Dry heat vs humid heat

[Red Baron Farms]

I don’t agree.

100 def F with humidity over 82.5 humidity isn’t just uncomfortable it’s over the 95 deg wet bulb temperature which is lethal to healthy individuals.

At this temperature and humidity you don’t survive long enough to dehydrate and sweating becomes irrelevant as even wet skin can’t transport heat out of your body.
See the wiki quote from above

I'll buy that. 82.5 humidity is ridiculously high at 100 degrees. I have spent a lot of time in very hot very humid conditions, but I have never seen such a thing. Should that extreme happen, sure. You'll probably die before the other effects even have a chance to kick in. Especially when not acclimated. So I suppose I should have defined "high". Your way of being precise in definitions is much better.

 

[JoeTheJuggler]

It is my contention that while a humid 100°F is more miserable, (higher heat index), a dry 100°F is more dangerous.

And your evidence is. . . .

You don't need a fancy scientific study to prove this. Just go to an ecosystem with relatively many humid 100°F +/- days as compared to an ecosystem with relatively many dry 100°F +/- days. Look around. Which ecosystem has more life? Humidity is water and water = life in abundance.

The presence or absence of abundant plant life is not evidence that dry heat is more dangerous than humid heat at the same temperature.

 

[Red Baron Farms]

And your evidence is. . . .



The presence or absence of abundant plant life is not evidence that dry heat is more dangerous than humid heat at the same temperature.

I don't have proof per se. Just experience and the knowledge that dry heat dehydrates you significantly faster than humid heat, while causing further damages like nose bleeds, cracked and dry skin, eyes, throat, respiratory problems etc...

As far as plant and animal life as evidence? Maybe not direct evidence. Each species has evolved for different conditions. But the orders of magnitude more biomass is pretty good indirect evidence that dry heat is more stressful for life in general.

 

[wasapi]

I love humid heat. Overcast sky. Really. I function better, and feel better. I would do well in parts of South America. (Except for the bugs. )

When it is humid and hot, the air feels as if it has weight. Sultry. And, feeling as if I'm in a Tennessee Williams play.

No idea why. I wonder if there are many others who feel the same way.

 

[Travis]

With all due respect, Travis, that's the stupidest counter-argument I've read in a long time. That you happen to know of some people that are foolish enough that they forget to rehydrate themselves, says nothing about whether Dry Heat is better than Humid Heat. It is not the Heat's fault if some people forget to rehydrate. That does not affect the Heat's "score", but rather the person's.
As far as I understood, we were discussing which type of Heat is better, meaning which one is less miserable, easier to deal with. But now you seem to be moving the goalposts into trying to argue that Dry Heat is more dangerous, based on your personal experience that some people tend to forget to hydrate themselves, but I doubt you'll ever find me a serious statistical study that demonstrates that Dry Heat tends to make people forget to rehydrate themselves, and thus being more likely to kill people.

Who cares about heat score? The entire point of this thread was whether dry heat is dangerous and if people who live in a heat wave in a dry climate have the right to complain about it.

The only question I posed in the op was "Which is truly worse?"

And that can mean a multitude of things. I never asked what is worse 115F at 20% humidity vs 115F at 50% humidity. I only asked what people's opinions on the matter where.

But, hey, if we want to pretend that the dry regions of the country are soooooo lucky and never have people die there from the heat....well fine.

 

[Travis]

I suppose I could put forth the following challenge. On the 20th of August you have to walk 20 miles in the heat of the day to reach a station with drinking water. You can do this along US Route 190 in Louisiana or along California Route 190 through Death Valley.

Not knowing what the actual conditions will be like ahead of time which would you rather commit to?

 

[Puppycow]

I live in California. And each summer we will get a few bad heatwaves. While I'm sweltering under 115F (46C) conditions I'll suddenly have someone on the internet tell me that "at least it is a dry heat!" Which sort of makes me want to punch the wall. Which I won't do....of course because of the heat that I apparently shouldn't even notice.

So....dry heat vs humid heat.

DRY HEAT|HUMID HEAT
Easy to dehydrate|Easy to get heat stroke

Which is truly worse?

Come to Tokyo in August and see for yourself.

BTW, I just got back from a trip to CA and it was heaven. Of course, it wasn't anywhere near 115 F where I was, San Luis Obispo.

 

[Dymanic]

Who cares about heat score?

