3H I~>F >A~
d
n ***** PSYCHROMETER *****
x8 A program for the Microbee to convert readings from
; a PSYCHROMETER to several common measures of humidity.
8 AN ESTIMATE OF THE HEIGHT AT WHICH CLOUDS WILL FORM
is also given.
:257,1
24,5:
" PSYCHROMETER ":
C \"A program to convert readings from a psychrometer to several"
"common measures of humidity. An estimate of the height of the "\"cloud base and temperature at this height is also calculated."
> 10,14:"Do you want instructions on a psychrometer (Y/N)?"
"' A1$=$:A1$=""A1$<>"Y"A1$<>"N"290
, A1$="Y"730
6
@' "Height above sea level in metres";
J H1
T$ "Dry-bulb temperature (deg C) ";
^ T0
h$ "Wet-bulb temperature (deg C) ";
r T1
|I T1>T01,15::"ERROR: Dry-bulb < wet-bulb temperature ";::20:660
) Convert celsius to absolute (Kelvin)
T3=T0+273.15
T4=T1+273.15
1 E1=(21.4-5351/T4): calculate vapour pressure
@ P0=1014-(H1/884)*100: If height in feet alter to 884 to 2900
> E0=E1-P0*(T3-T4)/1555: Adjust vapour pressure for altitude
5 D0=5351/(21.4-2.30258*(E0)): Calculate dew point
D0=D0-273.15
< E2=(21.4-5351/T3): Calculate saturation vapour pressure
- R0=100*E0/E2: Calculate relative humidity
8 Q0=.622*E0/(P0-.378*F0): Calculate specific humidity
" ANSWERS."
3 "Dew point = ";((D0*10+0.5))/10;" ";"C";". "
&4 "Vapour pressure = ";((E0*10+0.5))/10;" MB. "
0> "Saturation vapour pressure = ";((E2*10+0.5))/10;" MB. "
:0 "Relative humidity = ";(R0+0.5);" percent."
DH "Specific humidity = "((1000*Q0*10+0.5))/10;" parts per thousand."
N% 920: Calculate cloud base height
X8 \"Press any key to continue or 'Q' to quit ";:12
b A1$=$:A1$=""610
l A1$="Q"
v- 41,1:"Change to :- ";:C7$:C7$=""650
H1=(C7$)
' 35,1:H1;" "
+ 41,2:"Change to |-";:C7$:C7$=""680
T0=(C7$)
( 31,2: T0;" "
, 41,3:"Change to |-";: C7$:C7$=""710
T1=(C7$)
) 31,3:T1;" "
380
G :\"A psychrometer consists of two thermometers, one with a sleeve"
? "of wet fabric around the bulb. The 'wet bulb' thermometer"
@ "shows a reading which is lower than that of the 'dry bulb'"
: "thermometer which reads the ambient air temperature."
B \"The difference between the two temperatures is known as the"
> "'wet bulb depression' and is proportional to the rate of"
? "cooling of the wet bulb due to evaporation from its moist"
"surface."
* \"Pres any key to continue."
4 A1$=:A1$=""820
>
H \"A psychrometer can be made by mounting two matched thermometers"\"firmly (glue is preferable) to a thin wooden paddle with the"
R "bulbs projecting from one end. At the other end, drill a hole"\"and tie a stout piece of string to the paddle so that it can"
\ "be whirled rapidly. A layer of muslin is tied around one of the"\"bulbs and dipped in water. The psychrometer is then whirled"
fL "rapidly for about a minute, or until the temperatures do not"\"change."
p "Press any key to continue."
z A1$=:A1$=""890
# *** calculate cloud height ***
U0=0.01*R0
T5=T3/((U0)^(2/7))
> F0=2.30258*(T5/T3)+(2/7)*2.30258*(U0)+1548.06*(1/T5-1/T3)
G0=1/(T3*T5)-1548.06/(T5*T5)
T5=T5-F0/G0
T5<1T5=1
(F0/G0)>=0.01940
Z0=100*(T3-T5)
@ "Height of cloud base = ";(Z0);" metres above the surface."
K "Temperature at the cloud base = ";(((T5-273.15)*10+0.5))/10;" C. "
Wet bulb too low
A 1,15::" Error :- wet bulb temperature too low ";::22:660
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