Kevin Myatt is The Roanoke Times' weather columnist.

kevin.myatt
@roanoke.com
981-3341

Weather with Kevin Myatt

Recent columns

• We got graupel, but not on official record
• Moisture could get caught up in cold blast
• Forecast for Weather Journal: Partly print, with frequent Internet
• Column archive

Read the Weather Journal blog

• For now, it looks like a quiet, mostly mild week ahead for SW Virginia
• Coldest morning of winter so far likely across much of Southwest Virginia; Tuesday precipitation looking doubtful
• UPDATE 8:45 AM, 2/11: Blustery winds for all, snowflakes for most, white ground for many, multiple inches for few
• Weather Journal blog

#swvawx on Twitter

@KevinMyattWx

• Follow Kevin on Twitter at @KevinMyattWx

Possibly the most asked question in weather has nothing to do with hurricanes, how much snow we'll get this winter or global warming. I get this question a lot, by e-mail, by phone, from people at work and at church. I'm not the only one.

"Rarely will I make it through a Rotary meeting or church senior club speech without that question coming up," said WDBJ Channel 7 meteorologist Robin Reed, responding to a query I sent by e-mail to some local meteorologists.

The question: What is the difference between partly cloudy and partly sunny?

I thought I knew the answer, definitively and decisively. Again, I'm not alone.

"I believe the official definition of 'partly sunny' actually means slightly more clouds than sun, whereas 'partly cloudy' means more sun than clouds," said WSLS Channel 10 meteorologist Jamey Singleton.

That was my understanding, too. Partly sunny means that it's only a part sunny and mostly cloudy. Partly cloudy means that it's only a part cloudy and mostly sunny.

I was sure I had grasped this secret of the universe. Having been asked the question by a reader one day, I rather cockily did some Internet research, quite certain that it would confirm my insight into the partly cloudy/partly sunny issue.

After reading through many different reputable weather sources online, the clouds began blotting out the light.

The issue itself is, at best, partly cloudy. Or, perhaps, it's partly sunny.

"Partly cloudy and partly sunny are essentially the same thing," said David Wert, meteorologist-in-chief at the National Weather Service office in Blacksburg. "Both are used for conditions when the average amount of opaque cloud cover ranges from 45 percent to 75 percent. We usually use 'partly sunny' for daytime conditions, and 'partly cloudy' for nighttime conditions under these situations. It wouldn't make too much sense to use 'partly sunny' for a nighttime condition."

Though the percentages vary slightly in different accounts, I found many references to partly cloudy and partly sunny describing the same range of cloud cover.

I also found references to the only difference being that partly sunny is used for day and partly cloudy at night.

A few sources also said that partly cloudy was less cloudy than partly sunny, like I thought.

But, apparently, there is also a widespread public perception that "partly sunny" sounds more bright and cheery that does "partly cloudy."

"Before I studied weather in college, I always thought 'partly sunny' meant more sun, because you actually hear the word 'sunny,' " Singleton said.

"At a recent American Meteorological Society conference, a paper was presented that suggested television meteorologists simply say partly cloudy and avoid the confusion," Reed recalled. "That brought a howl of protests as some broadcasters felt they needed the more optimistic 'partly sunny' in their arsenal to put people in a better mood about the weekend forecast."

So, then, is the partly cloudy-partly sunny matter a Rohrshach test? Is it a matter of seeing the sky half empty or half full? Perhaps.

"If you think about it, though, there's no way to win," Singleton said. "You could call for either one and still be considered wrong. If that one cloud is over your house, it's just cloudy. If the cloud is over your neighbor's house, then it's plain ol' sunny where you live."

"Kids don't really seem to care," said Reed. "As long as some sun is shining through the clouds, it's a sunny day."

Perhaps we should defer to the mouths of babes when the experts are only partly clear about partly cloudy and partly sunny.