default implementation that uses user-supplied params. Currently, the
only parameters are
/environment/params/base-wind-speed-kt
/environment/params/gust-wind-speed-kt
but others will show up soon (i.e. sheer, variable direction, variable
visibility, etc.). To activate these properties, you have to
configure --with-new-environment.
The gusting function is simplistic and needs to be replaced with
something better, though it doesn't feel too far off.
