You Know It's Humid When . . .

This post has come about because of something posted on Facebook.  

Something like the photo below with this caption, " Monsoon Season in GJ !  I love it . . . mornings and evenings around 70 degrees, no humidity, fresh air . . . putting on a jacket to go feed the critters and look for Wile-E Coyote.

Evidently, there are those here in Grand Junction who chose to disagree with the "no humidity" part of that caption.

They seem to be more than just disgruntled about the amount of humidity we are experiencing lately.

OK. So, it is more humid lately than normal because we are in the midst of Monsoon Season.

I do confess that I mis-spoke by saying NO HUMIDITY.  Sorry.

BUT, there is a difference in the humidity here and the humidity, let's say, in Oklahoma. 

Oh no, you say.  Humidity is humidity no matter where it's located.

That's where I beg to differ.

So, when one of my Facebook friends went so far as to check on the humidity here and the humidity there and then posted that Grand Junction had more than Tulsa, that's when vague memories of teaching eighth grade science came cob-webbing through.

Yes. Yes. I do remember.  There's a chart for humidity and temperatures.  A chart like the one below:

Let's see now . . . yesterday morning my themometer said it was 75 degrees.  Oops.  Seventy-five isn't even on the chart.  So, let's say it was 80 degrees. Even if there was 95%humidity (which it wasn't that high no matter how much those friends squawked). we're still in the yellow portion of the chart.  Even at 80 degrees and 100% humidity, it still only feels like it's 87 degrees.  Stop whining.

Now, let's talk about Oklahoma.  My daughter lives there.  I know she does.  I talked to her yesterday just after she mowed the yard at 6:00 a.m. (in Oklahoma).  At that time, it was already 95 degrees and it reached 102 degrees later in the day.  The humdity there was a mere 55%. 

OK. So, you've already found where those two numbers intersect on the chart. Yup. The red portion which denotes:  Extreme Danger !  Therefore, the temperature felt like it was 130 degrees.

WAIT! Humidity of  only 55%?  Why does it feel more humid than that.

What’s going on here there ? Meteorologists use the term humidity pretty loosely. Most of the time “relative humidity” is shortened to just “humidity”. But the word relative is very important to the term and can lead to confusion when dropped. 

You see, warm air can hold a lot more moisture than cooler air. As temperatures go up in a steady linear pace, the air’s ability to hold water goes up in a rapid exponential pace. So the “humidity” is simply “relative” to the temperature.

The thing to remember is an airmass at 100° can hold a lot of water. So even at a low 40% relative humidity, it feels just a wee bit sticky.

This is where the word "dewpoint" enters the scene.

ENTER:  Dewpoint.

 Remember the dewpoint is what the temperature would have to fall to for the air to be saturated at 100% relative humidity. This is why the temperature cannot fall below the dewpoint. There cannot be 110% relative humidity.

Using the chart above you see 94° with only 60% RH makes it feel like 110°. The dew point would be about 78°.

Now let’s drop the temp from 88° to 78° (wouldn’t it be nice if it were that easy). Keeping the dewpoint at 61° raises the relative humidity from 40% to 56%. So getting sweat to evaporate and cool your skin on the 78° day would take longer. However, you wouldn’t need to sweat as much since its only 78°.

Thus the day and the place with higher relative humidity doesn’t feel as humid since it goes hand in hand with cooler temps.

Enter another word . . . or two:  Heat Index

The heat index (HI) is an index that combines air temperature and relative humidity in an attempt to determine the human-perceived equivalent temperature — how hot it feels, termed the felt air temperature. The human body normally cools itself bysweating which evaporates and carries heat away from the body. However, when the relative humidity is high, the evaporation rate is reduced, so heat is removed from the body at a lower rate causing it to retain more heat than it would in dry air. Measurements have been taken based on subjective descriptions of how hot subjects feel for a given temperature and humidity, allowing an index to be made which relates one temperature and humidity combination to another at a higher temperature in drier air.

Moral of this story:

Evidently, everything is relative . . .even humidity !

But, I digress.  The title of this post is:

"You know it's humid when . . .

your glass has more water on the outside than on the inside."

you step outside and your glasses fog up."

your air conditioner acts more like a sprinkler system than it does an AC."

you are sweating just reading this post."

you washed the dishes yesterday, and they're still draining."

you lift your blouse so that the sweat running between your boobs cools your chest."

the only reason you take a shower is to rinse the salt off your skin."

after taking that shower on Monday, you're still wet on Wednesday."

there is moss growing on the shady side of your car and you drove it yesterday."

you drive through the car wash to remove the moss and it won't dry."

your naturally straight hair has taken on a life of it's own and is now in ringlets."

 . . . OK . . . you're next . . .

"You know it's humid when . . .

 

Comments

[Andrea]

LOL!!!!! Well now I know why I feel like I'm being asphyxiated in Texas. And here, now that our humidity has sky rocketed into the 70-80%.

[AC]

We had some really high RH on top of pretty fair heat a few days ago, but I'm not sure what the actual numbers were. We've cooled down after several hot days. It will only be ~75/50% today, which is very nice.

Now, all of this heat index disregards wind chill. I'm just sayin.

Used to do RH/AH/Dewpoint problems with my classes. Most did not find it very easy.

[Sayre]

I "know" about all that humidity/relative humidity, heat and dewpoint stuff (though I haven't memorized the charts)... It's been drilled into our heads since they came up with it a few years ago.

Once I had an old, somewhat leaky Volvo. It had rained the previous day, then was hot the next. I'd parked the car at work and after a full day in the sun, I got into it and literally could not breathe. It was like trying to breathe in soup. Of course, there are days that feel ike that just walking around in the open here.

[Janis]

Wow what a lesson in humidity!!! I just pay attention to the DEW point...when it gets into the 60's I know its going to be a sticky, muggy day! One good thing about this neck of the woods...we get breaks from the Dew point...it goes up n down like a yo yo!! Florida on the other hand...once the Dew point sets in..its stays that way 24/7 for months!!!

[Sandy]

I hear you! I left my hometown where it was a lovely 110 degrees with like 0 percent humidity and went to Corpus Christi where it was 95 degrees with 75 percent humidity. Just to save you time, that's a heat index of approx. 128 degrees. I glowed, ladies, I glowed. There was glow running down my face so badly that I actually bought a golf visor and turned into the ultimate tourist!

[Puppysitter]

That is really interesting, thanks teacher! I did not know WHY, but I've never forgotten what it felt like to move to South Carolina, in August, from Montana.

[Pamela]

...when I can practice treading water in the back yard and there is no swimming pool

(I was introduced to humidity when we visited Delaware, Washington DC etc back in 96. It was so uncomfortable.)