What do you mean, it's partly sunny?

The local sunny weather forecast means that the local time is sunny, and there may be a short cloudy day. Usually, what meteorologists call sunny days, cloudy days and cloudy days are classified according to the amount of clouds in the sky, which is divided into ten equal parts. Less than 30% is sunny, 30% to 80% is cloudy, and thin sunlight can penetrate clouds. More than 80% is cloudy, so sunlight rarely penetrates through the clouds.