Monday, July 16, 2007

Dewpoint VS. Relative Humidity

The long debate over the use of "Relative Humidity" and "Dewpoint" continues. This email came into the Newsroom today:

Dear Sir,
I enjoy watching the weather and Ryan Vaughan. However, he puts so much emphasis on the dew point and talks about the humidity but seems to intentionally avoid ever telling us the relative humidity. Why? It would be nice to know both. Thank you, Jim

I would bet that many of you would be surprised to know that our Relative Humidity was between 45-55% this afternoon. (You thought it was 80-90%...right?) Most people would be surprised because they have no idea what the Relative Humidity is OR what it is "relative" to... This article (click here) is the best article to explain why the "Dewpoint" is a better value to use.

I show the "Dewpoint" (or Dew Point to some) and then show a graphic explaining the impact of the Dewpoint. I call it the "Muggy Meter". It tells the "weather story" much better.

Before you jump down my throat and tell me how wrong I am, read the article and think about it for a few minutes. I'm taking a small step toward breaking the old habits of TV Weather, but I'm not going to fold on this one!!! Dewpoint is a better measurement!!! LOLFor those of you that still want to see the Relative Humidity, I do post it on my Current Conditions page. Although it is there, I RARELY mention it! I'll open this up for debate in the comments section...

I have to get home! Take care...

EDIT--- Here's another good article.


The Professor said...

Hey Ryan,
I'd love to be educated on something else. I can understand the concept of a 30% chance of rain. Even a 70% or 100% chance of rain. I can't seem to wrap my brain around a 50% chance of rain.

There's ALWAYS a 50% chance of rain. It either will rain or it won't. LOL!

Is ther some complicated formula or methodology that sometimes results in a 50% chance? Why not just bump it to 49% or 51%?

Great blog, by the way.

Jason H said...

Ryan I usally think your wrong about everything, but not this time.;-)"j/k". I agree with you 110%. I will stand with you in the good fight"Dewpoint Vs. Relative Humidity"!!!


Wander said...

Thanks for the explanation, especially for some of us "older" folk who have grown up with hearing about humidity all of our lives.
I'm with the professor, would you please explain the meaning to the percentage of rain chance's?

Heidi of The Ozarks, relatively speaking that is said...

It is important for you to give your audience a quick impression of what to expect, and that's exactly what you do in the limited time you have to present the weather on-air. If you throw too many variables or technical terms into the equation, many folks will undoubtedly become confused and/or "tune you out." Emphasizing the importance of dewpoint to your viewers is the most reasonable, responsible thing to do from many angles, all of which are covered in your original post or in the links provided.

I think it is true that in some other areas of the country, people might be used to seeing more emphasis on relative humidity. Although I did not watch a local TV weathercast at the time, when I lived in Arizona I do remember that relative humidity was a factor that was to be kept in mind, especially during monsoon season. But regardless, in the South, dewpoint is the way to go. :-D

...And besides, your "Muggy Meter" cartoon-character, with his tremendously slack jaw that drags around his ankles, will one day stand shoulder-to-shoulder with the many other great super-heros of our time -- Oh yes he will! I think he should be called Magnus, the Muggy Meter Man, as the name Magnus means large, a gesture toward his widely-gaping mandible. Or he could be called Myles, which means inventor of the corn mill. Perhaps KAIT could conduct a poll, so that viewers at home can have the final say?

I would like to add that the K-8 Weather Watchers report relative humidity, for those who would like to know.