If you have seen on a clear sky a reddish glow in the opposite direction to the sun rising or setting, just above the horizon. Before the sun comes above the horizon in the morning or after the sun has gone below the horizon end of the day. You were looking at an alpenglow, not to be confused with the alpenglow my face gets when I have eaten chocolates in the mountains. No clouds are needed for the reddish glow, but you do need precipitation, ice crystals or particulates in the lower part of the atmosphere. The light gets reflected off them and you get a beautiful reddish glow above the horizon. After sunset, you can get this even without the mountains, but the snow covered mountains do add to the beauty.