Yes, I can. Partly/Mostly sunny only refers to the daytime. After the sun goes down, meteorologists change to partly/mostly cloudy because there's not anything constant in the sky except the moon and that disappears at least once a month. Partly/mostly cloudy can be used during the daytime when 3-7/8ths of the sky is covered with clouds but if you want to be specifically accurate, you would use partly/mostly clear.
Anyway, Brutus will know none of this so Wilberforce will just have to stay confused.
Although, partly cloudy or partly sunny mean the same thing (3-5/8th cloud coverage) so the skies aren't actually changing so this is wrong anyway.