Well, NOAA, for instance -- since one of their functions is to decide when and whether to issue excessive heat warnings, and they have found the heat index to be a very reliable indicator.

The entire point of this thread was whether dry heat is dangerous and if people who live in a heat wave in a dry climate have the right to complain about it.

In the U.S., the First Amendment guarantees to all persons the right to complain about anything they choose. People who venture out in extreme heat without taking precautions such as insuring adequate hydration give up their free speech rights when they die. Is how it works.

The only question I posed in the op was "Which is truly worse?"

As posed, the question was a bust, right out of the gate. It's like asking whether the change of phase from liquid to vapor (liquid to solid, vice versa, etc) is "truly" more dependent upon temperature or pressure. The two factors are truly not separable.

I suppose I could put forth the following challenge. On the 20th of August you have to walk 20 miles in the heat of the day to reach a station with drinking water. You can do this along US Route 190 in Louisiana or along California Route 190 through Death Valley.

Not knowing what the actual conditions will be like ahead of time which would you rather commit to?

Considering that I wouldn't have a snowball's chance of completing a 20 mile trek in either of those places (or anywhere else, for that matter), Death Valley would seem more appropriate. But that's me. If I thought I did have a chance of surviving, I'd be inclined to go with the Louisiana route as long as the rules did not disallow walking somewhat off the roadway. I'd be looking to catch some shade at least part of the time by sticking close to the trees (a notably absent feature in Death Valley), the reason being that the difference in heat index between shade and full sun can be as much as 15 degrees. I suspect your rules would not allow that, however, and probably would not allow the use of parasols, straw hats, or any other forms of "cheating", either. Therefore, I'd go with Death Valley again. I'd be less miserable for that early leg of my death march during which I still had the ability to sweat, and once I became dehydrated, I would progress rapidly to hyperthermia, and thence to a relatively quick end. Probably even get some interesting hallucinations out of the bargain.

 

[lobosrul]

I suppose I could put forth the following challenge. On the 20th of August you have to walk 20 miles in the heat of the day to reach a station with drinking water. You can do this along US Route 190 in Louisiana or along California Route 190 through Death Valley.

Not knowing what the actual conditions will be like ahead of time which would you rather commit to?

Well lets see, Baton Rouge, LA has an average high of 92 on August 20th, with a very good shot at an afternoon rain shower. While Death Valley, CA has an average high of 114 with almost no chance of clouds or rain. You wouldn't really have any chance of going 20 miles with no water in either case, but in Louisiana, water might fall from the sky for you.

 

[Pulvinar]

Well lets see, Baton Rouge, LA has an average high of 92 on August 20th, with a very good shot at an afternoon rain shower. While Death Valley, CA has an average high of 114 with almost no chance of clouds or rain. You wouldn't really have any chance of going 20 miles with no water in either case, but in Louisiana, water might fall from the sky for you.

Or the water might come as part of a hurricane and kill you.

That's the problem with these comparisons-- it's often something other than the heat itself that does you in.

 

[Travis]

Well, would you rather live in Louisiana with its humidity or in Death Valley?

 

[Dymanic]

Well, would you rather live in Louisiana with its humidity or in Death Valley?

It is because I want to live that I'd choose not to reside in either place. Lived in Phoenix for six years, that was bad enough. Every summer I swore would be my last one in that town -- and that was back when I was in peak physical condition. Given my current physical limitations, it might as well be a moon base as far as I'm concerned. Regional power outage in July or August, and my life expectancy could be counted in hours.

 

[Jrrarglblarg]

Well, would you rather live in Louisiana with its humidity or in Death Valley?

When I posted the chart upthread I was hoping to move the "comparisons" portion of the conversation into the rational. Your question is irrational. Death Valley does not represent a normal environment but an extreme. Perhaps comparing Phoenix with New Orleans would be more rational as they represent two actual places where actual people actually live.

 

[wasapi]

Well, would you rather live in Louisiana with its humidity or in Death Valley?

Louisiana. No question about it. I've lived in both types of heat, and I know what I like.

 

[xtifr]

Look, no one is comparing a dry 100°F to a humid 100°F. I think it's clear to everyone which is more dangerous/miserable. I think what is being compared is similar heat index numbers. Which is more miserable or dangerous, 120° heat index with low humidity, or 120° with high humidity.

