exposures phrasing

Author: sarah-hlsn

doc/user-guide/climada_engine_Impact.ipynb

@@ -170,7 +170,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Exposures are geopandas dataframes with at least columns 'latitude', 'longitude' and 'value' of exposures. They are either defined as a series of (latitude/longitude) points or as a raster of (latitude/longitude) points. Fundamentally, this changes nothing for the impact computations. Note that for larger number of points, consider using a raster which might be more efficient (computationally). For a low number of points, avoid using a raster if this adds a lot of exposures values equal to 0. \n",
+    "Exposures contain a geopandas dataframe with a geometry column, and a 'value' column of exposures (e.g. monetary value, population count etc.). They are either defined as a series of (latitude/longitude) points or as a raster of (latitude/longitude) points. Fundamentally, this changes nothing for the impact computations. Note that for larger number of points, consider using a raster which might be more efficient (computationally). For a low number of points, avoid using a raster if this adds a lot of exposures values equal to 0. \n",
     "\n",
     "We shall here use a raster example.\n",
     "\n",