--- ray/src/gen/gensky.c	1990/03/12 09:49:25	1.3
+++ ray/src/gen/gensky.c	1991/08/06 08:22:06	1.5
@@ -53,7 +53,7 @@ main(argc, argv)
 int  argc;
 char  *argv[];
 {
-	extern double  atof();
+	extern double  atof(), fabs();
 	int  i;
 
 	progname = argv[0];
@@ -102,6 +102,11 @@ char  *argv[];
 		else
 			userror("bad option");
 
+	if (fabs(s_meridian-s_longitude) > 30*PI/180)
+		fprintf(stderr,
+	"%s: warning: %.1f hours btwn. standard meridian and longitude\n",
+			progname, (s_longitude-s_meridian)*12/PI);
+
 	printhead(argc, argv);
 
 	computesky();
@@ -128,10 +133,10 @@ computesky()			/* compute sky parameters */
 	if (zenithbr <= 0.0)
 		if (cloudy) {
 			zenithbr = 8.6*sundir[2] + .123;
-			zenithbr *= 1000.0/683.0;
+			zenithbr *= 1000.0*.0064/3.;
 		} else {
 			zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38;
-			zenithbr *= 1000.0/683.0;
+			zenithbr *= 1000.0*.0064/3.;
 		}
 	if (zenithbr < 0.0)
 		zenithbr = 0.0;