Explain polar versus geographic coordinates in documentation

[geanders]

In some of our functions, we convert to use polar coordinate conventions rather than geographical ones, to align with using u- and v-components of forward distance of the storm. It would be helpful to explain this somewhere in the documentation, including with pictures. Also, we should check that, if we output something like the surface wind direction, that we move it back to a geographical direction that would make sense with mapping functions.

There are nice write-ups on differences in these coordinate systems at:

• https://vvvv.org/blog/polar-spherical-and-geographic-coordinates
• https://kartoweb.itc.nl/geometrics/Coordinate%20systems/coordsys.html
• https://www.skillsyouneed.com/num/polar-cylindrical-spherical-coordinates.html

[geanders]

Look up as well more on azimuthal