diff --git a/modules/util/util.py b/modules/util/util.py
index d21fc755d7188de7ffe298c4f1517e9b97b1f234..fd405d33f12935abd782d79eb9c52df5d96c708e 100644
--- a/modules/util/util.py
+++ b/modules/util/util.py
@@ -161,3 +161,13 @@ def is_night(solzen, test_angle=80.0, threshold=0.10):
         return True
     else:
         return False
+
+
+# array solzen must be degrees, missing values must NaN. For small roughly 50x50km regions only
+def is_day(solzen, test_angle=75.0):
+    solzen = solzen.flatten()
+    solzen = solzen[np.invert(np.isnan(solzen))]
+    if len(solzen) == 0 or np.sum(solzen <= test_angle) < len(solzen):
+        return False
+    else:
+        return True