diff --git a/Analysis/plot_snapshot.py b/Analysis/plot_snapshot.py
index 2f68bc259d38f18b6d96ca275f01f960cd306abf..a59d46c78d798101cc0eafe095c27d45eb690561 100755
--- a/Analysis/plot_snapshot.py
+++ b/Analysis/plot_snapshot.py
@@ -28,18 +28,18 @@ import math
 import cartopy.crs as ccrs
 from os import path
 
-def snapshot(directory, k = None, *, dashed = False, light = False,
+def snapshot(shp_tr_dir, k = None, *, dashed = False, light = False,
              new_figure = False, src_crs = ccrs.PlateCarree(),
              projection = ccrs.PlateCarree(), window = None):
     """Plots extrema, outermost contours and max-speed contours.
 
-    directory: containing the three shapefiles.
+    shp_tr_dir: containing the three shapefiles.
     dashed: boolean."""
     
-    reader_extr = shapefile.Reader(path.join(directory, "extremum"))
-    reader_outer = shapefile.Reader(path.join(directory, "outermost_contour"))
+    reader_extr = shapefile.Reader(path.join(shp_tr_dir, "extremum"))
+    reader_outer = shapefile.Reader(path.join(shp_tr_dir, "outermost_contour"))
     k1 = reader_extr.record(0).date_index
-    fname = path.join(directory, "ishape_last.txt")
+    fname = path.join(shp_tr_dir, "ishape_last.txt")
 
     try:
         ishape_last = np.loadtxt(fname, dtype = int)
@@ -59,7 +59,8 @@ def snapshot(directory, k = None, *, dashed = False, light = False,
         ishape_first = ishape_last[k - k1 - 1] + 1
 
     try:
-        reader_m_s = shapefile.Reader(path.join(directory, "max_speed_contour"))
+        reader_m_s = shapefile.Reader(path.join(shp_tr_dir,
+                                                "max_speed_contour"))
     except shapefile.ShapefileException:
         print("Shapefile max_speed_contour not found. "
               "Max-speed contours will not be plotted.")
@@ -170,7 +171,7 @@ if __name__ == "__main__":
                         action = "store_true")
     parser.add_argument("-d", "--dashed", action = "store_true",
                         help = "dashed linestyle, useful for a second snapshot")
-    parser.add_argument("directory", help = "containing the three shapefiles")
+    parser.add_argument("shp_tr_dir", help = "containing the three shapefiles")
     args = parser.parse_args()
 
     if args.grid or args.velocity:
@@ -216,7 +217,7 @@ if __name__ == "__main__":
                              (grid_nml["nlat"] - 1) * 0.25, edgecolor="black",
                              fill=False)
     ax.add_patch(rect)
-    snapshot(args.directory, args.k, dashed = args.dashed,
+    snapshot(args.shp_tr_dir, args.k, dashed = args.dashed,
              light = args.light, window = args.window)
 
     if args.velocity: