When I hear a forecast call for partly sunny or partly cloudy skies, I always wonder about the difference? Is it a glass half full/half empty situation, or is there science behind it?
It makes sense that when it is partly sunny, there is more sun than clouds, and vice versa. However, the answer, according to some experts, is not that simple. The Weather Forecast Office in Montana explains that there is no actual difference between partly sunny and partly cloudy. Rather, it is up to the weather person to emphasize sun or clouds.
Still, there are opinions that differ. Some experts at the National Weather Service, for example, prefer a more scientific explanation. They define partly sunny as a predominant sky condition that is 3/8 to 4/8 clear, and partly cloudy as a predominant sky condition with 3/8 to 4/8 cloud coverage.
I suppose it makes little difference since both forecasts call for a mixture of both sun and clouds. Still, the optimist in me will always see the sky as partly sunny over partly cloudy any day.