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Main Forums => The Roundtable => Topic started by: 230RN on April 11, 2023, 08:58:49 AM

Title: Nine percent humidity today
Post by: 230RN on April 11, 2023, 08:58:49 AM
https://forecast.weather.gov/MapClick.php?lat=39.7836&lon=-105.1675&unit=0&lg=english&FcstType=graphical

(Current for when you click on it. Nine percent around 3 PM MDT.)

You gots to drive two-three miles before bumping into a water molecule.

Eyeball shriveling, nose-pickin' time.  But good for guns, swamp coolers, drying laundry.

Probably bad for fire danger ratings.

Beef jerky can be made by leaving a slice out for half an hour.

"Wet your whistle" becomes a meaningless term.

Deodorant spray dries before it hits your armpit; spit don't hit the ground.

Dead things don't decay, they just mummify.

I remember being surprised to see "bone dry" iused as a technical term on a lecture bottle of "Bone Dry Carbon Dioxide."   Sample: https://www.airgas.com/product/Gases/Specialty-Gases/Carbon-Dioxide---Specialty-Gas/p/CD%20BD200

"But it's a dry heat..."  Yeah, but holy crap, nine percent?

Terry, 230RN

Edited to change sry heat to dry heat.
Title: Re: Nine percent humidity today
Post by: MechAg94 on April 11, 2023, 09:10:33 AM
Sounds like when I was at a site near Las Vegas about this time last year.  For someone who lives on the Texas Gulf Coast, that is just alien.  Dry is 60% down here. 

When I drove back into Texas, it was great to see clouds, green grass, and feel moisture on my cheek. 
Title: Re: Nine percent humidity today
Post by: WLJ on April 11, 2023, 09:15:27 AM
Just checked my weather station, 57% here in Louisville. Sort of dry and zero chance of rain most of the week which is unusual for this time of year here.
Title: Re: Nine percent humidity today
Post by: RoadKingLarry on April 11, 2023, 09:18:33 AM
89% here this morning.
Title: Re: Nine percent humidity today
Post by: 230RN on April 11, 2023, 09:27:09 AM
57%?
89%?

That's percentage saturation of water vapor, real water, H2O, right?  Holy cow, how come youse guys ain't drowning in your own air?

I saw wind velocity was actually zero about an hour ago.  Verrry rare, but off the graph by now 7:25 AM MDT.

Cue Twilight Zone theme.

Title: Re: Nine percent humidity today
Post by: WLJ on April 11, 2023, 09:30:20 AM
Last 30 & 90 days

Title: Re: Nine percent humidity today
Post by: Nick1911 on April 11, 2023, 09:33:51 AM
57%?
89%

That's percentage saturation of water vapor, real water, H2O, right?  Holy cow, how come youse guys ain't drowning in your own air?

I saw wind velocity was actually zero about an hour ago.  Verrry rare, but off the graph by now 7:25 AM MDT.

Cue Twilight Zone theme.

It is not.

It is the percentage of water vapor in the air relative to what the air can hold at that temperature.

As it gets warmer, air can hold a lot more moisture.  This is why relative humidity is somewhat misleading.

If you want to know absolute humidity, that's typically given in grains per pound of air, in US customary units.

At 40F, air can hold about 38 grains of water per pound.  At 90F, it can hold north of 210 grains per pound.

If the total amount of water in the air stays constant and the temperature increases, RH% will drop.

https://www.engineeringtoolbox.com/docs/documents/816/psychrometric_chart_29inHg.pdf

X axis is temperature, Y axis is absolute humidity.  Note the RH% lines that curve through the chart.
Title: Re: Nine percent humidity today
Post by: HankB on April 11, 2023, 09:42:14 AM
When I was last in Tucson, temperatures were in the 104-106 F range, and dewpoints were in the 20s. It didn't feel terribly hot - in fact, it was almost pleasant. Sun was pretty intense, though. Some restaurants with outdoor seating had misters going, which helped cool things down a little, even in the shade.

Here in central Texas (Austin area) when we're in the low 100s, dewpoints - even in the middle of a drought - are typically above 60, sometimes edging into the 70s. THAT feels unpleasant - when you sweat up, you stay damp as long as you're outside.
Title: Re: Nine percent humidity today
Post by: 230RN on April 11, 2023, 09:48:09 AM
It is not.

