diff --git a/modules/util/util.py b/modules/util/util.py
index c132ebc66ca1a4f2c0db05bdcdf1434a047f3ba3..2ce16c6ceeb10f78346447ac5655421f0fe342f8 100644
--- a/modules/util/util.py
+++ b/modules/util/util.py
@@ -153,11 +153,11 @@ def value_to_index(nda, value):
     return idx
 
 
-# array solzen must be degrees, missing values must NaN
-def is_night(solzen, threshold):
+# array solzen must be degrees, missing values must NaN. For small 50x50km regions only
+def is_night(solzen, test_angle=80.0, threshold=0.10):
     solzen = solzen.flatten()
     solzen = solzen[np.invert(np.isnan(solzen))]
-    if np.max(solzen) > threshold:
+    if (np.sum(solzen > test_angle) / len(solzen)) > threshold:
         return True
     else:
         return False