sunset, dusk, evening
旰 centers on the late part of the day when the sun is setting: sunset, dusk, or evening.
旰 combines 日 (sun) with 干, which likely contributes the sound. The character expresses the time when the sun is declining.
The sun 日 is beside 干, which looks like a drying rack. Picture the sun hanging low on a drying rack at sunset, marking the evening.
For カン, imagine a can of evening light: as the sun sets, someone opens a can and the warm dusk light spills out. Can -> カン.