It is the percentage of water vapor in the air relative to what the air can hold at that temperature.

As it gets warmer, air can hold a lot more moisture.  This is why relative humidity is somewhat misleading.

If you want to know absolute humidity, that's typically given in grains per pound of air, in US customary units.

At 40F, air can hold about 38 grains of water per pound.  At 90F, it can hold north of 210 grains per pound.

If the total amount of water in the air stays constant and the temperature increases, RH% will drop.

https://www.engineeringtoolbox.com/docs/documents/816/psychrometric_chart_29inHg.pdf

X axis is temperature, Y axis is absolute humidity.  Note the RH% lines that curve through the chart.


I knew that.  Just minimalized it so I wouldn't trash up my post for the sake of the humor.

No offense, but that's pretty standard knowledge, and I've explained it myself a couple of times but thanks for the definitive explanation.

I was interested to note that WLJ's graphs inclided a confidence band.

Terry

Title: Re: Nine percent humidity today
Post by: Nick1911 on April 11, 2023, 09:49:47 AM
Ah, guess that joke went over my head.  Better drink some more coffee before posting.  =)

I sometimes forget that standard knowledge in this group is leaps and bounds ahead of the general population.
Title: Re: Nine percent humidity today
Post by: WLJ on April 11, 2023, 09:50:45 AM
Temps last 30 days, includes dew points

Title: Re: Nine percent humidity today
Post by: RoadKingLarry on April 11, 2023, 10:24:13 AM
57%?
89%?

That's percentage saturation of water vapor, real water, H2O, right?  Holy cow, how come youse guys ain't drowning in your own air?

I saw wind velocity was actually zero about an hour ago.  Verrry rare, but off the graph by now 7:25 AM MDT.

Cue Twilight Zone theme.

This time of year we measure our morning dew fall in inches.
Title: Re: Nine percent humidity today
Post by: Brad Johnson on April 11, 2023, 10:34:53 AM
Texas Tech has a series of weather stations dotted around the region - Texas panhandle and Rolling Plains areas. Realtime readings (well, every few minutes, anyway...). Great for tracking common meteorological info.

https://www.mesonet.ttu.edu/

They also have a radar page which is much less bloated than the new NWS product. More like the old WSR88D page.

https://www.mesonet.org/index.php/weather/radar/KLBB

Brad
Title: Re: Nine percent humidity today
Post by: JTHunter on April 11, 2023, 03:35:23 PM
Here's another example of RH for you.
On 6/2/76, I was on a zoology field trip from my university and we were entering Joshua Tree Natl. Monument.  The bus boiled over on the way in and, as it turned out, the park office was already closed for the summer!  A bunch of us went climbing on the rock piles (200-300' high) near where the bus had to stop and two groups raced up two of these piles to see who got to the top first.  While it was fun, we all ended up winded and sweaty.  We went over and stood in the shade of the bus and there was a slight breeze, maybe 3-8 mph.  Within 10 minutes, we were cooled off and dry again.  The prof estimated the RH at ~5% at the time.
  =D
Title: Re: Nine percent humidity today
Post by: 230RN on April 12, 2023, 10:40:15 AM
There have been days where I didn't have to use a towel after a shower.  I did, out of habit, but I didn't have to.

Not much trouble with humidity-caused gun rusting here in Commierado.

A little different from NYC, where I was born and raised.  We didn't have guns, but tools would rust no matter what you did.  It seemed the salt air didn't help; salt spray from the ocean waves would evaporate, leaving teeny-tiny particles of sea salt to blow around.  Salt + tools + humidity = rust.

Terry

REF (Corrosion due to humidity): 
Hatcher's Notebook says a great deal about humidity in his chapter on "Gun corrosion and ammunition developments."

