Weather data updates

[ks905383]

In addition to responding to comments in #77 ,

Reorganization

• This section has been split up into more and shorter subsections for ease of reading
• Introductions and concluding text has been added and tweaked to better guide the reader

Minor Fixes

• Changing var to variable in examples, since var is generally used as a function name (variance, in xarray, for example)
• Replacing links to papers with DOIs whenever possible, which will hopefully be more stable in the long run

[ks905383]

Most of the conflicts are due to me manually messing around with the requirements, I think, before they were fixed in #82 . I'll see if I can manually fix them.