10 REM PROGRAM D4_COND
50 DIM T0(41), T1(41)
60 C = 400: RHO = 4000: K = 5: SGMA = 5.67 * 10 ^ (-8): QMAX = 250
70 DZ = .05: OMGA = 7.27 * 10 ^ (-5): DT = .45 * C * RHO * DZ ^ 2 / K
80 C1 = .45: C2 = DT / (C * RHO * DZ): C3 = OMGA * DT: C4 = .9 * 290 ^ 4
RS = 4
DIM BSUN(200)
DIM R(14), G(14), B(14)
R(1) = 54: G(1) = 0: B(1) = 54
R(2) = 24: G(2) = 0: B(2) = 40
R(3) = 0: G(3) = 0: B(3) = 48
R(4) = 0: G(4) = 0: B(4) = 63
R(5) = 0: G(5) = 36: B(5) = 60
R(6) = 16: G(6) = 48: B(6) = 63
R(7) = 0: G(7) = 56: B(7) = 0
R(8) = 36: G(8) = 63: B(8) = 0
R(9) = 63: G(9) = 63: B(9) = 0
R(10) = 63: G(10) = 48: B(10) = 0
R(11) = 63: G(11) = 36: B(11) = 0
R(12) = 63: G(12) = 24: B(12) = 0
R(13) = 54: G(13) = 0: B(13) = 0
R(14) = 36: G(14) = 0: B(14) = 0

SCREEN 12
FOR I = 1 TO 14
HUE = 65536 * B(I) + 256 * G(I) + R(I)
PALETTE I, HUE
NEXT I
90 CLS
WINDOW (0, -40)-(640, 20)
CIRCLE (100, 0), RS, 12
PAINT (100, 0), 12
GET (100 - RS, -RS)-(100 + RS, RS), BSUN
PUT (100 - RS, -RS), BSUN
CLS
COLOR 11: LOCATE 23, 62: PRINT "DEPTH (cm)"
LINE (520, 1)-(520, -23)
FOR I = 0 TO 6
LINE (520, 1 - 4 * I)-(510, 1 - 4 * I)
LOCATE 10 + 2 * I, 66: PRINT 5 * I
NEXT I
LINE (120, 1)-(520, 2), 11, BF
LINE (120, 4.5)-(520, 5), 11, BF
COLOR 1: LOCATE 11, 12: PRINT "T (øC)"
FOR XI = 120 TO 520 STEP 80
LINE (XI, 2)-(XI, 1)
LOCATE 9, INT(XI / 8) - 1: PRINT XI / 16 - 12.5
NEXT XI

COLOR 11: LOCATE 19, 10: PRINT "AS DEPTH INCREASES"
LOCATE 20, 10: PRINT "TEMPERATURE VARIATIONS"
LOCATE 21, 10: PRINT "1. DECREASE IN MAGNITUDE"
LOCATE 22, 10: PRINT "2. ARE DELAYED "

REM ASSUMING SUN FOR 12 HOURS AND IR LOSS 24 HOURS
COLOR 9: LOCATE 5, 7: PRINT "DAY"
COLOR 13: LOCATE 2, 16: PRINT "TEMPERATURE VARIATIONS IN GROUND DUE TO CONDUCTION"
COLOR 7: LOCATE 6, 4: PRINT "HOUR =": COLOR 15
140 T1(40) = 300
150 FOR M = 0 TO 40
160 T0(M) = 300
170 NEXT M
HUESKY = 6
LINE (120, 5)-(520, 15), HUESKY, BF
180 FOR N = 1 TO 501
   IF N = 120 OR N = 360 THEN LINE (120, 5)-(520, 15), 4, BF: COLOR 1: LOCATE 5, 6: PRINT "NIGHT": COLOR 15
   IF N = 240 OR N = 480 THEN LINE (120, 5)-(520, 15), 6, BF: COLOR 9: LOCATE 5, 6: PRINT " DAY ": COLOR 15
190 QDAY = SIN(C3 * N): IF QDAY < 0 THEN QDAY = 0
   IF QDAY > 0 THEN
        PUT (240 + N MOD 240, 10 * SIN(C3 * N)), BSUN, XOR
        END IF
200 T1(0) = T0(0) + C2 * (QMAX * QDAY - SGMA * (T0(0) ^ 4 - C4))
FOR M = 0 TO 40
HUE = 7 + INT(7 * (T0(M) - 300) / 20)
CIRCLE (320 + 10 * (T0(M) - 300), -M), 2, HUE
PAINT (320 + 10 * (T0(M) - 300), -M), HUE
COLOR 7: LOCATE 6, 11: PRINT (CINT(N * DT / 3600) + 6) MOD 24: COLOR 15
NEXT M

TT = TIMER + .01
DO UNTIL TIMER > TT: LOOP

FOR M = 1 TO 39
T1(M) = T0(M) + C1 * (T0(M - 1) + T0(M + 1) - 2 * T0(M))
NEXT M
IF QDAY > 0 THEN
        PUT (240 + N MOD 240, 10 * SIN(C3 * N)), BSUN, XOR
        END IF
FOR M = 0 TO 40
IF N < 501 AND CINT(T1(M) * 16) <> CINT(T0(M) * 16) THEN
        PAINT (320 + 10 * (T0(M) - 300), -M), 0, 0
END IF
T0(M) = T1(M)
NEXT M

310 NEXT N