Add a comment on cosH bounds

src/sun.c

@@ -55,8 +55,11 @@ static float calcSun(int year, int month, int day, float latitude,
                (cosDec * cos((M_PI / 180.0f) * latitude));
 
   if (cosH > 1) {
+    // the sun never rises at this location on the specified date
     return 0;
-  } else if (cosH < -1) {
+  }
+  if (cosH < -1) {
+    // the sun never sets at this location on the specified date
     return 0;
   }