def findLCL0(wv, press0, temp0):
"""
findLCL0(wv, press0, temp0)
Finds the temperature and pressure at the lifting condensation
level (LCL) of an air parcel (using a rootfinder).
Parameters
- - - - - -
wv : float
Mixing ratio (K).
temp0 : float
Temperature (K).
press0: float
pressure (Pa)
Returns
- - - - -
plcl : float
Pressure at the LCL (Pa).
Tlcl : float
Temperature at the LCL (K).
Raises
- - - -
NameError
If the air is saturated at a given wv, temp0 and press0 (i.e. Tdew(wv, press0) >= temp0)
Tests
- - - - -
>>> Td = Tdfind(5., 9.e4)
>>> Td > 280.
True
>>> findLCL0(5., 9.e4, 280.)
Traceback (most recent call last):
...
NameError: parcel is saturated at this pressure
>>> p1, T1 = findLCL0(0.001, 9.e4, 280.)
>>> print T1, p1
250.226034799 60692.0428535
"""
Td = Tdfind(wv, press0)
if (Td >= temp0):
raise NameError('parcel is saturated at this pressure')
theta0 = theta(temp0, press0, wv)
#evalzero = lambda pguess: lclzero(pguess, wv, theta0)
#will return plcl, Tlcl when Tchange returns approx. 0
#(i.e. when the parcel temperature = Td)
plcl = fzero(Tchange, [1000*100, 200*100], (wv, theta0))
Tlcl = invtheta(theta0, plcl, wv)
return plcl, Tlcl
def findLCL0(wv, press0, temp0):
"""
findLCL0(wv, press0, temp0)
Finds the temperature and pressure at the lifting condensation
level (LCL) of an air parcel (using a rootfinder).
Parameters
- - - - - -
wv : float
Mixing ratio (K).
temp0 : float
Temperature (K).
press0: float
pressure (Pa)
Returns
- - - - -
plcl : float
Pressure at the LCL (Pa).
Tlcl : float
Temperature at the LCL (K).
Raises
- - - -
NameError
If the air is saturated at a given wv, temp0 and press0 (i.e. Tdew(wv, press0) >= temp0)
Tests
- - - - -
>>> Td = Tdfind(5., 9.e4)
>>> Td > 280.
True
>>> findLCL0(5., 9.e4, 280.)
Traceback (most recent call last):
...
NameError: parcel is saturated at this pressure
>>> p1, T1 = findLCL0(0.001, 9.e4, 280.)
>>> print T1, p1
250.226034799 60692.0428535
"""
Td = Tdfind(wv, press0)
if (Td >= temp0):
#raise NameError('parcel is saturated at this pressure')
return press0, temp0
theta0 = theta(temp0, press0, wv)
#evalzero = lambda pguess: lclzero(pguess, wv, theta0)
#will return plcl, Tlcl when Tchange returns approx. 0
#(i.e. when the parcel temperature = Td)
plcl = fzero(Tchange, [1000 * 100, 200 * 100], (wv, theta0))
Tlcl = invtheta(theta0, plcl, wv)
return plcl, Tlcl
def Tchange(pguess, wv0, theta0):
"""
Returns the result of the equation T - Td.
Parameters
- - - - - -
pguess: float, a guess at the pressure at the LCL (input via fzero) (Pa)
wv0: float, mixing ratio of the parcel (kg/kg)
theta0: float, potential temperature of the parcel
Returns
- - - - - -
T - Td: float, T is the temperature on the theta0 dry adiabat,
and Td is the dewpoint temperature of a parcelat mixing ratio wv0 and pressure pguess.
"""
T = invtheta(theta0, pguess, wv0)
Td = Tdfind(wv0, pguess)
return T - Td
def Tchange(pguess, wv0, theta0):
"""
Returns the result of the equation T - Td.
Parameters
- - - - - -
pguess: float, a guess at the pressure at the LCL (input via fzero) (Pa)
wv0: float, mixing ratio of the parcel (kg/kg)
theta0: float, potential temperature of the parcel
Returns
- - - - - -
T - Td: float, T is the temperature on the theta0 dry adiabat,
and Td is the dewpoint temperature of a parcelat mixing ratio wv0 and pressure pguess.
"""
T = invtheta(theta0, pguess, wv0)
Td = Tdfind(wv0, pguess)
return T - Td