The problem with comparing the "heat index" is that it's somewhat disingenuous. High humidity won't make gallium melt any faster, and it won't make my pork chops cook any faster. It's a measure of how temperature+humidity affects humans, and as such, comparing how two different conditions with the same heat index affect humans should either A) give identical results, or B) show that the index is miscalibrated.

 

[luchog]

I don't have proof per se. Just experience and the knowledge that dry heat dehydrates you significantly faster than humid heat, while causing further damages like nose bleeds, cracked and dry skin, eyes, throat, respiratory problems etc...

As far as plant and animal life as evidence? Maybe not direct evidence. Each species has evolved for different conditions. But the orders of magnitude more biomass is pretty good indirect evidence that dry heat is more stressful for life in general.

No, it's not, it's merely evidence that moisture is necessary for life; and that plants and animals in high heat-index zones have adapted to those zones.

Dehydration is a very slow process, and even at the highest heat will take days to kill. It's also a red herring, since it's possible to dehydrate at the same rate regardless of the humidity level, since high humidity does not prevent sweating at the same rate as in dry air; it only prevents it from evaporating and cooling the body.

By contrast, heat stroke can kill in only a few hours. High humidity greatly reduces the body's ability to cool itself by sweating, leading to rapid overheating, heat exhaustion, and heat stroke.

All of the actual scientific evidence points to high humidity being a more more dangerous condition; which is why the military and just about anyone else working in a high-humidity environment depends on heat index rather than absolute temperature.

 

[luchog]

Who cares about heat score? The entire point of this thread was whether dry heat is dangerous and if people who live in a heat wave in a dry climate have the right to complain about it.

The only question I posed in the op was "Which is truly worse?"

And that can mean a multitude of things. I never asked what is worse 115F at 20% humidity vs 115F at 50% humidity. I only asked what people's opinions on the matter where.

But, hey, if we want to pretend that the dry regions of the country are soooooo lucky and never have people die there from the heat....well fine.

No one is saying that dry heat isn't dangerous; that is a disingenuous misreading.

The issue is that humid heat is more dangerous; because heat stroke kills much faster than dehydration. It's possible to get heat stroke in a dry climate, but it's much more likely in a humid one; which is why the Heat Index is a far more accurate and important measure of relative risk than absolute temperature.

 

[RussDill]

The issue is that humid heat is more dangerous; because heat stroke kills much faster than dehydration. It's possible to get heat stroke in a dry climate, but it's much more likely in a humid one; which is why the Heat Index is a far more accurate and important measure of relative risk than absolute temperature.

I don't think the idea here is that you'd die from dehydration in a dry heat, the death would still be from heat stroke, it'd just be that if you were low on fluids your body would not produce the amount of sweat required.

But as you say, yes, assuming the person stays hydrated the risk of heat stoke will be similar at similar heat index levels. Regardless of it being a dry heat or humid heat.

 

[GlennB]

No, it's not, it's merely evidence that moisture is necessary for life; and that plants and animals in high heat-index zones have adapted to those zones.

Yes. If you're a tree whose roots are actually in the water table (rain forest, mangrove, bayou) you don't give a damn about your transpiration rate. There's always ample water and you take advantage of that to multiply.

 

[Red Baron Farms]

No, it's not, it's merely evidence that moisture is necessary for life; and that plants and animals in high heat-index zones have adapted to those zones.

Dehydration is a very slow process, and even at the highest heat will take days to kill. It's also a red herring, since it's possible to dehydrate at the same rate regardless of the humidity level, since high humidity does not prevent sweating at the same rate as in dry air; it only prevents it from evaporating and cooling the body.

By contrast, heat stroke can kill in only a few hours. High humidity greatly reduces the body's ability to cool itself by sweating, leading to rapid overheating, heat exhaustion, and heat stroke.

All of the actual scientific evidence points to high humidity being a more more dangerous condition; which is why the military and just about anyone else working in a high-humidity environment depends on heat index rather than absolute temperature.

Well I disagree. In dry heat you loose a significant amount of water through respiration. Enough to make you dehydrated very quickly. It is not a slow process and will continue even after you stop sweating. This is much reduced in humid conditions.

You are right about humid heat reducing the body's ability to cool itself. I don't dispute that. That means you can get less work done before needing to rest. An important factor for the military or anyone needing to do physical labor outside in hot humid weather. But high heat low humidity will out right kill you from dehydration faster, much faster, unless you have access to a lot of water.