Add testing and whatsnew

Author: AdamRJensen

docs/sphinx/source/whatsnew/v0.13.1.rst

@@ -6,6 +6,9 @@ v0.13.1 (Anticipated September, 2025)
 
 Breaking Changes
 ~~~~~~~~~~~~~~~~
+* Change refraction for solar elevation angles between 85 and 90
+  degrees to be calculated rather than set to 0 in
+  :py:func:`~pvlib.solarposition.ephemeris`. (:pull:`2524`)
 
 
 Deprecations

tests/test_solarposition.py

@@ -964,3 +964,15 @@ def test_spa_python_numba_physical_dst(expected_solpos, golden):
                                               temperature=11, delta_t=67,
                                               atmos_refract=0.5667,
                                               how='numpy', numthreads=1)
+
+
+def test_ephmeris_refraction_85_90_degrees():
+    # Test that refraction is calculated rather than set to zero
+    # for solar elevatoin angles between 85 and 90 degrees
+    # PR#2524
+    # The below example has a solar elevation angle of 87.9
+    result = solarposition.ephemeris(
+        time=pd.date_range('2020-03-23 12', periods=1, tz='UTC'),
+        latitude=0, longitude=0)
+    refraction = (result['apparent_zenith'] - result['zenith']).iloc[0]
+    assert refraction == -0.0005818446332597205