As a child I believed that the dark-colored "night clouds" that are visible after sunset are made of special dark-blue water vapor. At some point in my adult life I realized that this belief had persisted in my mind uncorrected!
A childhood belief about weather

others believed things like this
- I was born brunette with brown eyes and dark hair, i thought people with blue eyes, had water in them.Anon
- I used to believe that when it would be raining the white clouds lost to the dark clouds.— janet
- I used to believe clouds became cotton candy at sunset because they turned pink— amme
- I was told as a child to eat the dark parts of a banana, because it was really brown sugar.Anon
- I belived carrots made you see in the dark Anon
- The line 'The dark sacred night' in What A Wonderful World is actually 'The dogs say goodnight'...— rebecca