|Sun & Antisun
Anticrepuscular and crepuscular rays of startling intensity imaged by Jim Niebur at Omaha, Nebraska. ©Jim Niebur
The top image looks eastwards away from the sunset point. The sun was just setting at ground level but still above the horizon higher up and illuminating the clouds.
Long bluish shadows cross the sky to apparently converge at the antisolar point directly opposite the sun. The shadows are in reality nearly parallel and only seem to converge by perspective.
'Antisolar' might be a more descriptive name for these rays rather than anticrepuscular implying that they are against the twilight.
The lower image looks sunwards. The shadows are cast by banked clouds low on the horizon or beyond it.
Most cloud shadows are three dimensional in the sense that they are long tubes of unlit air. Here they are probably two dimensional shadows cast upon and along a cloud layer - Hence their intensity.