecSkew(figNum)
Input: figNum = integer
Takes any integer, creates figure(figNum), and plots a
skewT logp thermodiagram.
Output: skew=30.
"""
c = constants();
plt.figure(figNum);
plt.clf();
yplot = range(1000,190,-10)
xplot = range(-300,-139)
pvals = np.size(yplot)
tvals = np.size(xplot)
temp = np.zeros([pvals, tvals]);
theTheta = np.zeros([pvals, tvals]);
ws = np.zeros([pvals, tvals]);
theThetae = np.zeros([pvals, tvals]);
skew = 30; #skewness factor (deg C)
# lay down a reference grid that labels xplot,yplot points
# in the new (skewT-lnP) coordinate system .
# Each value of the temp matrix holds the actual (data)
# temperature label (in deg C) of the xplot, yplot coordinate.
# pairs. The transformation is given by W&H 3.56, p. 78. Note
# that there is a sign difference, because rather than
# taking y= -log(P) like W&H, I take y= +log(P) and
# then reverse the y axis
for i in yplot:
for j in xplot:
# Note that we don't have to transform the y
# coordinate, as it is still pressure.
iInd = yplot.index(i)
jInd = xplot.index(j)
temp[iInd, jInd] = convertSkewToTemp(j, i, skew);
Tk = c.Tc + temp[iInd, jInd];
pressPa = i * 100.;
theTheta[iInd, jInd] = theta(Tk, pressPa);
ws[iInd, jInd] = wsat(Tk, pressPa);
theThetae[iInd, jInd] = thetaes(Tk, pressPa);
#
# Contour the temperature matrix.
#
# First, make sure that all plotted lines are solid.
mpl.rcParams['contour.negative_linestyle'] = 'solid'
tempLabels = range(-40, 50, 10);
output1 = plt.contour(xplot, yplot, temp, tempLabels, \
colors='k')
#
# Customize the plot
#
plt.setp(plt.gca(), yscale='log')
locs = np.array(range(100, 1100, 100))
labels = locs
plt.yticks(locs, labels) # Conventionally labels semilog graph.
plt.setp(plt.gca(), ybound=(200, 1000))
plt.setp(plt.getp(plt.gca(), 'xticklabels'), fontweight='bold')
plt.setp(plt.getp(plt.gca(),'yticklabels'), fontweight='bold')
plt.grid(True)
plt.setp(plt.gca().get_xgridlines(), visible=False)
plt.hold(True);
thetaLabels = range(200, 380, 10);
output2 = plt.contour(xplot, yplot, theTheta, thetaLabels, \
colors='b');
wsLabels = range(6, 24, 2);
output3 = plt.contour(xplot, yplot, (ws * 1.e3), wsLabels, \
colors='g');
thetaeLabels = range(250, 380, 10);
output4 = plt.contour(xplot, yplot, theThetae, thetaeLabels, \
colors='r');
# Transform the temperature,dewpoint from data coords to
# plotting coords.
plt.title('skew T - lnp chart');
plt.ylabel('pressure (hPa)');
plt.xlabel('temperature (deg C)');
#
# Crop image to a more usable size
#
TempTickLabels = range(5, 35, 5);
TempTickCoords = TempTickLabels;
skewTickCoords = convertTempToSkew(TempTickCoords, 1.e3, skew);
plt.xticks(skewTickCoords, TempTickLabels)
skewLimits = convertTempToSkew([5, 30], 1.e3, skew);
plt.axis([skewLimits[0], skewLimits[1], 600, 1.e3]);
#
# Create line labels
#
fntsz = 9 # Handle for 'fontsize' of the line label.
ovrlp = 1 # Handle for 'inline'. Any integer other than 0
# creates a white space around the label.
plt.clabel(output1, inline=ovrlp, fmt='%1d', fontsize=fntsz);
plt.clabel(output2, inline=ovrlp, fmt='%1d', fontsize=fntsz);
plt.clabel(output3, inline=ovrlp, fmt='%1d', fontsize=fntsz);
plt.clabel(output4, inline=ovrlp, fmt='%1d', fontsize=fntsz);
#
# Flip the y axis
#
plt.setp(plt.gca(), ylim=plt.gca().get_ylim()[::-1])
return skew