One of the things that drove the Ordnance Department nuts with regard to the old corrosive primers was the fact that sometimes barrel corrosion developed weeks after thorough cleaning, sometimes it didn't.  The mystery was solved when it was discovered that humidity over 50% caused it, and that percentage of humidity might not be reached for a random time after the cleaning.  See pages 348-349, Hatcher's Notebook

Title: Re: Nine percent humidity today
Post by: Brad Johnson on April 14, 2023, 02:42:14 PM
If it's any consolation, it's snowing in Fraser / Winter Park today.

https://youtu.be/hQeFtIAmlqQ

Brad
Title: Re: Nine percent humidity today
Post by: 230RN on April 14, 2023, 07:37:53 PM
^
Well, at 8700 feet, Fraser's kind of "across the (vertical) 'border' " of about 6500 feet, more or less.

In fact, it's snowing pretty good here near Golden at ~5600 feet.

Fun at night shining a laser out into the falling flakes.  Discovered that one night by trying to take the air temperature with my IR sensor which has a laser beam on it.

Sample:

    (https://m.media-amazon.com/images/I/71DqEQKDwkL._AC_UY545_QL65_.jpg)

"Ooooo !  Sparkles !  Eeeeee !  Pretty !"  Don't have little ones around but the kiddies would probably love it.  (Yeah, even this 84yo kid.)

Don't use the lasers on your gun sights.<"Legal" advice just to cover my own ass.

Terry, 230RN

REF (Current for when you click on it):
https://forecast.weather.gov/MapClick.php?lat=39.7836&lon=-105.1675&unit=0&lg=english&FcstType=graphical
Title: Re: Nine percent humidity today
Post by: Perd Hapley on April 15, 2023, 08:29:47 PM
We had a funeral in Urbana IL this morning, and were leisurely making our way back. We were coming south from Springfield, and as soon as we got onto 270 West, toward St Louis, we heard a tornado warning. Didn't have any place to go, so we eventually parked under a gas station canopy, and came inside. Or at least, the wife is inside. I'm right outside the door, watching. Nothing but rain, so far.

Back on the road now.
Title: Re: Nine percent humidity today
Post by: 230RN on April 15, 2023, 11:00:14 PM
Just a warning?  I wouldn't have taken evasive / sheltering action unless one was visible.  At least in a vehicle, you can try to head at right angles to its perceived path. Or possibly outrun it.

Opposing views?  Enlighten me, please.

Yeah, some guys got killed in a car, but they were storm chasers and deliberately placed themselves in danger and got themselves stuck in an inescapable situation and the car went bouncity bouncity bouncity with them inside going thumpity thumpity thumpity --although I think IIRC, one got ejected from the car while it was going bouncity bouncity bouncity.

Tragic, but I feel as bad for them as I would for a skydiver whose 'chutes didn't open.  Splattery splattery splattery.  Or a technical rock climber who lost his its her grip. Tumblity tumblity tumblity.  Owie owie owie.  Recovery recovery recovery by helicoptery.

Terry, 230RN
Title: Re: Nine percent humidity today
Post by: RoadKingLarry on April 15, 2023, 11:14:16 PM
A "warning" means there is an active tornado in the vicinity. That means it's time to get the cameras out  =D .

Can't always see 'em coming. At night unless you see the power flashes where it's taking out the lines or if it's rain wrapped you might not know it's on you till you are well on your way to The Land of Oz.
Title: Re: Nine percent humidity today
Post by: Perd Hapley on April 16, 2023, 01:00:25 AM
Just a warning?  I wouldn't have taken evasive / sheltering action unless one was visible.  At least in a vehicle, you can try to head at right angles to its perceived path. Or possibly outrun it.

Opposing views?  Enlighten me, please.


"Just a warning" means you're in more immediate danger than a "watch." It means you should get in the cellar. (Or get the camera, cuz something might go down real soon.)

 I once had the pleasure of being on the freeway, going right past Lambert Field, right around the time it was being wrecked by a twister. Got no desire to relive the experience, in the middle of featureless Illinois farmland, where there's nowhere to hide.
Title: Re: Nine percent humidity today
Post by: RocketMan on April 16, 2023, 07:40:45 AM
Just a warning?  I wouldn't have taken evasive / sheltering action unless one was visible.  At least in a vehicle, you can try to head at right angles to its perceived path. Or possibly outrun it.

Opposing views?  Enlighten me, please.

