What is the difference between partly cloudy and mostly sunny?

Question

What is the difference between partly cloudy and mostly sunny?

Answer 1

Partly Cloudy:   3/8 - 5/8 opaque* clouds

Mostly Sunny:  1/8 - 2/8 opaque* clouds

individually this would mean nothing to me, but you can at least compare the two

Answer 2

Nothing, good observation.

Answer 3

there is no difference

Answer 4

Weather recording is an old science that really got to move when radio communication became possible at the start of the 20th century. Remote places like tiny islands on the ocean, and ships were able to report their observation thus enabling the drawing of maps and resulting forecasts.

But the data had to be compiled in a standard format. It was then decided that the cloud coverage was to be given in division of eights. 4/8, for example would be half of the sky cloudy.

Partly cloudy is - in aviation - called scattered. If more than half of the sky is covered then it is called broken. If only a few clouds are expected to appear in the sky, it is simply called, few.

So, for an aviator, partly cloudy would be SCT (scattered) and mostly sunny would be FEW (few) when reading the METAR (present weather at the airfield) or TAF (9 or 18 hours forecast).