Curved earth RefractrivityTable creates inhomogeneous array

[twybo]

Issue
Creating a radiotools.atmosphere.refractivity.RefractivityTable with curved=True throws an error by the attempt at creating an inhomogenous numpy array. In get_cached_table_curved_atmosphere, the list self._distances is appended with arrays of different sizes (distances = np.arange(...) with variable ending and fixed stepsize). Creating an array from this (line 234) throws the error.

Minimal working example

from radiotools.atmosphere import refractivity
tab = refractivity.RefractivityTable(curved=True)

radiotools/radiotools/atmosphere/refractivity.py

Lines 222 to 234 in 60d0be0

	for zdx, zen in enumerate(self._zeniths):
	max_dist = atm.get_distance_for_height_above_ground(self._max_heigth, zen, 0)
	distances = np.arange(0, max_dist, self._distance_increment)
	refractivities_for_distances = np.array([self.get_refractivity_for_height_tabulated(
	atm.get_height_above_ground(d, zen, observation_level=0)) for d in distances])
	refractivity_integrated_table = np.cumsum(refractivities_for_distances * self._distance_increment)
	self._distances.append(distances)
	self._refractivity_integrated_table.append(refractivity_integrated_table)
	self._distances = np.array(self._distances)