fix typos in tutorial 4

Author: zmaalick

notebooks/CSSP_20CRDS_Tutorials/tutorial_4_advance_analysis.ipynb

@@ -529,14 +529,13 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "# Now extract present day\n",
     "# extract a single cube of maximum air_temperature at 1.5m cube from the cubelist\n",
     "max_temp = cubelist.extract_strict('air_temperature' & iris.AttributeConstraint(Height='1.5 m') &\n",
     "                           max_temp_cons)\n",
     "# extract data for the the Shanghai region using extract_rot_cube() function\n",
     "max_temp = extract_rot_cube(max_temp, min_lat, min_lon, max_lat, max_lon)\n",
     "\n",
-    "\n",
+    "# Now extract present day\n",
     "start_time = 1981\n",
     "end_time = 2010\n",
     "\n",
@@ -548,7 +547,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Now we need to calculate the number of warm days, we do so by counting all the data points that are greater than 90th percentile of the baseline period within the last 30 years. We can use numpy method **np.where** which return 1 where max_temp is greater then max_temp_pc90 and returns 0 otherise. \n",
+    "Now we need to calculate the number of warm days, we do so by counting all the data points that are greater than 90th percentile of the baseline period within the last 30 years. We can use numpy method **np.where** which return 1 where max_temp is greater then max_temp_pc90 and returns 0 otherwise. \n",
     "\n"
    ]
   },