Terry, 230RN

You should seek shelter, not try to outrun a tornado in a car.  Why, you ask?  Lots of high falutin' reasons given in our storm spotter and chasing training, all boiling down to that in a car you are limited by where the road network goes, by the other panicky fools out there driving with you, and by the tornado's unpredictable behavior.
The road network often does not go where you want it to when the tornado is trying to climb into your trunk.  This should be self-explanatory.
Panicky fools have a very annoying tendency to do foolish and unexpected things as they drive. They turn randomly, crash, clog up the roads, etc., thereby thwarting your best laid plans to drive away from the tornado.
Tornados themselves often change their direction of travel.  When they do, it's frequently a turn to the right.  If you have committed to a direction of travel to skirt around a tornado and then the tornado becomes a "right mover", it can thoroughly ruin your day.
Plus, if the tornado is close by, you have to deal with flying debris, which can be deadly even if you are inside a car.

Edited to add additional info.
Title: Re: Nine percent humidity today
Post by: 230RN on April 16, 2023, 04:42:09 PM
WRT^

"...At least in a vehicle, you can try to head at right angles to its perceived path. Or possibly outrun it."

Bolding added.

Well, sure, but your crazy other driver scenario is true anyhow, tornado or no tornado.  And your remark about those tornado chasers is irrelevant since they weren't trying to escape in the first place.

Certainly, your course of action depends on circumstances, but for the general situation, (A) I wouldn't automatically try to shelter up and (B) My perhaps clouded judgement would be to drive away as noted.  I did shelter my camper under an overpass when some really rough weather occurred.  I got there just in time, the underpass filled up with other vehicles in a hurry. Tornadoes out in the boonies aren't necessarily reported on newscasts, but holy crap, the sky sure opened up and there was a roaring sound but that could have been the hail.

Despite the vagaries of tornado direction-taking, if you have any distance from them at all, my estimation is the best bet is to move away from them...the "right angles" has been recommended by Officialdom, for what it's worth.  They aren't looking for Rocket Man, after all.  "Hey, there's Rocket Man's car !  Let's go git 'im!"

But it depends on what you guess your chances are.  Do you hit with 17 in Blackjack?

Perd did not go into great detail on the situation, so his choice may have been perfectly valid, even under a "warning" alert.  I just wanted to comment on the notion that it seemed automatic.  May have been a good choice given the exact situation.

Terry taps his cards.  "Hit me."

Dealer skids card to Terry.  "Oh, *expletive deleted*it. A five."

Terry, 230RN
Title: Re: Nine percent humidity today
Post by: Perd Hapley on April 16, 2023, 05:51:28 PM
The thing is, Terry, when you're heading down the freeway, at dusk, with heavy cloud cover, you don't know if you're heading toward the possible tornado, or away. If it starts to rain, visibility gets worse. And because (again) it's a rural freeway, your selection of "right angles" is limited, if you're not prepared for off-roading.

In fairness, I think I have heard the advice about moving away at a right angle, but I've also heard you should take shelter in a ditch, if you're outside. I'm pretty sure both of those are meant as backup measures, if you can't get into some kind of of structure.

As it happened, the wind got awfully strong, and there was some hard rain for a while. I don't regret being off the road for that. Plus, we had the car under a canopy, in case of hail. Delayed us about an hour, but we were OK with it.
Title: Re: Nine percent humidity today
Post by: Ben on April 16, 2023, 06:26:23 PM
^^^

Sounds like you made all the right decisions for the circumstances. I wouldn't want to be trying to navigate an escape route at nightfall in an unfamiliar area either. Prudence says "first good shelter and call it good". Plus it would have sucked if you had driven away from the tornado and straight into a hailstorm and had that damage to deal with.

Glad you and the Mrs are okay.
Title: Re: Nine percent humidity today
Post by: Perd Hapley on April 16, 2023, 06:56:25 PM
Thanks.
Title: Re: Nine percent humidity today
Post by: RocketMan on April 16, 2023, 08:40:00 PM
And your remark about those tornado chasers is irrelevant since they weren't trying to escape in the first place.

