How am I able to see clouds at night?

Because you live in an urban area, you are seeing the clouds because of the light pollution of street lamps shining on them. If you were on a perfectly dark sky you couldn't see them. read more

Actually, being able to see clouds at night is a test for how light-polluted an area is. Under truly dark skies--like say, the Texas Star Party--nighttime clouds are invisible and appear as black areas against the starlit sky. read more

A lot of the time people who live in cities don't realise how many stars there are in the night sky - because the light pollution from cities keeps you from seeing them. read more