installation.md

@@ -108,14 +108,17 @@ General Linux Install
 
 Tested 2022-09-26 on Ubuntu (Kubuntu) 22.04
 
-This isn't really any smaller than the miniconda install, but it does limit dependencies to your distribution and Python's PyPI.
+Assuming most of the required modules are already installed, this might be as small as 100 MiB. If most modules are needed (or you omit `--system-site-packages`), it might be 600 MiB, which is similar to a miniconda install.
 
 You'll need libgeos-dev (`sudo apt install libgeos-dev`) and likely various libqt libraries. 
 
 ```
 git clone https://gitlab.ssec.wisc.edu/evas/UW-Glance.git glance
 cd glance
-python3 -mvenv venv
+# You can omit "--system-site-packages" to ensure you're using fresher versions
+# of software from PyPI instead of what is already installed. The install will
+# almost certainly be much larger.
+python3 -mvenv --system-site-packages venv
 source venv/bin/activate
 pip install pyqt5 numpy matplotlib mako mock scipy pillow cartopy pyqt5 netcdf4 h5py
 cd pyglance/