Not really irrelevant, Terry, as that is the training we received.  We generally did not try to get up close and personal with tornados, instead we would observe them from a distance and provide reports ("ground truth" as it is called) to the NWS.
However, if we found ourselves surprised by a close-by tornado, our training was to seek immediate shelter.  Trying to drive away to escape a close tornado is often impractical if not impossible, especially if you are on a straight stretch of road with no turns or intersections.  Many people have been killed trying to escape tornados in their cars.

Quote
Certainly, your course of action depends on circumstances, but for the general situation, (A) I wouldn't automatically try to shelter up and (B) My perhaps clouded judgement would be to drive away as noted.  I did shelter my camper under an overpass when some really rough weather occurred.  I got there just in time, the underpass filled up with other vehicles in a hurry. Tornadoes out in the boonies aren't necessarily reported on newscasts, but holy crap, the sky sure opened up and there was a roaring sound but that could have been the hail.

Overpasses may seem a logical place to shelter from tornados, but in reality they can be very dangerous due to them causing a venturi effect for tornadic winds.  Wind speed can actually increase significantly as wind passes under a bridge or overpass, blowing people and vehicles out of the supposed shelter.
These people were darn lucky:  https://www.youtube.com/watch?v=lHBZylcxIvw (https://www.youtube.com/watch?v=lHBZylcxIvw)

These people were not so lucky:  https://www.youtube.com/watch?v=xJkDphU5olo (https://www.youtube.com/watch?v=xJkDphU5olo)

Overpasses can be a good place to shelter from large, damaging hail if that is the only threat, however.

Quote
Despite the vagaries of tornado direction-taking, if you have any distance from them at all, my estimation is the best bet is to move away from them...the "right angles" has been recommended by Officialdom, for what it's worth.

Yes, "officialdom" does suggest moving away at right angles if you are sufficiently far away from the tornado, and if the road network allows for that.  If you are out on a straight section of highway with no ability to turn off at an angle away from the storm, then you should pull a u-turn and get the hell out of dodge.
If you cannot do a u-turn then you should take immediate shelter outside the vehicle wherever you can find it.  You do not want to be caught in your vehicle in a tornado.

Quote
They aren't looking for Rocket Man, after all.  "Hey, there's Rocket Man's car !  Let's go git 'im!"

My point was that tornadic storms are unpredictable. 
Title: Re: Nine percent humidity today
Post by: Perd Hapley on April 16, 2023, 09:37:43 PM
We cannot say for certain that the tornadoes are not targeting RocketMan. Their aims are at present unknown.
Title: Re: Nine percent humidity today
Post by: RoadKingLarry on April 16, 2023, 10:11:24 PM
We cannot say for certain that the tornadoes are not targeting RocketMan. Their aims are at present unknown.


 [tinfoil] [tinfoil]
That's what they want you to think
 [tinfoil] [tinfoil]
.
Title: Re: Nine percent humidity today
Post by: 230RN on April 16, 2023, 10:20:09 PM
Good discussion of alternatives and amplification of Perd's events.

Yes.  Thank you, all.

Perd taps cards.  "Hit me."

Dealer slides card toward Perd.

"Great. A four.  Blackjack!"

Terry, 230RN

Title: Re: Nine percent humidity today
Post by: RocketMan on April 17, 2023, 08:39:46 AM
We cannot say for certain that the tornadoes are not targeting RocketMan. Their aims are at present unknown.

I don't know that I have ever been specifically targeted, despite the fact that we had one pass a few hundred yards west of our property in 2017.  It took down a few of the large trees in our yard, but caused no other damage.
It is scientific fact that tornados target mobile homes, single-wide units especially.  Being that this is North Carolina, there are a number of single-wide trailers in the area, and we may have just been collateral damage.   ;)
Title: Re: Nine percent humidity today
Post by: Perd Hapley on April 17, 2023, 09:16:01 AM
Turns out there were 7 tornadoes in the area that night.

https://twitter.com/NWSStLouis/status/1647763914757922817/photo/1

None of them got particularly close to us.
Title: Re: Nine percent humidity today
Post by: JTHunter on April 17, 2023, 01:17:41 PM
Turns out there were 7 tornadoes in the area that night.

https://twitter.com/NWSStLouis/status/1647763914757922817/photo/1

None of them got particularly close to us.

Be glad for that.
They think it may have been an F0 that went over a couple of neighbor's houses Saturday evening.  On my side of the street (east side), a tree in one neighbor's back yard took out the power lines for our side of the street just after 7 p.m.  As of 9 this morning, Ameren STILL doesn't have a "timeline" for when the repairs might be done.
On the west side of the street and one house closer to me, another neighbor had a BRANCH break of of his tree and it took out a wooden garden shed, a 3-season sunroom and still came down on the roof of the garage next door.  Of the cut ends of the branches I can see above the garage roof, the diameters are at least 4-6 inches and get bigger the closer they get to the broken end of the branch.  With the amount of damage this tree has suffered, it isn't likely to survive.  I estimate that the trunk is at least 30" in diameter, between the back yards of two houses and on a rather steep incline.
It's going to be fun trying to take that behemoth down safely.
Title: Re: Nine percent humidity today
Post by: 230RN on April 17, 2023, 03:29:17 PM
They finally cut down a few dead pine trees that were threatening my building right by my bedroom window,.  They were a short distance (20 feet?) from the house and subject to blowing down on the house  in one of our common very strong west winds.

"If you cannot do a u-turn then you should take immediate shelter outside the vehicle wherever you can find it.  You do not want to be caught in your vehicle in a tornado."

Seriously, if worse comes to worst and I were caught out in the open, I'd try to loop my belt around a fence wire or fence post, hyperventilate like mad, cover my eyes, and say Hail Marys as rapidly as I could.  The hyperventilation is in anticipation of a big pressure drop. The Hail Marys are on general principles.

If no such possibility exists, I'd lie down as flat as possible and resort to the Hail Marys.  On general principles.

"Hail Mary, full of Grace, my ass is grass..."

Undoubtedly, expert advice exists on whether to lie down face up or face down. =D

Terry, 230RN
Title: Re: Nine percent humidity today
Post by: RoadKingLarry on April 17, 2023, 03:44:54 PM
Bestest tornado movie EVERS!
(Or, how NOT to survive a tornado)

https://www.youtube.com/watch?v=OgG2jfBfLzI
Title: Re: Nine percent humidity today
Post by: 230RN on April 17, 2023, 04:22:05 PM
^ Interesting entertainment.

At the outset, I wondered about the wisdom of automatically seeking shelter.  Perd probably did the right thing and made 21.

I'm glad we're having this discussion, but sometimes it seems like every ploy reviewed has been met with objections.  I guess the best all around advice is to face the wind, beat your chest, and give a Tarzan yell.

Bur seiously, does the Storm Chasing or other weather organizations have a set of comprehensive strategies for different tornado circumstances with the chances involved in taking different courses of action?

All I've ever heard on the TeeVee is go to the lowest flooe and take shelter in a bathroom.  Nothing (unless I missed it all) about different circumstance while driving (except the right angles thing) or just plain being out in the open.

With me living on the second floor long ago I made arrangements with other tenants on the first floor to take shelter with them in their bathrooms, but senior attrition has eliminated that possibility, so I'm halfway screwed in that regard.

Is there a comprehensive set of plans with alternate situations and solutions available anywhere?

Terry, 230RN

Title: Re: Nine percent humidity today
Post by: RoadKingLarry on April 17, 2023, 05:59:39 PM
Get in a room with no exterior walls and/or no windows. Lowest floor of the building. Underground shelter is best, above ground "safe room" type shelter is a close second.
I've lived in Oklahoma off and on since the mid '60s. Never seen a tornado, never had damage from one and know of no one in my family in the area that has. (knocks wood).
On the other hand in the 12 years I was in the Navy I had the pleasure of direct experience with at least 4 hurricanes.
Title: Re: Nine percent humidity today
Post by: Perd Hapley on April 17, 2023, 06:26:48 PM
Lots of help out there.

https://search.brave.com/search?q=tornado+instructions&source=android

If caught in the open, the advice I've always seen is to get in a ditch. I guess tying off to something (as was mentioned) couldn't hurt, but I think the main danger is being hit by debris